| Wheat(Triticum aestivum L.)is one of the most important food crops in the world,which is very important to ensure high and stable yield and maintain world food security.In the 1960 s,the successful introduction of the Rht-B1 b and Rht-D1 b in wheat breeding led to a decrease in plant height and a significant increase in wheat yield,which was defined as the “Green Revolution” in the world.Peduncle length,part of plant height,plays an important role in wheat structure,the reasonable peduncle length is the key to maintain wheat high yield and optimize wheat plant type structure.But so far,the research on RhtB1 b and Rht-D1 b mainly focused on the effect of plant height,the effects on the peduncle length and other important agronomic traits are still unclear,which limits the precise application of Rht-B1 b and Rht-D1 b in modern breeding practice.In this study,we comprehensively observed the main agronomic traits of wheat in eight environments of 406 wheat accessions,the results of genome-wide association analysis showed that Rht-B1 b and Rht-D1 b are the two main haplotypes regulating plant height and peduncle length in modern wheat.A new QTL,QPL＿6D.1,was identified and verified on chromosome 6D,which significantly regulated the peduncle length.The pleiotropy of RhtB1 b,Rht-D1 b and QPL＿6D.1 on agronomic traits of wheat and the selection and utilization in modern breeding was systematically analyzed based on population genotype,phenotype and spatial and temporal distribution data.In addition,the responses of Rht-B1 b and RhtD1 b to different meteorological factors and predicted the application prospects and risks of Green Revolution genes in global warming scenarios were explored by integrating meteorological information from multiple environments and using multiple regression analysis.The main results are as follows:1.The Rht-B1 b and Rht-D1 b were significantly correlated with the plant height and peduncle length,and had pleiotropic effects on wheat agronomic traits,both Rht-B1 b and Rht-D1 b also significantly decreased the total tiller number,productive tiller number,flag leaf length and angle,but significantly increased the flag leaf width.In addition,compared with Rht-B1 b,the Rht-D1 b displayed a stronger effect.Moreover,Rht-D1 b significantly decreased spike length and the spikelet spacing,but significantly increased thousand kernel weight,kernel length and width,the thousand kernel weight was increased by about 2 grams on average.Rht-B1 b significantly increased the fertile spikelet number and kernel number per spike,which result in about 4 kernels increase per spike,which indicated that the Green Revolution genes had significantly different effects on wheat yield increase.2.The QPL＿6D.1 was significantly associated with the peduncle length,but the effect of QPL＿6D.1b on reducing plant height and peduncle length was not dependent on Rht-B1 b and Rht-D1 b,and there was an additive effect between QPL＿6D.1b and Rht-B1 b and RhtD1 b,which could be freely combined to regulate the plant height of wheat.In addition to decreasing plant height and peduncle length,QPL＿6D.1b also significantly decreased tiller number,flag leaf length and flag leaf area,but significantly increased kernel number per spike,suggesting that QPL＿6D.1b may be involved in the regulation of these traits.3.Rht-B1 b and Rht-D1 b were widely used in modern wheat varieties worldwide,and the frequency of Rht-B1 b and Rht-D1 b increased significantly after 2000,,especially RhtD1 b,which increased from 45.9% to 78.1%,and mainly concentrated in Yellow and Huai wheat zone,while the Rht-B1 b was preferred in Yangtze River wheat zone in China.QPL＿6D.1b were mainly selected in Yellow and Huai wheat zone and Yangtze River wheat zone in China but not in introduced cultivars,which together with Rht-B1 b and Rht-D1 b genes regulate the plant height and peduncle length of wheat in China.4.Multiple regression analysis between environmental factors and wheat traits based on meteorological information from multiple environments showed that the temperature was one of the most important environmental factors affecting wheat traits.With the increase of average temperature,the plant height,tiller number,flag leaf area,total spikelet number and thousand kernel weight all decreased significantly,but the flag leaf angle increased significantly.Compared with the accessions without Green Revolution genes,the accessions with Rht-B1 b or Rht-D1 b were more severely affected with the increase of temperature and had more severe deterioration in plant structure and yield related traits.Which indicates that the use of Green Revolution genes in the future will require more improvement to continue to exert their significant yield increase effect.In conclusion,the genetic loci Rht-B1 b,Rht-D1 b and QPL＿6D.1b of plant height and peduncle length significantly changed the plant structure of modern wheat,and had significant effects on many agronomic traits of modern wheat.These results provide basic data for further understanding the contribution of Green Revolution genes to current wheat breeding and their application in future global warming scenarios,and provide important references for accurate use of Green Revolution genes to improve wheat agronomic traits. |
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