Maize Hybrid Looks Promising for Biofuel

From: TheBioenergySite News Desk (22 February 2012)

US – Scientists at the University of Illinois at Urbana-Champaign have identified a new contender in the bioenergy race: a temperate and tropical maize hybrid.

Their findings, published in GCB Bioenergy, show that the maize hybrid is potentially capable of producing ethanol from biomass (plant material used for biofuel production) at levels equal to or greater than ethanol produced from grain harvested from current commercial maize hybrids.

“Our maize hybrid, when grown using the same amount of fertiliser as commercial grain hybrids, produced 15-20 per cent more biomass than the commercial hybrids.” said Dr. Frederick Below, Professor of Crop Physiology at the University of Illinois.

The scientists selected plants with different genetic combinations created from a hybridization of temperate and tropical maize in order to incorporate beneficial characteristics of both tropical and temperate maize.

Accustomed to a tropical climate, the tropical parent plant experiences a much longer growing season in the Midwest than temperate varieties. Temperate maize minimises the negative traits of tropical maize such as disease and pest vulnerability while maximising positive traits such as drought tolerance.

Both parent plants combine to form a hybrid that grows larger and accumulates more stalk sugars than conventional grain hybrids, factors that increase ethanol output.

The scientists discovered that the hybrids are capable of producing as much ethanol per acre as maize currently grown for ethanol made from grain, but the hybrids require less input such as fertilizers like nitrogen and the ethanol could be produced from the vegetative plant material.

According to Dr. Below, “the temperate and tropical maize hybrid has the potential to produce the same amount of ethanol as commercial grain hybrids, but with lower nitrogen fertiliser requirements. This difference makes the hybrid more energy efficient and can result in a more sustainable environmental life cycle.”

Maize is often criticised by the scientific community as a poor choice for ethanol given the toll fertilisers can have on the environment. But as Dr. Below and his team have shown, the hybrid will significantly lessen the need for fertiliser application and provide an alternative, more environmentally sustainable feedstock for biofuel production.

While this new hybrid may be in its early stages, a wealth of information about maize has been long established, allowing for rapid improvements.


P240-M Plant to Bring In More Hybrid Corn Seeds

From: GMA News

A multinational company will build a P240-million plant to ramp up its production of hybrid corn seeds— a technology credited to boost crop yield but frowned upon by others for jeopardizing farmers’ welfare.

The Syngenta Philippines Inc. plant to be located in Binalonan, Pangasinan will sell hybrid seeds to local farmers and ship out a portion of its annual produce to neighboring countries in Asia, said Syngenta head for seeds Recher Ondap.

Hybrid seeds are the product of artificial breeding of two or more plants to come up with a variety with intended characteristics. “Syngenta ensures that farmers get seeds that are newly harvested, have excellent germination potential, and are well suited to local conditions,” Ondap said.

The Department of Agriculture has promoted the use of hybrid corn seeds, as well as other hybrid and genetically modified varieties, to increase crop yields.

An officer of a farmer’s welfare group, however, said that high-yield hybrid seeds come at the expense of farmers, who can only purchase the seeds from the companies that produce these.

Jean Lugasip, policy officer of the Southeast Asia Initiative for Community Empowerment (Searice), noted in an interview with GMANews.TV that farmers can use a batch of hybrid seeds, in effect, only once. Otherwise, undesirable traits of the hybrid crop — that do not manifest themselves in the first batch — may show up.

Farmers then will have to buy brand new batches of hybrid seeds every time they plant, Lugasip explained. She said the seed companies hold the patent for each of their hybrid seeds, which are priced higher than local varieties.

“Ang isyu namin sa hybrid seeds ay sino ang nag-o-own ng seeds na ito, at ang dependence ng farmers sa seed companies (Our issue with hybrid seeds concerns who own the seeds, and the dependence of farmers on seed companies),” Lugasip said.

Ondap meanwhile said the Syngenta processing plant would create jobs for about 150 people in Binalonan and nearby towns. He said the plant would also help improve the income of thousands of farmers in Pangasinan as they supply corn for processing.

Syngenta will buy their corn at a competitive fixed price. “Our new plant will contribute positively to the continued development of the local economy and surrounding community,” Ondap added.

Syngenta in the Philippines has been producing and distributing hybrid corn seeds since 2001.

