苔藓NAC基因家族的生物信息学分析

Bioinformatics Analysis of NAC Gene Family in Bryophytes

NAC(NAM,ATAF,CUC)转录因子家族仅存在于陆生植物中,在植物发育、响应胁迫以及生物合成过程中发挥重要作用。许多NAC家族成员的功能已被确定(主要在模式植物中),但在苔藓等早期陆生植物中NAC家族的进化过程尚不清楚。本研究从藓类的小立碗藓(Physcomitrella patens)和泥炭藓(Sphagnum fallax)、苔类的地钱(Marchantia polymorpha)和角苔类的角苔(Anthoceros angustus)中,共鉴定出97个NAC基因,并对其进行NAC转录因子家族进化分析。藓类有大约40个NAC基因,地钱和角苔中只有大约10个NAC基因。在苔藓植物中,NAC基因家族可分为5个亚家族。基因结构和保守结构域分析表明,在同一个亚家族中,大多数NAC基因具有相似的基因结构和编码相似的蛋白基序。共线性分析表明NAC-Ⅱ基因位于藓类植物保守共线性区,并随着藓类植物的整个基因重复事件而扩张。上述研究结果表明NAC基因的扩张不仅发生在维管植物中,也发生在苔藓植物中,这对NAC基因家族的功能扩展是至关重要的。进一步研究结果显示,NAC基因家族的扩增时间与藓类植物的全基因组复制(whole genome duplication,WGD)事件密切相关,说明NAC基因家族伴随着全基因复制事件发生扩张。

NAC(NAM,ATAF,and CUC)transcription factor family is found only in land plants and plays important roles in development,stress responses,and biosynthesis.The functions of many NAC family members have been identified(primarily in model plants),but the evolution of the NAC family in early land plants like bryophytes is not clear.In this study,we analyzed the evolution of the NAC gene family using 97 NAC genes in four bryophyte genomes(the mosses Physcomitrella patens and Sphagnum fallax,the liverwort Marchantia polymorpha,and the hornwort Anthoceros angustus).Mosses have about 40 NAC genes and liverworts and hornworts have only about 10 NAC genes.In bryophytes,the NAC family is divided into five subfamilies.Analysis of gene structure and conserved domains showed that most NAC genes in the same subfamily had similar gene structures and encode similar protein motifs.Collinear analysis showed that the NAC-Ⅱ gene was located at the conserved collinear region of mosses and expanded with the entire gene repeat event in mosses.These results indicate that the expansion of NAC gene occurs not only in vascular plants but also in bryophytes,which is crucial for functional extension of the NAC gene family.Further studies showed that the amplification of the NAC gene family is closely related to the whole genome duplication(WGD)event in mosses,suggesting that the expansion time of the NAC gene family is accompanied by the whole gene duplication event.