| Wheat(Triticum aestivum L.)is one of the most important staple crops in the world.The productivity and quality is very important for agricultural sustainable development and the food supply in China.Nitrogen(N)is one of the three most important nutrients for the growth and yield improvement of wheat.A lot of N fertilizers are supplied every year to grain high wheat productivity.But N efficiency of wheat is relative low,which increased crop production costs,exhausted non-renewable N resources,and caused a series of environmental problems.In this study,we conduct the quantitative trait loci(QTL)analysis using a set of 176 recombinant inbred lines(RILs)derived from a “Shannong 0431×Lumai 21”(SN0431×LM21)cross(SL-RIL).The 176 RILs and their parents were grown under hydroponic culture in greenhouse.The concentrations of N treatments were high N(HN),moderate N(MN)and low N(LN).Combined with a high-density genetic map,QTLs were located for N use efficiency traits at the wheat seedling stage.This should be helpful for gene cloning of related traits and molecular marker-assisted selection(MAS)in breeding programs.The main results are as follows:(1)The variation of phenotype showed that significant difference(p≤0.001)was detected between genotypes in all 14 targeted traits.Relative values of female parent SN0431 was obviously larger than those of male LM 21 for all traits under different N treatments.For RI lines,the wide variation ranges and transgressive inheritance under different treatments were detected.The variation coefficient for most traits(78.6%)was higher than 10%.The broad-sense heritability ranged 40.01-90.28 % for all traits except for RDW.The correlation coefficients were significant among the most traits.(2)QTL analysis was carried out for the 14 traits at the seedling stage under three N treatments,the result showed that a total of 168 QTLs were detected on 20 chromosomes except for 3D.The individual QTL could explain 3.30%-17.68% of the phenoty picvariations.A number of 53 SN0431 derived QTLs showed positive additive effects,whereas 115 LM21 dirived QTLs had negative additive effects.(3)A total of 46 RHF-QTLs were detected on chromosomes 1A,2A,2B,3B,4D,5A,5B,5D,6A、6B,6D and 7A for 13 traits except for SNCe.The average contributions ranged from3.71 to 16.16%.A mumber of 38 LM21 dirived RHF-QTLs showed negative additive effects,whereas 8 SN0431 dirived RHF-QTLs had negative positive additive effects.A number of 20 and 22 RHF-QTLs were found under a single and two N environment(s),respectively.Four RHF-QTLs(QTnue.4D.2、QSdw.5A、QSdw.5B-1.2、QRsdw.5D)were detected under all the three environments,HN,MN and LN,indicating they were affected diminutively by environment.(4)The cluster was defined as the co-location of RHF-QTLs for more than two traits in this study.Nine QTL clusters(C1-C9)were mapped on eight chromosomes: 3B,4D,5A,5B,5D,6B,6D and 7A,including 33 RHF-QTLs(75.00%).The increasing effects of QTLs come from LM21.The cluster C3 included eight RHF-QTLs(QRdw.5A,QRnce.5A.2,QSdw.5A,QSnc.5A,QSnue.5A,QTdw.5A,QTnc.5A.1,QTnue.5A)with the contributions of 6.47-11.40%.QSdw.5A was detected under all the three environments,QRdw.5A,QSnc.5A,QTdw.5A,QTnc.5A,QSnue.5A and QTnue.5A were detected under two environments,and QTnue.5A was detected only under MN. |
