Phenotypic Analysis And Genetic Mapping Of A Yellow Dwarf Mutant In Rice (Oryza Sativa L.)

The leaf color mutants are important materials ofr rice functional genomics research, it can be used as a special marking character and it has widely application value in production practice. We found a yellow-dwarf mutants, named yd-158R. Compared with wild type, this paper respectively for yd-158R, chlorophyll content determination of main agronomic traits, hormone response, electron microscope has carried on the investigation and study analysis, based on the genetic analysis of the characters, the mutation for the gene location, for the purpose of gene cloning and mutation molecular mechanism study to lay the foundation. The results are as follows:1. Phenotype characteristics and agronomic traits of the yd-158R mutant:Compared with wild type 158R yd-158R mutnt leaf color stays yellow-green at seedling stage, late leaf etiolation, from the leaf base to tip etiolation degree aggravating gradually, main agronomic traits such as plant height, spike length, grain number per panicle, seed setting rate,1000-grain weight, the effective panicles, grains and other indexes dropped significantly.2.According to the determination of photosynthetic pigment content compared with wild type 158R, mutant yd-158R in the total chlorophyll content of seedling stage, chlorophyll a and chlorophyll b and chlorophyll a/b fell by 74.14%,74.28%,73.53% and 3.03% respectively, carotenoid content increased by 38.38%; At heading stage total chlorophyll content, chlorophyll a and chlorophyll b, chlorophyll a/b, carotenoids five index fell 93.73%,93.99%,92.60%,17.47% and 20.55%,. The results show that the yellowing mutant phenotype is caused by the decline in photosynthetic pigment content, and leaf etiolation degree along with the growth period as it significantly influence to late.3.Photosynthetic indexes:The yd-158R net photosynthetic rate, stomatal conductance Gs,Pn, transpiration rate compared with wild type Tr fell by 78%,95% and 78% respectively at seedling stage,; Mutant net photosynthetic rate of Pn, transpiration rate, stomatal conductance Gs,Tr compared with wild type fell by 87%,86% and 87% respectively at heading stage.That mutant photosynthetic efficiency severely affected, leading to a series of changes in agronomic traits.4.The electron microscopy structure of the yd-158R mutant leaf:The yd-158R mutant chloroplasts were different degrees of damage, and chloroplast has quite a number and size of starch grain accumulation, the nucleus quality color deepened, cell membrane system is imperfect, of which the most tip part, almost all the chloroplast grana degradation, with a large number of starch grains in cells, and the situation of the central and leaf blade base gradually ease, yd-158R to speculate that the mutant associated with growth and development process of the chloroplast.5.The response to exogenous hormone analysis found:The dwarf of yd-158R has nothing to do with gibberellin GA approach, it does not belong to the gibberellin GA synthesis defect types, also do not belong to the gibberellin GA insensitive type; yd-158R isn't a BR mutant, yd-158R compared with wild type dwarf has nothing to do with the BR signaling pathways, at the same time, the light can make the phenotype of yd-158R.6.Genetic analysis:By reciprocal crossing the yd-158R mutant with R23 and Rshu, and by analyzing the F1 and F2,we got the result that yellow-dwarf mutation phenotype of the yd-158R mutan was controlled by a pair of recessive nuclear genes.7.Gene location:using the yd-158R and Rshu build F2 populations, the yd-158R for positioning, in the end of the chromosome 9 long arm in D17 InDel markers and SSR markers RM1026 About 597 KB of area, and the two markers of genetic distances were 0.01 cM and 0.41 cM, the band has not been reported related gene mapping and cloning, so think yd-158R is a new leaf color control gene.8. By sequencing found yd-158R mutant in front of the gene LOC Os09g38320 coding region ATG 151th base occurs replacement(T->G). The gene mapping of the mutant yd-158R:Using the transcriptome sequencing analysis of differentially expressed genes analysis, found gene LOC_OS09g38320 increase expression in the mutant. Presumed this gene for possible target genes.