甘薯CIN基因家族鉴定及影响块根膨大关键CIN基因的挖掘

Identification of CIN Gene Family in Sweetpotato and Screen of Key CIN Genes Regulating Storageroot Development

细胞质转化酶(CIN)催化蔗糖不可逆地水解为葡萄糖和果糖,在模式植物根系生长发育中发挥着重要作用。目前尚未对甘薯CIN基因家族进行研究,更不清楚CIN在甘薯块根膨大中的具体作用。本研究系统鉴定了甘薯CIN基因家族的种类和数量并分析其蛋白质理化性质、染色体定位、系统发育、基因结构和保守基序、启动子顺式元件,同时,分析甘薯CIN家族基因在不同组织部位进行的表达特异性分析及其在不同类型根系中的表达水平和酶活性,初步筛选出在甘薯块根膨大中发挥重要作用的关键候选CIN基因。结果如下:(1)从甘薯(Ipomoeabatatas)基因组中共鉴定出12个IbCIN基因(IbCIN1-12),分布于8条染色体上,编码蛋白质的氨基酸数量范围为417~825 aa,分子量范围为46.60~93.75 kDa,等电点范围为4.83~7.17。(2)系统发育分析发现IbCIN可分为3个亚组,其中α1亚组1个,α2亚组3个,β亚组8个。α1、α2亚组成员之间在保守基序和基因结构上差异较小、相对保守,而β亚组成员之间则差异较大,表明β亚组的IbCIN基因可能在功能上更为多样,可以参与更多的生物过程。此外,IbCIN1、IbCIN7、IbCIN10、IbCIN12与拟南芥和木薯根系发育相关CIN基因的亲缘关系较近,推测其可能与非块根类型根系发育密切相关。(3)IbCINs在不同组织部位(幼叶、成熟叶、茎、花、60 d块根)和不同类型根系(白色纤维根、红色纤维根、柴根和60 d块根)中的表达水平分析表明,IbCIN4、IbCIN8和IbCIN11在块根中的表达水平最高,同时块根中的CIN酶活性也显著高于非块根类型根系,推测这3个基因可能在甘薯块根膨大中发挥着重要作用。(4)生物信息学分析进一步揭示IbCIN4、IbCIN8和IbCIN11可能通过调控蔗糖转运和代谢、光周期反应、赤霉素信号转导等途径和机制来共同促进甘薯块根的发育。本研究可为后续通过转基因技术等手段深入研究甘薯CIN基因的功能奠定基础。

Cytoplasmic invertase(CIN)irreversibly hydrolyzes sucrose into glucose and fructose and plays an important role in the development of roots in various model plants.Presently,there is no research on the CIN gene family in sweetpotato(Ipomoea batatas)and the role of IbCINs in the development of storage roots of sweetpotato remains to be elucidated.This study systematically identified the types and quantities of IbCIN gene family.Physicochemical properties,chromosome localization,phylogeny,gene structure and conserved motifs,promoter cis elements of IbCINs were also analyzed.Simultaneously,through the expression analysis of IbCINs in different tissues and different types of roots,and the activity analysis of CIN in different types of roots,several candidate CIN genes were identified that play an important role in the development of storage roots of sweetpotato.A total of 12 IbCIN genes(IbCIN1-12)were identified from the genome of sweetpotato,distributing on 8 chromosomes.The number of amino acids of IbCIN-encoded protein was 417‒825 aa,the molecular weightwas 46.60‒93.75 kDa,and the isoelectric point was 4.83‒7.17.Phylogenetic analysis revealed that IbCINs could be divided into three groups,α1,α2 andβgroups,comprising 1,3 and 8 members,respectively.α1 andα2 members were very conservative in conserved motifs and gene structures,whileβmemberswere less conservative,which indicating thatβgroup may have more diverse function than the other two groups,allowingβmembers to participate in more biological processes.In addition,phylogenetic analysis also revealed that IbCIN1,IbCIN7,IbCIN10 and IbCIN12 were closely related to CIN genes related to root development in Arabidopsis and cassava,suggesting that the four genes may play important roles in the development of non-storage root of sweetpotato.The analysis of the expression levels of IbCINs in different tissue(young leaves,mature leaves,stems,flowers,60 d storage roots)and different types of roots(white fiber roots,red fiber roots,pencil roots and 60 d storage roots)showed that IbCIN4,IbCIN8 and IbCIN11 had the highest expression levels in storage roots,and simultaneously the CIN activity in storage roots was significantly higher than that in non-storage roots.Thus,it can be speculated that the three genes may play an important role in the development of storage roots of sweetpotato.Bioinformatics analysis further revealed that IbCIN4,IbCIN8 and IbCIN11 may jointly promote the development of storage roots via different mechanisms,including facilitating sucrose transport to and subsequent degradation in storage roots,attenuating photoperiod response and signal transduction of gibberellin.This study could lay a foundation for further research on the function of IbCIN genes through transgenic technology.