Genetic Divergence Analysis Between Common Wheat And Wild Wheat

People discovered the taste and efficacy of various foods and medicines in the process of finding food.They realized that many foods can be used medicinally,and many medicines can also be eaten.This is "the homology of medicine and food".Research shows that the role of drugs in human health is only 8%,while a reasonable diet can play a role of 13%.Common wheat,Triticum aestivum,is one of the most important staple foods for human daily life.Its richness in protein and minerals is very important for people's daily nutritional needs,and it helps to improve and strengthen the body.After the out of Africa,people have modified unpalatable wild wheat into the most commonly used cultivated wheat.Many traits such as seed size,taste,and secondary metabolite contents have changed,but the molecular mechanisms behind the convert of these traits and the corresponding genetic alterations of wheat genome are still unclear.Therefore,it's very important to study the changes of genetic materials and gene expression patterns from wildness to cultivar.The common wheat genome(AABBDD,2n=42)consists of three closely related sub-genomes that are highly repetitive in sequence.They originated from three diploid wheat weeds that have diverged about six or seven million years ago,and hundreds of thousand years ago,Triticum Urartu,the ancestor of A genome and wild ancestor of B genome hybridized naturally and images of wheat and doubled to form a tetraploid wild wheat(T.turgidum;AABB,2n=28),and they have been bred and improved by humans for nearly 10,000 years.A wide variety of wheat varieties are emerging that are critical to food security and human health.To investigate the genetic diversity and domestication of worldwide cultivars,we analyzed genomic data of 93 accessions,of which 75 accessions are sequenced by ourselves,including wild relatives,durum wheats,common wheat landraces and modern varieties.We constructed the whole-genome genetic variation atlas.On this basis,we found that the genetic diversity of Common wheat on A and B genome is only a half of wild emmer wheat.While genetic diversity of D genome is far below that of Ae.tauschii,the ancestry of D genome due to theextremely severe bottleneck.Population genetic analysis suggested that Common landraces could be divided into two mainly clusters: European cluster,landrace-I and Asian cluster,landrace-II,and modern varieties have a uniform genetic background for all three sub-genomes.On A genome,varieties have closer genetic distance with landrace-II,while they are closer with landrace-II on B genome.We found that B sub-genome has much more deletions than A(nearly twice than A in deletion length)and D sub-genomes,implying that B genome has gone through more gene loss.Compared with B genome,we detected stronger artificial selection both in domestication and improvement process.In all,370 and 168 selection sweeps were detected on domestication and improvement process,respectively.In particular,we have found a clear selection signal on key genes in the isoflavone synthesis pathway.And in the two tissues of roots and leaves,the expression levels of phenylalanine ammonia-lyase and chalcone isomerase genes in domesticated wheat were significantly lower than those in wild Ae.tauschii.Our research revealed that the genetic changes that occurred during the domestication and improvement of wheat from wild to modern cultivars and will provide technical support for modern wheat molecular assisted breeding.