New Miscanthus Hybrid Discovery in Japan could Open Doors for Biofuel Industry

From: e! Science News

In the minds of many, Miscanthus x giganteusis the forerunner in the race of viable feedstock options for lignocellulosic bioenergy production. But researchers believe “putting all their eggs in one basket” could be a big mistake. Scientists at the University of Illinois recently reported the first natural occurrence in several decades of Miscanthus hybrid plants in Japan. “If M. x giganteus is the only variety available, there are certainly risks involved such as diseases or pests causing widespread establishment problems or yield losses,” said Ryan Stewart, assistant professor of horticulture in the Department of Crop Sciences at the University of Illinois. “We are trying to find Miscanthus hybrids to increase our options. In doing so, it’s a way to hedge our bets.”

M. x giganteus is a sterile triploid (three sets of chromosomes) formed by a natural cross of M. sacchariflorus and M. sinensis. Because it’s sterile, it can only be propagated by vegetative division, which is somewhat more difficult than propagating by seed, Stewart said.

“Because it’s a sterile clone, it’s more or less a dead-end for plant breeders because it can’t be improved through plant breeding,” he said.

Stewart and his team investigated overlapping populations of tetraploid M. sacchariflorus and diploid M. sinensis in Japan in hopes of finding triploid hybrid plants that may be similar in productivity to M. x giganteus. However, finding this occurrence out in the wild is a rare event, he said.

“In Japan, even when two plant species are adjacent to one another, they may have very different flowering times, meaning the likelihood of finding a hybrid is very low,” Stewart added.

But Stewart knew that there were certain areas in Japan where M. sacchariflorus and M. sinensis sat side by side and had overlapping flowering times. So, with the help of his colleagues, Aya Nishiwaki of the University of Miyazaki and Toshihiko Yamada of Hokkaido University, they set out to search for these rare Miscanthus hybrids.

Last year, Nishiwaki was surprised to find a M. sacchariflorus plant, which was adjacent to some M. sinensis plants, with heavy seed set. M. sacchariflorus in Japan normally spreads vegetatively rather than through seed. Nishiwaki collected this seed, grew it out, and then used flow cytometry to determine the genome size of each of plants. Genome size can be used to detect hybridization events. In analyzing several seeds, their research revealed three triploid plants, which, based on some preliminary molecular analysis, were confirmed to be hybrids.

Researchers hope these new triploid plants will express phenotypic traits similar to that of the high-yielding M. x giganteus. But if they don’t, Stewart said they can still serve as sources of genetic variation that might express resistance to recently identified diseases and pests in the M. x giganteus.

M. x giganteus, the first known natural Miscanthus hybrid, was originally found in Japan and then made its way to Europe where it was initially used as an ornamental grass for estates or large gardens, Stewart said. It’s a highly productive grass that’s cold-hardy, notably for plants that use C4 photosynthesis, which are mostly found in the subtropics and tropics.

It is a popular candidate for bioenergy production because it can grow up to 15 feet tall, creating more biomass than other varieties of Miscanthus.

Stewart and his team have received funding to continue searching for hybrids and to build up a diverse collection of plants of several nativeMiscanthus species throughout Japan. This collection will serve as a resource for the Energy Biosciences Institute located in the Institute for Genomic Biology at the U of I. Future research will also address the phylogenetic relationship of these hybrids with other Miscanthus taxa, and also their agronomic potential relative to the commonly cultivated M. x giganteus.

Study shows, Modern Hybrid Corn Makes Better Use of Nitrogen

From: Purdue University News Service (30 April 2012)

WEST LAFAYETTE, Ind. – Today’s hybrid corn varieties more efficiently use nitrogen to create more grain, according to 72 years of public-sector research data reviewed by Purdue University researchers.

Tony Vyn, a professor of agronomy, and doctoral student Ignacio Ciampitti looked at nitrogen use studies for corn from two periods – 1940-1990 and 1991-2011. They wanted to see whether increased yields were due to better nitrogen efficiency or whether new plants were simply given additional nitrogen to produce more grain.

“Corn production often faces the criticism from society that yields are only going up because of an increased dependency on nitrogen,” said Vyn, whose findings were published in the early online version of the journal Field Crops Research. “Although modern hybrids take up more total nitrogen per acre during the growing season than they did before, the amount of grain produced per pound of nitrogen accumulated in corn plants is substantially greater than it was for corn hybrids of earlier decades. So, in that sense, the efficiency of nitrogen utilization has gradually improved.”

