Elongation Mechanism Of Elongated Uppermost Internode Gene On The Uppermost Internode In Thermo-sensitive Genic Male Sterile Rice (Oryza Sativa. L)

Changxuan 3S(CX)is thermo-sensitive genic male-sterile (TGMS)eui mutants selected from Peiai 64S(PA)seeds irradiated with 350 Gy ⁶⁰Coγrays An elongated uppermost internode(eui)mutant exhibited notably rapid elongation of the uppermost internode at the heading stage;this is considered as a potential mechanism to eliminate panicle enclosure and has prospective application in hybrid seed production.In present investigation,we present the data of genetic,physiological and molecular studies of the eui mutant on the elongation of uppermost internode.The results were as follows:1.The length of uppermost internoe of F,hybrid between eui mutant CX and conventional semi-dwarf cultivars was showed as long as normal semi-dwarf parent in F,population and was recorded 3 normal semidwarf:1 eui tall in F₂ population,which indicated that eui mutant was governed by one pair of recessive gene.The allelic study showed that eui mutant and TGMS were independent inheritance.2.Dynamic elongation studies of uppermost internode were showed that the elongation stage of uppermost internode started from 6 days ahead anthese and ended anthese.The maximum elongation was recorded during 1～3 days ahead anthese. Cytological studies indicated that the elongation of uppermost internode was mainly attributed to the increase of cell number and cell elongation of middle and bottom section.The elongation of the uppermost internode in the TGMS eui mutant CX is mainly attributed to an increase in cell number and cell elongation,the latter being the more significant process.3,The studies of expression condition of eui mutant showed that the length of uppermost internode was negatively correlated with temperature of the stage from the formation of the pollen mother cell to the late uninucleate stage of the pollen grains and positively correlated with pollen fertility. The effects of fertility on the elongation of uppermost internode was mediated by the manipulation of endogenous gibberellin acide(GA₁,GA₃,GA₄)levels,the increase of gibberellin acide(GA₁,GA₃,GA₄)resulted in elongation of uppermost internode.However,no significant difference between eui mutant CX and wildy type PA was recorded for endogenous gibberellin acide(GA₁,GA₃,GA₄)The result suggest that eui mutant does not encoding gibberellin acide (GA₁,GA₃,GA₄)biosyntheses.Treatments of exogenous plant growth substances showed eui mutant CX was more sensitive to exogenous GA₃ than wild type PA.We presume that eui mutant may be gibberellin sensitive mutant.4.The differential expression genes in uppermost internode of TGMS eui mutant CX and wild type PA were compared using an oligonucleotide microarray that represents 36,926 unique genes.545 genes(0.925%)were identified as being differentially expressed between CX and PA at linear elongation phase.Among differential expression gene,362 genes(66.42%) exhibited up regulated,and 183 genes(33.58%)down regulated. Further analysis showed that there were significant number of genes responsible for signaling transduction,membrane Transport,cell growth and death,biosynthesis of secondary metabolites and carbohydrate metabolism which its implication for elongation of uppermost internode.