Study On Genetic Diversity Of FISH Loci Of The Common Wheat From Different Geographic Origin

Common wheat(Triticum aestivum L.,2n = 6x = 42,AABBDD)is one of the most important food crops in the world.It is widely distributed spanning from 67 degree north latitude to the 45 degree south latitude,which is mainly concentrated in the 30-45 degree north latitude.Nowadays,the genetic basis of common wheat is narrow,the genetic diversity is decreasing,and the adaptability is poor.As a result,the improvement of wheat yield,resistance,and quality is constrained.Importantly,in recent years the supply of wheat is decreasing,whereas the demand is increasing.Therefore,improving the yield,quality,and resistance of cultivated wheat and increasing the genetic diversity of wheat are of great significance in wheat genetic and breeding researches.It is of great significance to introduce foreign wheat germplasms,and evaluate their genetic diversity and select excellent materials for enriching the genetic basis of wheat.The present study aimed at characterizing the genetic diversity of the 149 common wheat accessions originated from13 countries spanning from 30 to 45 degree north latitude by Fluorescent in situ hybridization(FISH)and analyzing genetic polymorphisms of the tested wheat resources taking advantage of probes Oligo-pSc119.2-1and Oligo-pTa535-1.The main results are as follows:1)The FISH signals of all materials were highly abundant and polymorphic.The levels of polymorphisms of FISH loci in genome A,B,and D were: B ? A ? D.The abundance of polymorphisms in A and D genome were the highest in materials coming from southern European,followed by that of western Asia,however the B genome was the opposite.The polymorphisms of A,B,and D genomes of materials from east Asian were the lowest,especially in China.2)Analysis of genetic diversity of A genome showed that 5A is the highest,while 6A and 7A is the lowest.In B genome,7B had the highest genetic diversity,while 1B,2B,and3 B showed the lowest diversity.The genetic diversity of D genome is ranked by 1D = 3D >2D = 4D > 5D = 6D = 7D.3)The four translocation types patterns,including 3A/7D,4A/3B,4B/6B,and 6B/3D,were found,which enriched the variation of FISH loci.Translocation chromosomes weremainly found in the wheat accessions from Europe and West Asia,with the B genome showing the highest translocation frequency.4)The average genetic similarity coefficient of FISH loci was 0.867,indicating a low genetic diversity expressed in all materials.All wheat accessions were divided into three subclades: the cladeI is composed of most of southern Europe(Spain,Portugal,Italy)originated materials and a few genotypes originating from other countries;CladeII comprised most of the materials from west Asia(Armenia,Afghanistan)and South Korea;CladeIII is comprised of most of the materials from Turkey,Greece,Bulgaria,China,Japan,and a few of material from other countries.