水稻穎花相關基因之研究

Abstract

水稻穎花大小與形態可能限制榖粒發育，間接影響產量；因此，本試驗期望找到與水稻穎花發育相關的基因。從劉(2003)所建立水稻穎花發育相關候選基因庫中，挑選6個基因：salT基因(salt-induced protein)、GA-SPY基因(gibberellin action negative regulator SPY-related protein)、U2AF基因(U2 snRNP auxiliary factor，small subunit-related protein)、kinesin-like基因、DnaJ-like基因、及EF hand基因，以水稻正常型穎花(SLP/SLP)、小穎花突變體(SLP/slp)及內外穎退化突變體(slp/slp)之葉片及1~4公分幼花序為材料，利用Real-Time RT-PCR分析，發現salT基因在突變體幼花序中大量表現。因此，進一步分析salT基因在水稻不同器官中的表現，發現salT基因在水稻中僅有一個拷貝數，葉鞘salT基因表現量比葉身高，在SLP/SLP幼花序中幾乎不表現，但在slp/slp幼花序中表現量極高。salT基因在水稻中僅有一個拷貝數；本試驗進一步利用農桿菌轉殖法將salT基因轉殖到TNG67及SLP/SLP品系中，分析salT基因對轉殖株穎花形態之影響。在外表性狀上，持續性表現salT基因之TNG67轉殖株，會使株高變矮，且均不結實，類似slp/slp形態；然而，在促進或抑制salT基因表現之SLP/SLP轉殖系中，植株株高及穎花形態均與非轉殖株無太大差異；因此，水稻穎花構造之變異與salT基因的關係，尚須進一步確認。在非生物逆境研究方面，誘導表現salT基因可能與水稻3-4葉齡幼苗的耐旱性有關，在耐鹽性與耐冷性方面未見特殊影響，須再經試驗確認。

The size and shape of lemma and palea may limit the developing of rice grains, that could affect the rice yield indirectly. Therefore it is interesting to clone genes related to lemma and palea. In this thesis, six genes from the lemma/palea related gene pool which is established by Liu (2003) were further studied. Those genes are salT gene (salt-induced protein), GA-SPY gene (gibberellin action negative regulator SPY-related protein), U2AF gene (U2 snRNP auxiliary factor, small subunit-related protein), kinesin-like gene, DnaJ-like gene, and EF hand gene. At first, the gene expression in leaves and 1~4 cm inflorescences of normal lemma/palea (SLP/SLP), smaller lemma/palea (SLP/slp), and stunted lemma/palea (slp/slp) was compared by Real Time RT-PCR. The results showed that salT expression is higher in leaf sheath than in leaf lamina, and is especially high in the inflorescence of slp/slp mutant. The Southern blot showed that only one copy of salT gene in rice genome. SalT gene was transferred to TNG67 and SLP/SLP rice plant by Agro-transformation method. Three kinds of constructs were designed for over expression, induced expression, and knock out expression of salT gene. The transgenic rice plants with over expressed of salT gene in TNG67 were lower and no spikelets. However, the plant height and the size of lemma/palea of SLP/SLP transgenic rice plants showed no difference to the non-transgenic rice plants. Therefore, the relationship between salT and the structure of spikelets must be studied in more details. The transgenic rice plants with over expressed salT gene showed higher drought tolerance, but no special performance under salt or cold stress.