Identification And Utilization Of High Quality Disease Resistant Glutinous Rice Materials

The hot spots of hybrid glutinous rice breeding are high yield,high quality,disease resistance and lodging resistance.In this study,a backcross genetic population was constructed,and bulk segregant analysis（BSA）was employed to mine the QTLs affecting the starch amylose content of glutinous rice in wxwx genetic background.The new glutinous rice germplasm with high yield,disease resistance,low amylose content and high alkali spreading value were identified and evaluated in the constructed backcross genetic population by combining traditional techniques with molecular breeding.The incomplete diallel cross（NC-II）was employed to construct the genetic population contained parents and 20 F₁ hybrids.The breeding utilization value of parents and hybrid combination on yield and quality traits were evaluated,The results provided scientific basis for the effective utilization of waxy rice heterosis.The main results are as follows:1.In present study,the BC₂F₄and BC₂F₅ backcross populations of Pinnuo R191/JGSM//JGSM//JGSM were constructed and SNP genotyping of mixed pools of parents and heterozygote populations with high and low amylose content was performed using BSA and GSR40K rice microarray in wxwx genetic background.The candidate gene segments associated with amylose content were mapped to 0.04～0.37 Mb on chromosome 5 and17.53～24.09 Mb on chromosome 12.On chromosome 12,fourteen polymorphic SSR markers and SNP markers were screened and Inclusive Composite Interval Mapping（ICIM）was used to construct genetic linkage maps in three different generations using QTL Ici Mapping software.The results showed that the percent contribution of the QTL q AC12 affecting amylose content in N21774-A24633 of chromosome 12 was 14.10%,and the additive effect value was-0.11.In addition,For the analysis of the candidate QTL at the end of chromosome 5,according to the genotyping of marker Zc I5＿167 in the predicted interval and phenotyping analysis results,the percent contribution of the candidate QTL to amylose content was 9.83%,and the additive effect value was 0.156.2.Combining traditional techniques with molecular breeding,the resistance genes,amylose content and alkali spreading values of 107 lines of BC₂F₄ generation in Hainan in 2021,BC₂F₅in Fuzhou in 2022 and BC₂F₅in Putian in 2022 were identified.Sixteen excellent waxy rice lines with resistance genes,medium resistance level,amylose content less than2%and alkali spreading value more than 5 were selected.The yield,amylose content,resistance and important agronomic traits of seven of the above lines were analyzed by a randomized block design method,using indica glutinous rice cultivars“Zhenzhunuo”,“Jinnuo No.6”and white rice parent“JGSM”as the control.The results showed that the rice grain yield of the seven excellent lines ranged from 516.29 kg/mu to 614.43kg/mu.Among them,the yield of X-104 was the highest,reaching 614.43kg/mu,and the yield of X-27 was 597.34 kg/mu,which was significantly more than the three controls.These two lines exhibited dwarf phenotype and carried Pi-1 and Pi-k^h as well as Pi-1,Pi-9 and Pi-k^hresistance gene,respectively.Besides,the amulose contents were 1.71%and 1.68%,and the alkali spreading values were 6.75 and 6.13,due to the ALK gene they contained.In conclusion,these two lines have high utilization value in conventional glutinous rice breeding.3.The cross among the above five representative glutinous rice lines and four glutinous rice sterile lines was designed by an incomplete diallel hybridization（NC-II）,generating the combination including parents and their 20 hybrid progenies.DPS software was employed to analyze the combining ability of main yield traits and rice quality.The results showed that the majority of yield traits,amylose content and alkali spreading values of the hybrid generation of glutinous rice were controlled by the additive effects of parents or non-additive effects between combinations.The glutinous rice restorer line X-27 was beneficial to improve the yield and rice quality of the hybrid progeny,except for its positive effect on the general combining ability（GCA）of plant height.X-57 was helpful to reduce plant height and amylose content of progeny and improve the yield and the alkali speading value of progeny.X-104 exhibited high yield and good quality,but was not conducive to the utilization of heterosis.The progeny of Nuo 326S/X-107,Minnuo 2S/X-57 and Minnongnuo 6A/X-107 exhibited better lodging resistance and the SCA of Nuo 326S/X-27,Nuo 326S/X-27 and Nuo326S/X-107 was higher in yeild.Howevr,Nuo326S/X-27,Minnuo 2S/X-27 and Mingnuo 208A/X-41 had high SCA in amylose content,and Minnuo 2S/X-41,Minnongnuo 6A/X-107 and Minnuo 2S/X-107 had better SCA in alkali spreading values.Moveover,Minnuo 2S/X-41 and Minnuo 2S/X-107 had over-parent heterosis and copetitive advantages in yeild,plant height,amulose content and alkali spreading values.These conbinations have good application value in hybrid glutinous rice.The variance contribution rate analysis of genotype and combining ability showed that the yeild and quality of the glutinous rice were complex traits,among which the effective panicle number,panicle length,1000-grain weight,ratio of length to width,yield per plant,amylose content and alkali spreading value were closely related to the glutinous rice restorer lines.The broad heritability（h_B²）of each trait varied from 14.72%to 53.99%,and the narrow heritability（h_N²）varied from 10.25%to 43.07%.The heritability of each trait was low and easy to be affacted by environment.A large number of matching groups are needed to cultivate special glutinous hybrid suitable for different purposes.In conclusion,on the basis of preliminary mapping of QTLS affecting amylopectin content of waxy rice,a series of excellent waxy rice conventional lines were selected by combining conventional and molecular techniques,which have a broad application prospect in the utilization of waxy rice heterosis.