Dwarf mutants in plants are crucial for elucidating regulatory mechanisms for plant growth and development. Previous studies suggested that the heterotrimeric G-protein alpha subunit known as D1/RGA1 in rice was involved in deactivation function of the G protein. However, so far no partner has been analyzed the spatial structure change acting with D1. In this study, a dwarf mutant designated Mu101 was obtained in M2 population of rice indica cultivar M804 treated with 60Co γ-ray. Genetic analysis of Mu101 indicated that the dwarf phenotype was controlled by a single dwarf gene, and the dwarf mutant was insensitive to gibberellin (GA), which was named dwarf 89 (d89). Using a large F2 population derived from a cross between the d89 and a japonica rice variety, Taigeng16, the D89 gene was fine mapped into a 62.13 kb physical distance on chromosome 5, where eight open reading frames were predicted. Sequence analysis indicated that only one bp substitution (A-G) was found in LOC_Os05g26890 between M804 and the d89 mutant. The rice GA insensitive dwarf mutant DWARF1 gene was in this locus. The modeling analysis showed amino acid threonine to alanine mutation was likely to make the alpha helix short, and led to the G protein deactivation.
植物矮化突變體對于闡明植物生長和發(fā)育的調(diào)控機制十分重要。之前研究表明，水稻中異源三聚體G蛋白α亞基D1/RGA1參與G蛋白的功能失活。但是，到目前為止，仍沒對D1作用時的空間結(jié)構(gòu)變化進行分析。本文研究中，從60Coγ射線處理秈稻品種M804得到的M2群體中獲得了一個矮化突變體，命名為Mu101。Mu101的遺傳分析表明，矮化表型是由單個矮化基因控制的，矮化突變體對赤霉素（GA）不敏感，因而命名dwarf 89（d89）。利用d89和粳稻品種泰粳16雜交產(chǎn)生的較大的F2群體，將D89基因精細定位到5號染色體62.13 kb的物理距離內(nèi)，包含8個預(yù)測的開放性閱讀框。序列分析表明，M804和d89突變體之間只有LOC_Os05g26890內(nèi)有一個堿基由A替換為G。水稻GA不敏感突變體DWARF1基因在這個位點內(nèi)。建模分析表明氨基酸蘇氨酸突變?yōu)楸彼釙功谅菪兌?，?dǎo)致G蛋白失活。