谷子转录因子基因SiNAC45在拟南芥中对低钾及ABA的响应

摘要

NAC (nascent polypeptide-associated complex) like transcription factors play important role in plant growth and de-velopment, abiotic stress response, and other processes. Currently, few researches reported NAC like transcription factors involv-ing in tolerance to low potassium stress. In this study, we found and researched a NAC like transcription factor gene SiNAC45 on the basis of transcriptome sequence of millet under low potassium stress which had been completed in previous work. The result show that the full-length ofSiNAC45 is 1383 bp, encoding 461 amino acids, with molecular weight and isoelectric point of 50.7 kD and 6.92, respectively. There is a conserved NAM domain between 20–100 amino acids of SiNAC45. The phylogenetic tree showed that SiNAC45 belonged to the first subfamily of NAC gene family. The gene expression profile results indicatedSiNAC45 mainly expressed in roots and was induced by ABA and low potassium treatment. The protein subcellular localization results of SiNAC45 revealed that it was localized in the nucleus. Gene functional analysis showed that under treatment with different con-centrations of potassium, root length and fresh weightofSiNAC45 transgenicArabidopsis significantly increased compared with those of wild-typeArabidopsis, and there was no significant difference in the number of lateral roots between transgenic and wild-typeArabidopsis, indicating that overexpressing ofSiNAC45 in transgenic plants can enhance tolerance to low potassium stress. Expression analysis of downstream gene showed that expression of two important potassium transporter genesAKT1 and HAK1 increased significantly inSiNAC45 transgenic plants, indicating thatSiNAC45 affects the tolerance to low potassium stress of plants by regulating the expression of potassium transporter gene. Seed germination test results showed thatArabidopsis carry-ingSiNAC45 decreased the sensitivity to ABAcompared with wild-typeArabidopsis, indicating thatSiNAC45 maybe negatively regulate ABA signal pathway.%NAC (nascent polypeptide-associated complex)转录因子在植物生长发育和非生物胁迫响应等过程中发挥重要的调控作用,目前,关于 NAC 转录因子参与耐低钾胁迫的研究报道很少。本研究在前期工作对低钾胁迫的转录组测序基础上,对筛选出的一个低钾胁迫下表达量上调的 NAC 类转录因子基因 SiNAC45进行了深入研究。结果表明, SiNAC45基因全长1383 bp,编码461个氨基酸,分子量为50.7 kD,等电点为6.92。SiNAC45在20~100个氨基酸之间有一段NAM保守结构域。系统进化树结果显示, SiNAC45位于NAC基因家族的第1亚族。基因表达谱分析显示, SiNAC45主要在谷子根部表达,并且能够被低钾和ABA诱导表达。亚细胞定位结果显示SiNAC45定位于细胞核。基因功能分析结果显示,在不同浓度低钾处理下,和野生型拟南芥相比, SiNAC45转基因拟南芥的根长和植株鲜重显著增加,说明过表达SiNAC45可以提高转基因植物对低钾胁迫的抗性。下游基因表达分析结果显示,在 SiNAC45转基因植物中两种重要的钾离子转运体基因AKT1和HAK1的表达显著提高,证明SiNAC45通过调控植物钾离子转运体基因的表达影响植物对低钾胁迫的耐性。种子萌发试验结果显示, SiNAC45转基因拟南芥与野生型拟南芥相比对 ABA 的敏感性降低,说明SiNAC45可能负调ABA信号。