水稻OsUBA基因的表达及其在促进种子萌发和开花中的功能

Expression of OsUBA and its function in promoting seed germination and flowering

自噬是将功能异常或不需要的胞内组分降解的细胞学过程,广泛参与真核生物的生长发育过程、对营养缺乏的响应及生物/非生物胁迫反应。NBR1 (Next to BRCA1 gene 1,NBR1)是在植物中发现的最重要的自噬受体,但有关植物NBR1类自噬受体的研究较少,水稻中此类蛋白的研究还是空白。本文通过RT-PCR方法,从水稻日本晴幼苗的cDNA中克隆到一个含有泛素相关结构域(Ubiquitin associated,UBA)的基因,将其命名为OsUBA。OsUBA的开放阅读框长2538bp,编码845个氨基酸残基。OsUBA属于水稻中的NBR1类蛋白。OsUBA的启动子区有多个与光、逆境胁迫及激素反应相关的元件;OsUBA基因在水稻花药、正在萌发的种子以及根中的表达量较高,在茎和叶中也有表达;200μmol L^–1 ABA处理显著抑制OsUBA的表达,100 μmol L^–1 GA处理后OsUBA的表达略有升高。对OsUBA过表达水稻株系的研究表明,转基因水稻种子的萌发比野生型更快,ABA(3 μmol L^–1)处理显著抑制OsUBA过表达水稻株系种子的萌发,GA(100 μmol L^–1)处理对OsUBA过表达水稻株系种子的萌发略有促进;OsUBA过表达水稻株系的开花时间较野生型明显提前。这些结果表明,水稻NBR1蛋白基因OsUBA的表达和功能可能与对开花时间和种子萌发的调控以及生物/非生物胁迫反应有关。

Autophagy is a cellular process by which dysfunctional or unnecessary cellular components are degraded.Autophagy plays important roles in growth and development,and makes responses to nutritional deficiency and biotic/abiotic stress responsiveness in eukaryotes.NBR1 (Next to BRCA1 gene 1,NBR1) proteins were the most important autophagy cargo receptors found in plants.Up to date,only limited reports about NBR1 were available in plants,and the function of NBR1 proteins in rice remains unclear.An UBA (Ubiquitin associated,UBA) domain-containing gene was cloned from cDNA of rice (Oryza sativa L.japonica cv.Nipponbare) seedlings and was named as OsUBA.The open reading frame of OsUBA is 2538 bp in length and encodes 845 amino acids residues.Conserved domain prediction and phylogenetic analysis suggested that OsUBA belongs to NBR1 proteins.Promoter analysis suggested that many motifs related to light-,stress-,and hormone responsiveness were predicted in OsUBA promoter sequence.Gus staining of the rice plants harboring OsUBA p:Gus showed that OsUBA was highly expressed in anthers,germinating seeds,and roots,OsUBA transcripts could also be detected in stems and leaves.Expression of OsUBA was dramatically inhibited by 200 μmol L^–1 ABA treatment,and slightly increased by 100 μmol L^–1 GA treatment.Compared with the wild type control,the OsUBA-overexpressors germinated more quickly and flowered obviously earlier.The seed germination of the OsUBA-overexpressed rice lines was obviously inhibited by 3 μmol L^–1 ABA treatment,and promoted slightly by 100 μmol L^–1 GA treatment.These results suggested that the expression and function of OsUBA may be related to regulations of flowering time,seed germination and biotic/abiotic stress responsiveness in rice.