Effects Of Fragrant Gene Badh2 On Agronomic Traits And Temperature Stress Resistance At Seeding Stage In Rice

In order to explore and utilize rice fragrant gene and its germplasm resources,a new functional molecular marker of rice fragrant gene was developed in this study;Using this marker,five pairs of sister rice lines with the same plant leaf morphology were selected from909 stable genetic lines of rice breeding;The differences of agronomic characters between the five pairs of sister lines of fragrant type and non-fragrant type were compared and determined;The differences of heterosis between them and 40 groups of hybrid combinations crossed with four two-line male sterile lines were compared;The contents of MDA and Pro,the enzymes of POD,SOD and CAT were compared under different temperature stress treatments;The relative expression levels of Badh2,P5CS,Pro DH and other genes were compared,and the main results were as follows:1.According to the mutation sequence characteristics of Badh2 in rice and the poor conservation of primer 5’end in PCR amplification,three primer markers of Fgr-FF,Fgr-NF and Fgr-R were developed.The marker amplified a 115 bp characteristic band in fragrant rice,a 156 bp characteristic band in non-fragrant rice,both 115 bp and 156 bp characteristic bands in heterozygous rice at the same time;The three primer functional markers were used to detect fragrant genes in 30 rice varieties and 92 F₂plants.The detection results were consistent with the identification results of two phenotypes.The PCR amplification of the three primer molecular marker method can accurately,clearly and quickly detect homozygous,heterozygous and three genotypes of fragrant genes in rice plants by agarose gel.2.Under the treatment of low temperature,normal temperature and high temperature,the average values of seedling height and root length of five fragrant rice lines were greater than those of five non-fragrant rice lines;The contents of MDA and Pro and the average activities of POD,SOD and CAT in high and low temperature stressand the average contents of MDA and pod enzyme activities in low temperature stress were higher than those in normal temperature treatment,while the average contents of MDA and Pod enzyme activities in high temperature stress were lower than those in normal temperature treatment.Under high temperature stress,the MDA content of the five non-fragrant rice lines was higher than that of their water rice fragrant sister lines;The Pro content of the five fragrant rice lines was higher than that of their non-fragrant sister lines.Under the treatment of low temperature stress,the pro content of five non-fragrant rice lines was higher than that of their water rice fragrant sister lines;The POD activity of the five aromatic rice lines was higher than that of their non-fragrant sister lines;The cat activities of four non-fragrant rice lines were higher than those of their water rice fragrant sister lines.3.Under low temperature stress,the relative expression of genes in five pairs of fragrant and non-fragrant sister lines of rice was OSPro DH>OSP5CS>Badh2 from high to low;Under high temperature stress,the trend of relative expression of genes was Badh2>OSP5CS>OSPro DH.Moreover,under low temperature stress,the relative expression of OSPro DH in five non-fragrant rice lines was significantly higher than that in five fragrant rice lines,which was consistent with the trend of Pro content under low temperature stress.The relative expression of Badh2 in five pairs of fragrant and non-fragrant sister lines of rice under low temperature and high temperature stress was positively correlated with the relative expression of OSP5CS;The relative expression of OSPro DH was negatively correlated with the relative expression of Badh2 and OSP5CS（P<0.01）.4.The average values of the five agronomic characters of the five fragrant rice lines tested,such as the number of grains per panicle,the total number of grains per panicle,1000grain weight,seed setting rate and yield per plant,were greater than the average values of the five non-fragrant rice lines.The results showed that the variance of general combining ability and special combining ability of agronomic characters such as plant height,panicle length,number of effective panicles,1000 grain weight and yield was significantly higher than that of special combining ability,indicating that these five characters were mainly affected by additive effects;The variance of special combining ability of 8 agronomic characters such as plant height,ear length,number of effective ears,number of grains per ear,total number of grains per ear,1000 grain weight,seed setting rate and yield per plant was significantly higher than that of general combining ability,indicating that these eight characters were mainly affected by dominant effect and epistatic effect.5.The results of combining ability and heritability of 40 hybrid combinations of five pairs of fragrant and non-fragrant sister lines in rice showed that the two-line male sterile lines L21S and 101-S showed better general combining ability in agronomic characters,and the two pairs of fragrant and non-fragrant sister lines,such as W3046（fragrant）and W3047（non-fragrant）,W3490（fragrant）and W3491（non-fragrant）,had higher general combining ability in effective panicles,seed setting rate and yield per plant;The six hybrid rice combinations configured by L21S/W3047（fragrant）and L21S/W3046（non-fragrant）,L21S/W3490（fragrant）,L21S/W3491（non-fragrant）,101-S/W3047（fragrant）and 101-S/W3046（non-fragrant）can be selected as seedling combinations for high-yield and high-quality breeding and production application.