Using Indica-Japonica Cross RIL Population To Locate QTLs Related To Salt And Alkali Tolerance In Rice

In order to explore the genetic mechanism of salt tolerance and alkali tolerance of rice,the genetic effects and quantitative trait loci(Quantitative Trait Locus,QTL)of rice under different concentrations of salt and alkali stress were analyzed.Recombinant Inbred Lines(RILs)constructed using high-quality indica rice Zhongyouzao 8(ZYZ8)as the male parent and salt-tolerant japonica rice Longdao 5(LD5)as the female parent.Controls and different concentrations of salt and alkali stress were set at the bud and seedling stages,respectively,for phenotype identification,genetic map construction,correlation analysis and QTL mapping.The main research results are as follows:1.Under salt and alkali stress,the growth of the parent and recombinant inbred line populations is inhibited,the germination potential,germination rate,seedling height,root length,number of roots,and dry matter weight are significantly reduced,the dead leaf rate,dead seedlings The rate and the relative saline-alkali damage rate of germination potential and germination rate both increased significantly,and as the stress concentration increased,the inhibition also increased.Under the salt and alkali stress,the phenotypic value of the female parent LD5 was smaller than that of the male parent ZYZ8,showing strong salt tolerance and alkali tolerance.2.Under salt and alkali stress,the average variation range of the salt and alkali tolerance related indexes of the recombinant inbred line populations at the bud and seedling stages were large,and there was a phenomenon of super-parent segregation.The skewness and kurtosis values of the population are mostly less than or close to 1,and most of the traits are consistent with or close to continuous normal distribution,which are consistent with the genetic characteristics of quantitative traits.3.Under salt stress,seedling height and root number,dead leaf rate and dead seedling rate all had extremely significant positive correlations,while dead leaf rate(10d)was extremely negatively correlated with seedling height and dry matter regeneration.Under alkaline stress,seedling height was extremely significantly positively correlated with root number and dry matter reversion,and significantly or significantly negatively correlated with dead leaf rate and dead seedling rate.The dead leaf rate was extremely significantly positively related to the dead seedling rate,while the dry matter weight was extremely significantly negatively related to the dead leaf rate and the dead seedling rate.4.Under salt stress,a total of 23 QTLs were detected at the bud stage,distributed on chromosomes 1,2,3,4,6,and 12,with LOD values ranging from 2.55 to 6.44,and changes in phenotypic contribution rates.The range is 7.40%~45.6%,of which there are 6 main QTLs.A total of 8 QTLs were detected at the seedling stage,which were distributed on chromosomes 1,4,6,and 7,respectively.Four new germination potentials,dead leaf rates,and dead seedling rates were found on chromosomes 3 and 6.QTL sites(q SGE3 a,q SGE3 b,q SDLR6,q SDSR6).5.Under alkaline stress,21 QTLs were detected during the bud stage,distributed on chromosomes 1,2,3,4,7 and12,with LOD values ranging from 2.79~10.58,and the phenotypic contribution rate changes.The range is 5.68% ~17.62%,of which there are 7 main QTLs,which are q AGE3 a,q AGE3 b,q AGR1,q ARL3 b,q ARN3 a,q ARN3 b,and q ADW2 a.A total of 5 QTLs were detected at the seedling stage,which were distributed on chromosomes 1,2 and 6.There is one main QTL.The QTLs(q AGR4a)related to the germination rate on chromosome 4 and the q ADL6 related to the dead seedling rate on chromosome 6 are newly discovered QTLs.6.There were clusters in the sites of salt or alkali resistance related traits detected.Under salt stress,there was one QTL in each of the RM13603-ID4 interval of chromosome 2 and the R3M10-STS interval of chromosome 3.Clusters,which contain 3 QTLs and 5 QTLs respectively;under alkali stress,there are 1 QTL clusters in the RM1358-RM300 interval of chromosome 2 and RM5480-STS interval of chromosome 3,including 3 QTLs and 7 QTL clusters were detected in the RM5480-TST region of chromosome 3 under both salt and alkali stress.It is speculated that QTLs in this region may be closely linked or controlled by the same gene.It may be due to the correlation between genes controlling different QTLs and other reasons,and further research is needed.