A large-scale study of over 500 rye plants reveals that nutrient deficiency reduces genetic recombination during meiosis. Conducted at Martin Luther University’s “Eternal Rye Cultivation” site, researchers found recombination is governed by many small genetic regions, not one master switch. These insights could accelerate breeding of resilient crops adapted to environmental stress.
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The researchers explored the genetic foundations and environmental flexibility of meiotic recombination in a large rye population. More than 500 rye plants were studied — some grown under standard conditions and others subjected to nutrient deficiency. Plant material was sourced from the Federal Ex Situ Genebank at IPK and from commercially available population varieties. All plants were cultivated at Martin Luther University Halle-Wittenberg’s long-running “Eternal Rye Cultivation” experiment.
Established in 1878 by Julius Kühn, this experiment remains active today. It compares different nutrient and humus replacement systems in a continuous series of trials, ranging from farmyard manure and complete mineral fertilisation to plots left entirely unfertilised.
“This area was particularly well suited to the study because the nutrient deficiency had built up over a very long period, making it very stable,” explained Dr. Steven Dreissig, head of the Plant Reproductive Genetics independent research group.
The researchers collected pollen and sequenced the nuclei of more than 3,000 sperm cells from 584 rye plants. Their goal was to quantify crossover events between parental chromosomes and pinpoint their precise locations. For the first time, this process was examined directly within pollen — the very site where it occurs — and on such a large scale, according to a press release.
“We were able to show that plant genes mix significantly less when there is a nutrient deficiency than when nutrients are supplied in adequate amounts,” says Christina Wäsch, the study’s first author. “You can think of it like playing cards: if the cards are only shuffled half-heartedly, fewer new combinations are created.” However, that’s not all. The research team also discovered differences between plant types. While the modern cultivar remained relatively stable during the study, old varieties and wild forms were susceptible to stress, explains Christina Wäsch. “This shows that genetic diversity plays a major role in how plants cope with environmental changes.”
The research team also investigated the genetic basis of recombination. “In our study, we demonstrated that the recombination rate is not controlled by a single master switch, but rather by numerous small genetic regions acting in concert,” explains Dr. Steven Dreissig. More than 40 alleles and two candidate genes are now known. “We now know the areas on the chromosome where these numerous genetic switches are located, but we often do not yet know all the decisive genes.”
“Nevertheless, our current study makes an important contribution to our understanding of the genetic architecture and environmental plasticity of meiotic recombination”, says Dr. Dreissig. “Unlike previous studies, which only examined individual or a few genotypes, we analysed the genetic effects in a large, genetically diverse population.” The IPK researcher believes identifying the genes that control recombination under stress could be a valuable breeding tool. “The targeted control of recombination under stress will help to accelerate the development of new, improved crops that are more resistant to adverse environmental conditions.”
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