Improvement Of Herbicide Resistance Of Rice Restorer Lines Yihui1577,Hua84 And Guanghui998

Rice is one of the major food crops in the world.The growing area,total yield,and yield per unit area of rice are in the primacy comparing with other crops,which has made great contribution to China’s food security.Weed not only has a serious impact on the yield and quality of rice,but also costs more money and manpower.Traditional weeding does not meet the requirements of modern agriculture.Application of transgenic rice with herbicide-resistant can not only effectively control weeds in paddy field and reduce labor costs,but also solve the purity problem of rice hybrids and enhance the yield of hybrid rice.In this study,a series of herbicide-resistant restorer lines with ideal agronomic traits had been cultivated through MH63-EPSPS as the donor parent to backcross with 3 elite restorer lines(Yihui 1577,Guanghui 998,Hua 84),in which 9 newly cultivated lines(Yihui 1577EP-1～3,Guanghui998 EP-1～3,Hua 84EP-1～3)were selected to use in following experience.Sixty hybrids were mated by NCⅡ design with 9 restorer lines as male and 5 popular sterile lines(Hongxiang2A,Y58 S,Guangzhan63-4S,Hua1015 S,Tianyuan6S)as female.The application potential of these newly-cultivated restorer lines were comprehensively evaluated in term of herbicide resistance,molecular detection and tissue expression patterns of EPSPS,and combining ability.The main results are as following:1.The identification of herbicide resistance indicated that the resistance of the newly developed 9 restorer lines reached above 94%,which was consistent with the molecular detection of target gene EPSPS.The hybrids derived from above herbicide-resistant restorer lines and conventional male-sterile lines displayed the separated herbicide-resistance in the ratio of 1:1.2.The quantitative PCR analysis of 9 newly-cultivated restorer lines showed that EPSPS gene was mainly expressed in stem,leaf and young spikelet.The expression level of EPSPS in stem was about 500 to 2000 times of that of non-transgenic control(Minghui63),10 000 to 54 000 times in leaf,and 60 to 150 times in spikelet.The expression level of EPSPS gene in transgenic seed was very small(0.2 to 1.1 times of the control).3.The correlation analysis of the agronomic traits of the 60 hybrids showed that the correlation coefficients among these traits ranged from-0.68 and 0.89.The significant positive correlation was tested between YP and PL,NFP,SSR,KGW respectively;and similar correlation was also tested between DS and PH,KGW;SSR and PL,NFP,YP respectively.4.The combining ability analysis of the main agronomic traits of the tested hybrids showed that:(ⅰ)The significant difference of GCA between female parents for all other nine agronomic traits(SSR,DS,PH,PN,NGP,KGW,NFP,PL,and GD)except for YP were detected.Among the sterile lines,Hongxiang 2A had the highest GCA effect in YP and NFP;Guangzhan 63-4S had the highest GCA effect in traits such as SSR,KGW,DS,and PH,but the most negative effect of GCA in PN;Y58S had the highest GCA effect in PN and PL;Tianyuan 6S had the most negative effect of GCA in DS and PH,and the highest GCA in GD and NGP.(ⅱ)The significant difference of GCA between male parents for all traits were detected,in which Hua 84EP-3 had the highest GCA effect in GD and NGP,Guanghui 998EP-1 had the highest GCA effect in SSR.(ⅲ)The significant difference of SCA between sterile and restorer lines were detected for all other traits except for PN and PH.(ⅳ)The newly-developed herbicide-resistant restorer line had similar GCA effect with original restorer receptor for most of agronomic traits,meaning that it is feasible to improve the herbicide resistance of these restorer lines on the premise of keeping the excellent agronomic traits.5.The combining ability analysis of the quality traits of hybrids showed that:(ⅰ)For the GCA of sterile lines,Hongxiang 2A had the highest GCA effect in BR,MR,HR,CGR,CD and GS;Guangzhan 63-4S had the most negative effect of GCA in CGR and CD.(ⅱ)For the GCA of restorer lines,Yihui 1577 had the highest GCA effect in MR and HR;Hua 84EP-2 had the most negative effect of GCA in CGR and CD.(ⅲ)For the SCA between sterile and restorer lines,Y58S/Yihui 1577 had the highest SCA effect in BR;Hua 1015S/Yihiu 1577 had the highest SCA effect in MR;Tianyuan 6S/Hua 84EP-1 had the highest SCA effect in HR;Hua 1015S/Hua 84EP-3 had the most negative effect of SCA in CGR and CD.6.Some superior hybrids had been selected preliminarily with herbicide resistance screening,analysis of combining ability,investigation of agronomic and quality traits.The chosen combinations are as follows: Tianyuan 6S/Hua 84EP-1,Hongxiang 2A/Hua 84EP-3,Y58S/Hua 84EP-2,and Hua 1015S/Hua 84EP-2,whose quality reached the national level 3,and whose YP above the control cultivar(Fengliangyou 4).Especially the yield of Tianyuan6S/Hua84EP-1 was the highest,and 23.54% higher than that of Fengliangyou 4.