Ling Yinghua

Prediction of hybrid grain yield performances in Indica Rice (Oryza sativa L.) with effect-increasing loci

One hundred and fifty-one rice hybrids produced in two sets of half-dialell crosses and their parents (13 cytoplasmic male sterile lines and 19 restorers) were used to predict the F1 performances of seven yield traits through the parental genetic distances (GD) based on SSR markers. The positive loci (PL) and effect-increasing loci (IL), which were screened from SSR polymorphic loci by the F1 traits of 32 parents, together with total loci (TL), were utilized to estimate parental GD and the models were found to predict the traits of hybrids derived from different parents, fixed parents, and different environments, respectively. The results were as follows: (1) 550 polymorphic loci were detected from 174 SSR markers: a dendrogram based on these loci could separate all the sterile and restorer lines used in the present study, which indicated that parental genetic diversity of F1 was large; (2) the correlations between F1 traits and parental GDs based on IL ranged from 0.61 to 0.87 with a mean of 0.76, and they were higher than those on TL or on PL; (3) predictions based on IL for F1 traits (except grain weight per plant) derived from different environments were ideal, but worse for F1 traits derived from different parents; and (4) IL was more effective than TL and PL in predicting traits of F1 with fixed parents, and predictions for fixed restorer combinations were more effective than those for fixed sterile line combinations. These results should facilitate molecular prediction for hybrid yield and other traits by means of both elite sterile and restorer lines.

Additive effects and epistasis effects of QTL for plant height and its components using single segment substitution lines (SSSLs) in rice.

Plant height is a typical quantitative trait that is liable to be influenced by genetic backgrounds and environments.As a novel research material,single segment substitution lines and double segment pyramiding lines in rice will make QTL identifica-tion and epistasis analysis more accurate because of diminishing the interference of genetic backgrounds among plants.In this study,Detection of QTLs controlling plant height and its components and analysis of epistasis effects were done with 16 secon-dary single segment substitution lines and 15 double segment pyramiding lines derived from crossing of primary SSSLs by ran-domized blocks design.The main results showed that 11 QTLs were detected and distributed on chromosomes 4,6,and 10,of which three QTLs controlling plant height,one QTL coffering length of the first inernode from the top,two QTLs harboring length of the second internode from the top,two QTLs for length of the third internode from the top and three QTL controlling length of the fourth internode from the top were included.Twenty-three digenic interactions were detected for plant height and its components,of which 7 interactions occurred between two loci both not having main effects on the traits,and 16 interactions each involved one locus having a main effect at the single-locus level and another locus that did not show significant effect at the sin-gle-locus level.The results indicated that both additive effects of QTL and epistasis effects between QTLs were important genetic components.Efficiency of QTLs identification and epistasis effects analysis between QTLs could be improved using secondary single segment substitution lines and double segment pyramiding lines derived from crossing of primary single segment substitu-tion lines.

Genetic analysis and molecular mapping of a yellow green leaf gene (YGL4) in rice (Oryza sativa L.).

A leaf color mutant was obtained by EMS treating seeds of restorer line Jinhui 10,this mutation showed complete yellow green leaves during the life,and could be regenerated and inherited stably according to the observation of 5 generations.The content of its total chlorophyll ranged from 2.01 to 2.28 mg g-1,which was only 38.2%to 50.5%of the original parent.Compared with the original parent,the mutation had no significant difference in the traits of main panicle length,first branch number,filled grain number of main panicle,seed setting rate and 1000-grain weight,except the effective panicle and plant height which were decreased significantly.Genetic analysis of F2 populations confirmed that the mutational character was controlled by a single recessive nuclear gene,temporarily designated as YGL4.The gene was mapped between two microsatellite markers RM3123 and RM590,with genetic distances of 7.6 and 7.8 cM to the two markers respectively.New microsatellite markers were designed between RM3123 and RM590,and the YGL4 gene was final mapped between RM1162 and RM7093,with genetic distances of 1.8 and 4.0 cM to each of them respectively.This result provided a foundation of molecular marker-assisted breeding and map-based cloning of YGL4 gene.