The Genes Mapping For Spike-related Traits In Multi-spikelet Wheat Germplasm 10-A

Wheat is one of the most important crops in the world.Wheat spike-related traits have an important contribution to final wheat yield.Spikelet number per spike?SN?,thousand-kernel weight?TKW?and awn length?AL?are important components of spike-related traits in wheat.In this study,the RIL populations of 10-A/BE89 F₇ and10-A/B39 F₆ were constructed using wheat multi-spikelet germplasm 10-A.The candidate regions controlling the SN and AL in the 10-A/BE89 population,and TKW and AL in the 10-A/B39 population,were mapping using the wheat 660K SNP chip combined bulked segregant analysis?BSA?method.The candidate genes for target traits were filtered by qRT-PCR.Those lay the foundation for fine mapping,genes cloning and molecular-assisted breeding of the related traits.The main findings of this study are as follows:?1?The traits of the parents and the populations were investigated.The result showed that 10-A performed significant differences in SN,TKW and AL compared with BE89 and B39.In 10-A/BE89 population,the average value of SN and AL were22.35 and 3.63 cm,and the coefficients of variation?CV?of them were 10.55%and63.67%,respectively.In 10-A/B39 population,the average value of TKW and AL were 47.3g and 3.78 cm,and the CVs of them were 21.47%and 72.81%,respectively.The 30 lines with the maximum value and the 30 minimum lines with minimum value for each trait were selected to construct the bulked pools.The high-throughput scanning was done between three parents and eight bulk pools using the wheat 660K SNP chip.In 10-A/BE89 population,a total of 5070 polymorphic SNPs with chromosomal information were detected.The largest number of polymorphic SNPs was 518 in 4A chromosome,and the smallest one was 20 in 4D chromosome.In10-A/B39 population,a total of 3923 polymorphic SNPs corresponding chromosomal information were observed.The largest number of the polymorphic SNPs was 865 in3B chromosome,and the least one was 16 in 4D chromosome.?2?A total of 177 polymorphic SNPs were detected between bulk poos for SN.The p-SNP ratio?the ratio of difference SNP between the pools and that betwwen the parents on each chromosome?showed the largest value,as 22.75%,on the 6B.The peak of the difference site ratio?c-SNP ratio?appeared near 170Mb,and further the160-180Mb interval of the 6B was named as the candidate interval C1.This region including three differential SNPs.A total of 109 genes were retrieved in C1 region,only three candidate genes were associated with the l SNPs.?3?A total of 197 polymorphic SNPs were detected between bulk pools for TKW.The p-SNP ratio was the largest as 35.9%in 5A,and the peak of the c-SNP ratio appeared near 80Mb and the 70-90Mb intervals was selected as the candidate interval C3,which includes 16 differential SNPs.And it was speculated to control the new interval of TKW.A total of 106 genes was detected in the C3 region,and 20 candidate genes were related to of the 11 differential SNPs.?4?The p-SNP ratio of AL peaked on 7B?10.07%?and 3B?29.83%?chromosomes in the two populations.The c-SNP ratio was the largest at 760Mb on the 7B,and taking the 750-770Mb intervals as the candidate region C2,which contained one differential SNP.A total of nine candidate genes associated with the locus.On the 3B,the c-NP ratio peaked at positions 270Mb and 310Mb.The segments 260-280Mb and 300Mb-310Mb were selected as candidate intervals C4 and C5.A total of 43 and 21 genes were retrieved in the candidate interval C4 and C5,respectively.Only seven candidate genes were associated with four different SNPs in the interval C4,and only three candidate genes were located in the extension of two differential SNPs in the interval C5.Intervals C2,C4 and C5 might be new regions for AL by comparison.?5?A total of 10 candidate genes were screened between parents from 42candidate genes by RT-PCR.The result showed that the number of candidate genes for SN,TKW and AL were 1,4 and 5,respectively.The results further verified by qRT-PCR showed that the candidate genes TaAPRT-5A and TaUFO-5A for TKW,and TaAL7B.2 for AL,showed significant expressing differences between parents.The homologous genes of TaAPRT-5A encodes adenine phosphoribosyltransferase?APRT?and the homologous genes of TaUFO-5A encodes unusual floral organs?UFO?protein.The candidate gene TaAL7B.2 had no annotated information.There were no significant differences among the other 7 candidate genes between the parents.