Breeding Of New Rice Germplasm With High Yield,good Quality And Resistant To Planthoppers Based On Molecular Design

In the past decades,the development of food production has made remarkable achievements.However,with the continuous growth of the population,the decreasing per capita arable area and the changing climate,food security remains a serious problem.As a result,the yield appeal of rice,one of the world’s three major food crops,remains a focus for scientists.Today,in addition to yield,the pursuit of resistance and quality is also urgent.Quality is an important factor that determines the consumption market,and resistance is an important prerequisite for food safety and production safety.Therefore,the synergistic improvement of yield,resistance and quality will be the ultimate goal of scientists.Conventional breeding methods often show a series of problems such as low efficiency and poor accuracy,which are not conducive to the realization of this breeding goal.The theory of molecular design breeding and its practical application provide a new strategy to achieve this goal.According to the molecular design breeding,the main genes controlling yield,resistance and quality can be selected and gathered efficiently,and their genetic background can be selected to a certain extent,so as to quickly achieve the breeding goals of high yield,high resistance and high quality.For this study,three new rice germplasms with high yield,high resistance and good quality were bred with 9311 as the background parent by rational molecular design.The results are as follows:1.Fifteen genes related to yield,resistance and quality were selected as target genes,and molecular design was carried out with 9311 as the background material.Through a series of screening,three new rice germplasms(MD1,MD2,MD3)with high yield,high resistance and good quality were successfully bred.MD1 and MD2 pyramided all target genes except SBE3.MD3,on the other hand,aggregates all the genes of interest(High yield genes: Gn8.1,APO1,Ghd7,Ghd8,Gn1 a,Cooking and eating quality genes: Wx,ALK,SBE3,SSIV-2,SSIII-1,Appearance quality genes:GW7,q SW5,GS3,Brown planthopper resistance genes: Bph6,Bph9).2.The three selection lines of MD1,MD2,MD3 had a good plant type and inherited the high yield characteristics of the large-panicle donor parent 1880,with obvious yield advantages.Compared with the high-quality rice donor parent YZM1,the yield per plant of MD1,MD2,MD3 increased by 72.1%,60.2%,75.0%,respectively.Compared with cyclic parent 9311,the yield per plant increased by30.4%,21.4%,32.6%,respectively.This indicates that the yield of molecular design breeding lines has been greatly improved and the expected goal of high yield has been realized.3.The Bph resistance ability of MD1,MD2,MD3 was greatly improved compared with that of the sensitive control 9311,and was also improved compared with the resistant donor parents Luoyang 6 and Luoyang 9.The resistance scores of MD1 and MD3 were 1.5 and 1.8,respectively,which were significantly better than that of Luoyang 6 and Luoyang 9(3.5),while the resistance scores of MD2 were 2.8,which were better than that of the resistance control.4.The three molecular design breeding lines MD1,MD2,MD3 inherited the quality characteristics of YZM1 and improved the appearance quality and cooking quality.As for the gel consistency,the three selection lines were similar to donor parents 1880 and YZM1.In terms of grain length and length-width ratio,the three lines were higher than 9311,but significantly inferior to YZM1.For the chalkiness grain percentage,the three lines perfectly inherited the low chalkiness characteristic of YZM1,and all of them were significantly improved compared with 9311.The amylose content of the three lines was significantly decreased compared with that of9311,which was similar to that of YZM1 and 1880.In terms of gelatinization temperature,the three strains were better than 9311 and 1880,and had no significant difference with YZM1In conclusion,we successfully bred three new rice germplasm with high yield,high resistance to Bph and good quality through reasonable molecular design,which will be acted as valuable resourses for subsequent molecular design breeding.