Vyn and Ciampitti’s analysis covered about 100 worldwide studies. Of those, 870 data points were taken from the earlier period through 1990, and 2,074 points were taken from studies after 1990, when transgenic hybrids started hitting the market. All studies involved analyses of total nitrogen uptake and grain yield by corn plants at maturity, usually in response to multiple nitrogen application rates.

Grain yields in these research studies averaged about 143 bushels of corn per acre over the last 21 years compared with an average of 115 bushels in the previous 50 years. Those studies showed that in the earlier period, one pound of nitrogen taken up by corn plants from soil and fertilizer sources  produced about 49 pounds of grain. In the more recent period, that same amount of nitrogen accumulated in the above-groundplant parts produced about 56 pounds of grain.

About 90 percent of the corn data points examined in Vyn’s study evaluated nitrogen rates between zero and 250 pounds per acre. Over both periods, the average rate of nitrogen fertilizer distributed in experimental fields was nearly the same – 124 pounds per acre in the earlier period vs. 123 pounds in the later period.

Vyn said genetic improvements have led to corn plants that require less space around them, allowing growers to squeeze more plants into an acre. Research fields from the modern era averaged about 28,900 plants per acre – about the average final plant populations in Indiana cornfields in 2011 – compared with 22,800 plants per acre from 1940-1990.

“The maximum individual plant nitrogen uptake stayed exactly the same despite the average gain of 6,000 more plants per acre,” Vyn said. “The modern plants are just more efficient at taking nitrogen up and utilizing it than they were before.”

Vyn and Ciampitti are working toward methods to increase grain yields further by investigating the contribution of nitrogen to plant biomass and yield formation processes in high-yielding hybrids under a wide range of nitrogen inputs and production stress factors. Knowing that modern hybrids are sustaining a reasonable quantity of nitrogen uptake even under progressively higher plant densities is a good start, Ciampitti said.

“We are getting clues on how plants have already improved nitrogen use efficiency, and we will use that to push for further increases,” Ciampitti said. “We finally feel like we’re shedding some light on what traits plant breeders should select for to increase nitrogen efficiency even more.”

Vyn and Ciampitti plan to further investigate how water use efficiency and nitrogen use efficiency are tied together, as well as how plants can achieve more tolerance to environmental stresses.

Dow AgroSciences, PotashCorp and the U.S. Department of Agriculture National Institute of Food and Agriculture funded their work.

Crozet Farm to Plant Chestnut Hybrids in Restoration Effort

By: Aaron Richardson (6 April 2012)

Chestnut planting

Above: A large-scale planting of chestnut seedlings is seen at a farm in Washington County, Va.

At the turn of the 20th century, it was nearly impossible to go outside in Central Virginia and not see a towering American chestnut tree. At that time, American chestnuts accounted for nearly one in four of the trees in the Blue Ridge Mountains.

Then, in barely half a century, the American chestnut was gone.

The hardy trees, prized for their rot-resistant hardwood lumber and plentiful nuts, had been killed by a fungal blight carried by the Chinese chestnut.

The American trees had no resistance to the fast-moving blight, which spread at a rate of 50 miles a year across the tree’s Maine-to-Georgia range.

Beginning today, Fried Farm in Crozet will join an effort to introduce a blight-resistant hybrid of the American chestnut and the Chinese chestnut to Central Virginia.

Owner Barbara Fried said the possibility of reviving the once-plentiful trees and a love of forests drew her to the project.

“It’s a magnificent tree and it’s as American as they come,” Fried said. “It would be exciting if the one that were the best hybrid were on our property.”

Fried said today’s planting won’t be the first time she has tried to grow American chestnuts.

“My husband and I always were interested in forests and trees, and earlier I had planted some trees and put wire around them and they just didn’t survive,” she said.

Volunteers with the American Chestnut Foundation will plant three acres of the farm with 169 germinated seeds of American-Chinese chestnut hybrids. The trees are the result of an ACF breeding program that crosses the blight-resistant Chinese chestnut with the vulnerable American tree.

