ABSTRACT
Bread wheat expanded its habitat from a core area of the Fertile Crescent to global environments within ~10,000 years. The genetic mechanisms of this remarkable evolutionary success are not well understood. By whole-genome sequencing of populations from 25 subspecies within the genera Triticum and Aegilops, we identified composite introgression from wild populations contributing to a substantial portion (4-32%) of the bread wheat genome, which increased the genetic diversity of bread wheat and allowed its divergent adaptation. Meanwhile, convergent adaptation to human selection showed 2- to 16-fold enrichment relative to random expectation-a certain set of genes were repeatedly selected in Triticum species despite their drastic differences in ploidy levels and growing zones, indicating the important role of evolutionary constraints in shaping the adaptive landscape of bread wheat. These results showed the genetic necessities of wheat as a global crop and provided new perspectives on transferring adaptive success across species for crop improvement.
Subject(s)
Acclimatization/genetics , Genome, Plant/genetics , Triticum/genetics , Biological Evolution , Bread/microbiology , Crops, Agricultural/genetics , Crops, Agricultural/physiology , Evolution, Molecular , Genetic Variation/genetics , Phylogeny , Whole Genome SequencingABSTRACT
In a field study, the quantitative changes of bacterial, actinomycetic and fungal populations on the leaf surface of transgenic Bt cotton (GK-12) and non-transgenic Bt cotton (Simian No. 3) were monitored at seedling, squaring, flowering and boll-opening stages, respectively, and the diversity of bacterial physiological groups was analyzed at flowering and boll-opening stages. The results showed that there was a positive correlation between the quantity of culturable microorganisms and the development of cotton. The total number of bacteria, fungi and actinomyces began to rise at seedling stage, reached its peak at flowering stage, and decreased markedly at boll-opening stage. The Simpson index, Shannon-Wiener index, and evenness index of bacterial physiological groups were higher at flowering stage, but lower at boll-opening stage on GK-12 than on Simian No. 3.
