Jain Mukesh, Tyagi Akhilesh K, Khurana Jitendra P
Interdisciplinary Centre for Plant Genomics and Department of Plant Molecular Biology, University of Delhi South Campus, Benito Juarez Road, New Delhi 110 021, India.
Genomics. 2006 Sep;88(3):360-71. doi: 10.1016/j.ygeno.2006.04.008. Epub 2006 May 16.
Small auxin-up RNAs (SAURs) are the early auxin-responsive genes represented by a large multigene family in plants. Here, we report the identification of 58 OsSAUR gene family members from rice (Oryza sativa japonica cv Nipponbare), the model monocot plant, by a reiterative database search and manual reannotation; 2 of these are pseudogenes. The coding sequences of OsSAURs do not possess any intron. Most of the predicted OsSAUR protein sequences harbor a putative nuclear localization signal at their N-terminus. Localized gene duplications appear to be the primary genetic event responsible for SAUR gene family expansion in rice. Interestingly, the duplication of OsSAURs was found to be associated with the chromosomal block duplication as well. The phylogenetic analysis revealed that the SAUR gene family expanded in rice and Arabidopsis due to species-specific expansion of the family in monocots and dicots. The auxin-responsive elements and downstream element are conserved in the upstream and downstream sequences, respectively, of OsSAURs. In addition to the 21 OsSAURs with full-length cDNA sequences and 20 with expressed sequence tags, gene expression analyses of at least 7 OsSAURs by RT-qPCR indicated that the majority of identified OsSAURs most likely are expressed in rice. The transcript abundance of the OsSAURs examined increased within a few minutes of exogenous auxin application with varying kinetics. The present study provides basic genomic information for the rice SAUR gene family and will pave the way for deciphering the precise role of SAURs in plant growth and development.
小生长素上调RNA（SAURs）是植物中由一个大型多基因家族所代表的早期生长素响应基因。在此，我们通过反复的数据库搜索和人工重新注释，从模式单子叶植物水稻（粳稻品种日本晴）中鉴定出58个OsSAUR基因家族成员；其中2个为假基因。OsSAURs的编码序列不含有任何内含子。大多数预测的OsSAUR蛋白序列在其N端含有一个假定的核定位信号。局部基因重复似乎是水稻中SAUR基因家族扩张的主要遗传事件。有趣的是，还发现OsSAURs的重复与染色体区段重复有关。系统发育分析表明，SAUR基因家族在水稻和拟南芥中扩张是由于该家族在单子叶植物和双子叶植物中的物种特异性扩张。生长素响应元件和下游元件分别在OsSAURs的上游和下游序列中保守。除了21个具有全长cDNA序列的OsSAURs和20个具有表达序列标签的OsSAURs外，通过RT-qPCR对至少7个OsSAURs进行的基因表达分析表明，大多数已鉴定的OsSAURs很可能在水稻中表达。所检测的OsSAURs的转录本丰度在施加外源生长素后的几分钟内以不同的动力学增加。本研究为水稻SAUR基因家族提供了基本的基因组信息，并将为阐明SAURs在植物生长发育中的精确作用铺平道路。