The foundation wants to breed trees that contain as high a proportion of American chestnut genes as possible, but contain enough of the Chinese tree’s DNA to combat the blight.

According to Cathy Mayes, chairwoman of the ACF’s Virginia chapter, the Chinese chestnut was introduced to the United States by European immigrants who wanted a tree that would grow well in orchards and be easy to gather nuts from.

American chestnuts, she said, fare much better in forests, and, because of their size, are extremely difficult to harvest from.

Before the blight, Mayes said, the tree was a vital part of the economy and environment throughout its range. Chestnut trees fed and housed small mammals and birds, which became prey for larger animals. People harvested the trees for lumber, which was strong and easy to saw.

“At the time that the blight came through, chestnuts were as common as grass,” Mayes said. “So when the blight came through it was just devastating to the economy, the ecology and the beauty of the state.”

The fungus, Mayes said, took about 100 years to gain a foothold in the American chestnut population. After that, it spread quickly.

“Once it was diagnosed as a fungus, it wiped out about 4 billion trees in about 50 years,” she said. “Whole hillsides looked like toothpicks.”

The blight, which entered the tree through a wound in the bark, generally killed infected trees within a year of infection.

The trees going in at Fried Farm are fourth-generation hybrids, which contain 93 percent American genes. Genes from the Chinese trees give the hybrids a moderate resistance to the blight. When these trees reach sexual maturity, in about 10 years, they will be bred together in the hopes of finding a small number of strongly blight-resistant trees.

Virginia ACF President John Scrivani, who spent 20 years with the Virginia Department of Forestry, said the process of breeding blight-resistant trees will not be a quick or easy process.

“Our restoration plan is very long-term,” Scrivani said. “It will take hundreds of years to get the population re-established in the forest anything like what it was 100 years ago.”

Creating the hybrids that will go on Fried Farm takes breeding a Chinese chestnut and an American chestnut, then breeding the hybrid offspring with full American chestnuts, a process called backcrossing.

The trees planted at Fried will be bred together, which should produce one in 64 offspring that contain the strong resistance gene. When a strong population of those trees exists, they will be bred to reliably produce strongly blight-resistant trees.

“You can expect that if you perfectly picked resistant trees, that they will all be resistant,” Scrivani said. “There will be errors, but we’re pretty confident we can generate a population that will be strongly resistant.”

Similar orchards of blight-resistant trees already exist in Washington County, but planting those trees in this part of the state would limit genetic diversity.

To keep the population diverse, Scrivani said, trees must be bred in the general area they will repopulate. That allows the trees to adapt to the soils and climate of different parts of their range, which gives them a much better chance of survival.

“The [trees] that are being planted [today] are Central Virginia trees,” Scrivani said. “In 10 to 15 years, we’ll be able to plant these out to create that [resistant] generation for Central Virginia.”

While the native American chestnut population was devastated by the blight, some trees still get big enough to flower, which means they can breed. Their genes are harvested to help create a blight-resistant population of trees native to this area.

“We do find the rare surviving tree that has grown large enough to flower, and that is how we get local genetics into the population,” Scrivani said.

Planting the trees is an all-volunteer activity. The planting kicks off at 9:30 this morning, and Fried said she has plenty of extra trowels for those who want to help.

“The chestnut foundation is comprised of a lot of good volunteers,” Fried said. “They couldn’t get by without the help of their volunteers.”

Two Species Fused to Give Rise to Plant Pest

3 July 2012

A fungal species native to Iran which attacks grasses is the result of natural hybridisation that occurred just a few hundred years ago.

Zymoseptoria tritici is often a headache for European farmers. This ascomycete originating from the Middle East attacks the leaves of wheat plants triggering “speckled leaf blotch”, which can cut crop yields by up to 50 percent. Scientists from the Max Planck Institute for Terrestrial Microbiology in Marburg and Aarhus University in Denmark have now taken a close look at the genome of a close relative, Zymoseptoria pseudotritici and have made a surprising discovery. The fungus which, unlike its more globally active cousin, preferentially attacks grasses in Iran, clearly arose just a few hundred years ago from the fusion of two unknown parent species. The researchers’ results make it clear that entirely new and successful pest species can arise extremely rapidly by natural hybridisation.

