Fructosyltransferase and invertase genes evolved by gene duplication and rearrangements: rice, perennial ryegrass, and wheat gene families.

The invertase enzyme family is responsible for carbohydrate metabolism in rice, perennial ryegrass, and wheat. Fructan molecules accumulate in cell vacuoles of perennial ryegrass and wheat and are associated with abiotic stress tolerance. High levels of amino acid similarity between the fructosyltransferases responsible for fructan accumulation indicates that they may have evolved from invertase-like ancestral genes. In this study, we have applied comparative genomics to determine the mechanisms that lead to the evolution of fructosytransferase and invertase genes in rice, perennial ryegrass, and wheat. Duplications and rearrangements have been inferred to generate variant forms of the rice invertases since divergence from a common grass progenitor. The occurrence of multiple copies of fructosyltransferase genes indicated that duplication events continued during evolution of the wheat and perennial ryegrass lineages. Further gene rearrangements were evident in perennial ryegrass genes, albeit at a reduced level compared with the rice invertases. Gene orthologs were largely static after duplication during evolution of the wheat lineage. This study details evolutionary events that contribute to fructosyltransferase and invertase gene variation in grasses.     

互花米草NAC转录因子家族的鉴定与表达分析

互花米草(Spartina alterniflora)作为一种海岸带盐生植物,高度耐盐胁迫,但因为缺少参考基因组,其耐盐的分子机制却尚未见报道。NAC家族蛋白是植物特有的转录因子,调控植物的生长发育和胁迫应答。为了鉴定互花米草NAC蛋白(SaNAC)并探究它们与互花米草生长发育及胁迫响应之间的关系,本研究以互花米草三代全长转录组数据为参考,通过与水稻(Oryza sativa)、拟南芥(Arabidopsis thaliana)和玉米(Zea mays)NAC蛋白序列进行比对,并结合保守功能域进一步筛选,最终找到62个SaNAC蛋白。从蛋白序列比对、进化、motif预测、同源性比较、亚细胞定位、组织表达以及非生物胁迫下的基因差异表达等方面分别对互花米草NAC家族成员进行分析,结果发现SaNAC蛋白均含有保守的NAM结构域,且在进化上与水稻NAC家族具有一定的相似性;SaNAC家族中的两个蛋白SaNAC9和SaNAC49在细胞核表达;另外,本研究还发现互花米草SaNAC基因表达具有高度组织和胁迫应答差异性。这些结果表明互花米草NAC转录因子家族不仅具有保守的功能域,而且在调控互花米草的生长发育和非生物胁迫响应过程中具有重要的作用。     

非生物胁迫相关NAC转录因子的结构及功能

NAC是植物特有的一类转录因子,参与植物多个生长发育过程,还参与植物对逆境胁迫的响应。本文对非生物胁迫相关NAC转录因子的结构特征、功能预测、表达特性、在转基因植物中的作用及调控路径进行综述。非生物胁迫相关NAC转录因子具有典型的NAc胁迫亚家族结构特征,根据这些结构特征可以预测其功能;非生物胁迫相关NAc转录因子能响应多种非生物胁迫,其转基因过表达大多能使转基因植物提高一种或几种胁迫耐受性;非生物胁迫相关NAc转录因子有着复杂的调控路径。这些NAc转录因子可用于提高转基因植物的逆境耐受性。     

苦荞NAC转录因子FtNAC17的鉴定及表达分析

植物特有的NAC转录因子参与植物生长发育和逆境响应。研究苦荞中NAC转录因子在非生物胁迫中的应答,为阐明基因功能提供理论依据。以苦荞为试验材料,克隆一个NAC家族基因,对其进行生物信息学分析。通过荧光定量PCR技术检测该基因在干旱、低温、盐、茉莉酸甲酯、脱落酸和赤霉素胁迫时的响应情况。该基因编码272个氨基酸,将其命名为FtNAC17,GenBank登录号为MT641452。基因结构分析表明,FtNAC17由2个外显子和1个内含子组成。氨基酸序列多重比对和进化关系分析表明,FtNAC17蛋白与拟南芥ANAC002亲缘关系最近,属于NAC转录因子家族中同一亚组。FtNAC17对干旱、低温、盐等非生物胁迫均有不同程度的响应。