基于鹅掌楸[Liriodendron chinense (Hemsl.) Sarg.]转录组信息,对北美鹅掌楸(L. tulipifera Linn.) NAC(NAM、ATAF1 / 2 及CUC2)家族基因的结构和功能进行研究。采用RACE 技术从北美鹅掌楸叶片中克隆出16 个LtNAC 基因的开放阅读框(ORF),编号为LtNAC01 至LtNAC16。16 个LtNAC 基因的ORF 长度为561 ~1 830 bp,编码187 ~610 个氨基酸。根据理论等电点(pI),在LtNAC 基因编码的16 个LtNAC 蛋白中,9 个为碱性蛋白质,7 个为酸性蛋白质。根据蛋白质疏水性(GRAVY),16 个LtNAC 蛋白中,13 个为亲水蛋白质,3 个为两性蛋白质。蛋白质二级结构预测结果显示:16 个LtNAC 蛋白均以无规则卷曲为主要构成元件,α螺旋、延伸链和β转角则散布于整个蛋白质中。系统进化分析结果表明:北美鹅掌楸16 个LtNAC 基因可能并不参与细胞壁的生物合成,其中, LtNAC02、LtNAC03 和LtNAC04 基因可能参与北美鹅掌楸的胁迫响应。LtNAC03、LtNAC07、LtNAC08、LtNAC09、LtNAC11、LtNAC12、LtNAC14、LtNAC15 和LtNAC16 基因的相对表达量与北美鹅掌楸叶片衰老程度呈现相关性,推测该9 个LtNAC 基因可能参与调控叶片衰老。

Based on the transcriptome data of Liriodendron chinense ( Hemsl.) Sarg., structure and function of NAC (NAM, ATAF1 / 2 and CUC2) family genes from L. tulipifera Linn. were researched. Open reading frame. (ORF) of 16 LtNAC genes was cloned from leaf of L. tulipifera by RACE technology with Nos. from LtNAC01 to LtNAC16. Length of ORF of 16 LtNAC genes is 561-1 830 bp, and 187-610 amino acids are encoded. According to theoretical isoelectric point (pI), there are 9 basic proteins and 7 acidic proteins in 16 LtNAC proteins encoded by LtNAC genes. According to grand average of hydropathicity (GRAVY), there are 13 hydrophilic proteins and 3 hydrophonic proteins in 16 LtNAC proteins. The predicting result of secondary structure of LtNAC protein shows that random coil is main component in all of 16 LtNAC proteins, and αhelix, extended strand and βturn distribute widely in the whole protein. The result of phylogenetic analysis shows that 16 LtNAC genes of L. tulipifera may not participate in cell wall biosynthesis, in which, LtNAC02, LtNAC03 and LtNAC04 genes may participate in stress response of L. tulipifera. Relative expression of LtNAC03, LtNAC07, LtNAC08, LtNAC09, LtNAC11, LtNAC12, LtNAC14, LtNAC15 and LtNAC16 genes is related to leaf senescence progression of L. tulipifera, and it is predicted that the nine LtNAC genes may participate in regulating leaf senescence progression.