© Janine Haueisen

Above: Two isolates of the fungus species Zymoseptoria pseudotritici, growing on water agar. The fungus originated from the hybridisation of two parents from different species

If two different species breed successfully, the descendants are known as hybrids. While animal hybridisation in the wild tends to be a short-lived exception, primarily because the offspring are frequently less fit or even infertile, in plants and fungi speciation by crossing is an “everyday” evolutionary event. However, what happens at the gene level was previously unknown: in naturally occurring hybrid species, the initial mixing of the genomes usually took place so long ago that almost no traces remain in the genetic material.

Eva Holtgrewe Stukenbrock’s team from the Max Planck Institute for Terrestrial Microbiology has now, for the first time, investigated the genome of a very recent hybrid population, in which, in evolutionary terms, hybridisation has only just occurred. The researchers have sequenced and aligned the genomes of five individuals of the fungal speciesZymoseptoria pseudotritici which originates from Iran. “This revealed an unusual pattern of diversity”, says Eva Stukenbrock. “We found numerous long regions that were identical in all the individuals. These were, however, regularly interspersed with highly variable segments.”

These variable segments could always be assigned to two different “haplogroups”, an individual comprising either one type or the other. The researchers soon worked out what had happened: these are the traces of a natural hybridisation event in the past. The genetic material of both “parent species” has clearly been retained within the population in the variable gene segments, while the identical regions in each case retain only the genetic information from one of the parents.

But that’s not quite the whole story. By investigating the topology of the identical and variable segments, the degree of similarity and further characteristics of the genetic information, the scientists were able to reconstruct the entire evolutionary history of this recent fungal species. “The entire present day population originates from two individual parents from different species which crossed only once. Backcrossing between the parent species and the hybrids can certainly be ruled out”, explains Eva Stukenbrock. “We can also state that hybridisation occurred around 380 generations ago. Given a typical rate of reproduction of at least once to around three times per year, speciation therefore occurred around 200 years ago.”

The identity of the two original parents remains unclear, however. “We could not identify any matching species from our Iranian sample collection. This may either be purely and simply because our samples do not reflect the entire range of pest diversity, or because the hybrid descendants have driven out the parent species”, she says. And this would not seem all that unlikely, as it is precisely in plants and fungi that new hybrids often have new characteristics that enable colonisation of other habitats or even offer competitive advantages over pre-established species.

This study by the Marburg-based researchers shows that new fungi which can also be of significance to agriculture can develop and successfully propagate extremely rapidly. “World trade in agricultural products promotes the rapid evolution of plant pests”, says Eva Stukenbrock, “and this happens very simply by local fungal species, for example living on wheat, being unintentionally brought into contact with introduced species, which can then cross and form new species.”

New Flowering Plant in Scotland

From: sci-news (11 July 2012)

Biologist Dr Mario Vallejo-Marín from the University of Stirling has found a new species of monkey flower, created by the union of two foreign plant species, on the bank of a stream in Scotland.

Species: Mimulus peregrinus from Leadhills, South Lanarkshire (M.Vallejo-Marín)

Genetic changes in this attractive yellow-flowered hybrid have allowed it to overcome infertility and made it a rare example of a brand new species that has originated in the wild in the last 150 years.

Thousands of wild species and some crops are thought to have originated in this way, yet only a handful of examples exist where this type of species formation has occurred in recent history.

The ancestors of the new plant were brought from the Americas as botanical curiosities in the 1800s and were quickly adopted by Victorian gardeners. Soon after their arrival, they escaped the confines of British gardens and can now be found growing in the wild, along the banks of rivers and streams. Reproduction between these species produces hybrids that are now widespread in Britain. Yet, genetic differences between the two parents mean that the hybrids are infertile and cannot go beyond the first generation.

The biologist has documented the first examples of hybrid monkey flowers that have overcome these genetic barriers and show fully restored fertility. This fertile hybrid derived from ‘immigrant’ parents represents a new species, native to Scotland.

Dr Vallejo-Marin has chosen to name this species Mimulus peregrinus, which translates as ‘the wanderer’. The species is described in a paper in the journal PhytoKeys.

“The two American monkey flowers are unable to produce fertile hybrids due to differences in the amount of DNA present in each species, the equivalent of getting a sterile mule from crossing a horse and a donkey”, Dr Vallejo-Marin. “However, in rare cases, duplication of the entire hybrid DNA, known as polyploidization, can balance the amount of DNA and restore fertility. Our studies suggest that this is what has happened here.”

