Phenotype Identification And Gene Maping Of Paa65 In Rice

The apical degeneration of rice?Oryza Sativa.L?is rather important to rice yield.So far,we hardly know molecular mechanism of rice apical degeneration an dcorresponding molecular regulatory network.Therefore,it is very important to stud ythe molecular genetic mechanism of panicle degradation.In my study Yixiang 1B was induced by a methyl sulfonate?EMS?,and obtained a panicle degeneration mutant,and named paa65?panicle apical abortion 65?.The panicle degeneration mutant was controlled by rice gene LOC_Os02g07960 using gene mapping and clone.The main study results are as follows:1.Phenotypic analysis of the mutant paa65 showed that the top spikelets and branches of the paa65 were degenerated and the rate of degradation was 50%;panicle length and seed setting rate per panicle were significantly lower than in wild type.2.Genetic analysis showed that the ear degeneration trait of mutant paa65 was controlled by recessive single gene,and the gene was located between chromosomes RM12368 and RM5622 by gene mapping.The apical degeneration of paa65was controlled by gene LOC_Os02g076 according to further analysis,and the base mutation from G to A in the 4th exon of LOC_Os02g07960,and leading to early termination of translation.3.When the ear length of the mutant was 12cm and 16cm,respectively,the paraffin sections of the young panicles were observed.At 12cm,there was nosignificant difference between the wild-type spikelets and the paa65 spikelets.At 16cm,the cross-sectional profile of the paa65 spikelets was atrophied.Observation of flower organs showed that paa65 presented shrink in 10 days before flowering.Besides,the results showed that paa65 had no fertile pollen grains using potassium iodide?I₂KI?staining to different development periods of flower.4.According to cytological examination,the results showed that there was a large amount of ROS accumulation in the degraded part of paa65 and programed cell death.Besides,the result also showed that the degenerate phenotype of the panicle derived from differential regulation of many different hormone levels.5.Gene LOC_Os02g07960 in ear was higher expression after 12 cm than inthe wild type.Besides,LOC_Os02g0796 belong to constitutively expressed by analysis of expression profile.Thus,we speculate that LOC_Os02g0796 plays a regulatory role in ear development.6.According to staged sowing in the field,and under different daily average temperature conditions,the results showed that degradation rate was related to temperature.