The Studies On The Rule Of Uppermost Internode Elongation In PTGMS Rice With Eui Gene

Panicle enclosure is a typical phenotype of almost allmale-sterile lines, which greatly reduces seed production ofhybrid rice due to its blocking of normal pollination.Elongated uppermost internode(eui) gene can reduce oreliminate panicle enclosure, which if very useful in hybrid riceresearch. By now the rule and mechanism by which eui genepromotes the elongation of uppermost indernode in PTGMS ricewas not reported yet. In this paper, while Pei' ai 64S was usedas control, the elongation change, length and number of cellsof in uppermost internode in eui mutant PTGMS rice-Changxuan3S were analyzed to study the rule of uppermost internodeelongation; the content of endogenesis hormones in youngpanicles and uppermost internode were analyzed and thetreatments of exogenous hormones were taken to study therelationship between the uppermost internode elongation andplant hormones; the expression levels of genes involved ingibberellin biological synthesis and signal transduction wereanalyzed using the method of semi-quantitative RT-PCR. Themain results were as follows:(1) The elongation period of uppermost internode in euimutant PTGMS rice-Changxuan 3S was 6 days before anthese to theday of anthese. The increase of cell number was observed inearly elongation stage, in which the elongation per day was notsignificant. The fast elongation stage was 1-3 days beforeanthese, and the elongation was mainly attributed to theincrease of cell elongation of middle and bottom section. Nosignificant difference between the cell lengths of Changxuan3S and Pei' ai 64S was observed in early elongation stage, whilethe difference became significant in the fast elongation stage. normal pollen fertility could promote the cell elongation infast elongation stage, and the eui gene and normal pollenfertility has the synergic action to each other in promotingcell elongation in the fast elongation stage.(2) When remove the young panicles in the fast elongationstage, the lengths of uppermost internodes were shorter thanthe ones without the removal treatment. The earlier thetreatment was taken, more significant the effect was. Comparingthe elongation of uppermost internode after the removaltreatment, the later the treatment was taken, the shorter thelength of elongation was. The length of uppermost internode inChangxuan 3S elongated after removing the young panicles in thefast elongation stage was much longer than the ones in Pei' ai64S. Determination of the content of endogenesis hormones inChangxuan 3S and Pei' ai 64S in the fast elongation stage showedthat in three kind of active gibberellins, the content of GA₁was the highest one while the content of GA₃ followed, and theone of GA₄ is lowest. But there was no significant between thegibberellins contents in Changxuan 3S and Pei' ai 64S, and thesame with contents of IAA, ABA and Z. Treatment of exogenoushormones indicated that IAA had no significant effect touppermost internode elongation and ABA had some effect ofinhibition; GA₃ had promoting effect to the elongation ofpanicles extension, uppermost internode, the second internode.and the length of stem. The promoting effect increased with theincrease of concentration of GA₃ At low concentration(0.01μM), Changxuan 3S showed reaction to GA₃, the paniclesextension and length of uppermost internode was significantlylonger than. the control while Pei' ai 64S didn't showed thesensitivity. The result indicated that Changxuan 3S is a GA₃ sensitive mutant.(3)OsGA3OX1, which plays a pivotal role in gibberellinbiological synthesis, Slr1, which induces the gibberellindownstream reaction, and Gid1, a gene of gibberellin receptorexpress in both Changxuan 3S and Pei' ai 64S. The expressionlevel of OsGA3OX1 was a little higher in Changxuan 3S than inPei' ai 64S, the one of Slr1 had no difference in in Changxuan3S and Pei' ai 64S while the expression level of Gid1 wassignificantly higher in Changxuan 3S than in Pei' ai 64S.