The discovery will help scientists to understand how new species form. It is thought that many existing plant species including crops such as wheat, cotton and tobacco may have originated in a similar way, but finding examples of this process in action is rare.

“This is an exciting opportunity to study evolution as it happens,” Dr Vallejo Marin explained. “We do not yet know how common the new species is or how well it will fare, so the next step will be to find out its distribution and whether its ecological characteristics, allow it to colonize environments that cannot be currently exploited by its parents.”

A New Source of Maize Hybrid Vigor

From: ScienceDaily (28 June 2012)

Steve Moose, an associate professor of maize functional genomics at the University of Illinois and his graduate student Wes Barber think they may have discovered a new source of heterosis, or hybrid vigor, in maize. They have been looking at small RNAs (sRNAs), a class of double-stranded RNA molecules that are 20 to 25 nucleotides in length.

“Hybrid vigor” refers to the increased vigor or general health, resistance to disease, and other superior qualities arising from the crossbreeding of genetically different plants. “We’ve always known that there’s a genetic basis for this heterosis,” said Moose. “Charles Darwin noticed it and commented that corn was particularly dramatic.”

Scientists have been debating the sources of hybrid vigor since the early 1900s when Mendel’s laws were rediscovered. Many of them disagreed with the model that prevailed from the 1920s to the 1950s, which linked heterosis to a single gene or to the interaction of several genes. “It seemed that the whole genome was involved,” said Moose.

The discovery of DNA in 1953 eventually caused a paradigm shift in the way people looked at hybrid vigor but, Moose said, there was no unifying theory. Even as new genetic technologies were developed, the genes did not seem to explain everything.

“We thought that maybe it’s the rest of the genome, the remaining 85 percent of the corn genome, that’s important,” said Moose.

sRNAs were originally found in 1998 in roundworms. Researchers studying virus resistance in plants then began to notice them and observed that the way that they function is very different from the functioningof protein-coding genes.

“Every time we have a breakthrough in our knowledge of genetics, people have looked to see if that breakthrough brings any insight into the mystery of the hybrid vigor,” said Moose. “That’s what we’ve done with the small RNAs.”

“When you think about what small RNAs do, they participate in regulating growth and they tell other genes what to do,” he continued. “So they have the two properties that we know fit what has been described (about heterosis) even though we do not have an explanation. We would argue that, while they are part of the explanation, they may not be the whole explanation.”

Moose and Barber sampled small RNAs from the seedling shoot and the developing ear of maize hybrids, two tissues that grow rapidly and program growth, to investigate how the small RNA profiles of these hybrids differed from those of their parents. In collaboration with associate professor of crop sciences Matt Hudson, they analyzed what they described as a “deluge” of data.

“There were 50 million data points, but we whittled it down to the most important ones,” said Barber.

They found that differences are due mainly to hybrids inheriting distinct small interfering RNAs (siRNAs), a subset of sRNAs, from each parent. The siRNAs interfere with gene expression. They also found that hybridization does not create new siRNAs, but hybrids have a more complex siRNA population than their parents because they inherit distinct siRNAs from both parents.

Moreover, the differences in parental siRNAs originated primarily from repeats, which are the result of retrotransposon activity. Retrotransposons are elements that move around and amplify themselves within a genome.

“This is a new source of genetic diversity that people had overlooked,” said Barber.

“We are not saying that genes are not important,” said Moose. “”But probably the way corn properties are altered in the hybrid situation is mediated by the small RNAs in addition to the genes.”

Moose and Barber hope that their work might provide more insight into how to decide which inbred maize lines to cross. “We don’t want to alter how the plant grows, but if we can tweak it to do whatever it already does either faster or more, that could be an advantage,” said Moose.

UF Research on Newly Formed Plants could lead to Improved Crop Fertility

From: University of Florida (6 January 2012)

GAINESVILLE, Fla. — A new University of Florida study shows genomes of a recently formed plant species to be highly unstable, a phenomenon that may have far-reaching evolutionary consequences.

Published online this week in the Proceedings of the National Academy of Sciences, the study is the first to document chromosomal variation in natural populations of a recently formed plant species following whole genome doubling, or polyploidy. Because many agricultural crops are young polyploids, the data may be used to develop plants with higher fertility and yields. Polyploid crops include wheat, corn, coffee, apples, broccoli and some rice species.

“It could be occurring in other polyploids, but this sort of methodology just hasn’t been applied to many plant species,” said study co-author Pam Soltis, distinguished professor and curator of molecular systematics and evolutionary genetics at the Florida Museum of Natural History on the UF campus. “So it may be that lots of polyploids – including our crops – may not be perfect additive combinations of the two parents, but instead have more chromosomes from one parent or the other.”

Researchers analyzed about 70 Tragopogon miscellus plants, a species in the daisy family that originated in the northwestern U.S. about 80 years ago. The new species formed naturally when two plants introduced from Europe mated to produce a hybrid offspring, and hybridization was followed by polyploidy.

Using a technique called “chromosome painting” to observe the plants’ DNA, UF postdoctoral researcher and lead author Michael Chester discovered that while whole genome doubling initially results in a new species containing 12 chromosomes from each parent, numbers subsequently vary among many plants.

The paints are made by attaching different dyes to DNA of the two parent species. Once the dye is applied, there is a match between the DNA of the paint and of the chromosome. Under a microscope, the chromosomes appear in one color or the other (red vs. green) depending on the parent from which they originated. Sometimes chromosomes are a patchwork of both colors because DNA from the two parents has been swapped as a result of chromosomal rearrangements.

“One of the things that makes this so amazing is that where we expected to see 12 chromosomes from each parent (the polyploid has 24 chromosomes), it turns out there aren’t 12 and 12, there are 11 from one parent and 13 from the other, or 10 and 14,” Soltis said. “We’re hoping through some ongoing studies to be able to link these results with the occurrence of another interesting phenomenon – the loss of genes – and also see what effect these changes have on the way the plants grow and perform.”

The polyploid’s two parent species, Tragopogon dubius and Tragopogon pratensis, were introduced to the U.S. in the 1920s. Because its flower only blooms for a few hours in the morning, Tragopogon miscellus is often referred to as “John-go-to-bed-at-noon,” and its common name is goatsbeard. It looks like a daisy except for being yellow in color.

“People have looked at these chromosomes before, but until you could apply these beautiful painting techniques, you couldn’t tell which parent they each came from,” Soltis said.

Of the six populations examined from Washington and Idaho, 69 percent of the plants showed a deviation from the expected 12 and 12 chromosome pattern.

“In order for most plants to be able to interbreed successfully, their chromosomes need to match up,” Chester said. “That doesn’t necessarily happen when you don’t have equal numbers, so there may be some chromosomal barriers to fertility that develop as a result of this sort of chromosomal variation. This mechanism may also explain low fertility in other plants, such as crops. This is something we are looking into with Tragopogon.”

The two-year study was funded by the National Science Foundation. Other co-authors include Doug Soltis, a distinguished professor in UF’s biology department, UF undergraduate biology student Joseph Gallagher and Ana Veruska Cruz da Silva of Embrapa Tabuleiros Costeiros in Brazil and the Florida Museum.

“Among all of the processes that generate biological diversity in the plant kingdom, genome doubling, or polyploidy, is among the most prevalent and important,” said Jonathan Wendel, professor and chairman of the department of ecology, evolution, and organismal biology at Iowa State University, in an email. “This is an area that is receiving international focus and research attention, but the system Pam and Doug Soltis are working on is unique.”

Distribution of Spontaneous Plant Hybrids

By: N C Ellstrand, R Whitkus and L H Rieseberg

Natural hybridization is a relatively common feature of vascular plant species and has been demonstrated to have played an important role in their evolution. Nonetheless, it is not clear whether spontaneous hybridization occurs as a general feature of all plant families and genera or whether certain groups are especially prone to spontaneous hybridization. Therefore, we inspected five modern biosystematic floras to survey the frequency and taxonomic distribution of spontaneous hybrids. We found spontaneous hybridization to be nonrandomly distributed among taxa, concentrated in certain families and certain genera, often at a frequency out of proportion to the size of the family or genus. Most of these groups were primarily outcrossing perennials with reproductive modes that stabilized hybridity such as agamospermy, vegetative spread, or permanent odd polyploidy. These data suggest that certain phylogenetic groups are biologically predisposed for the formation and maintenance of hybrids.