花生 NAC 转录因子家族的全基因组特征及其对盐和干旱胁迫的响应

BACKGROUND

Peanut is one of the most important oil crop species worldwide. NAC transcription factor (TF) genes play important roles in the salt and drought stress responses of plants by activating or repressing target gene expression. However, little is known about NAC genes in peanut.

RESULTS

We performed a genome-wide characterization of NAC genes from the diploid wild peanut species Arachis duranensis and Arachis ipaensis, which included analyses of chromosomal locations, gene structures, conserved motifs, expression patterns, and cis-acting elements within their promoter regions. In total, 81 and 79 NAC genes were identified from A. duranensis and A. ipaensis genomes. Phylogenetic analysis of peanut NACs along with their Arabidopsis and rice counterparts categorized these proteins into 18 distinct subgroups. Fifty-one orthologous gene pairs were identified, and 46 orthologues were found to be highly syntenic on the chromosomes of both A. duranensis and A. ipaensis. Comparative RNA sequencing (RNA-seq)-based analysis revealed that the expression of 43 NAC genes was up- or downregulated under salt stress and under drought stress. Among these genes, the expression of 17 genes in cultivated peanut (Arachis hypogaea) was up- or downregulated under both stresses. Moreover, quantitative reverse transcription PCR (RT-qPCR)-based analysis revealed that the expression of most of the randomly selected NAC genes tended to be consistent with the comparative RNA-seq results.

CONCLUSION

Our results facilitated the functional characterization of peanut NAC genes, and the genes involved in salt and drought stress responses identified in this study could be potential genes for peanut improvement.

背景

花生是全球最重要的油料作物之一。NAC 转录因子（TF）基因通过激活或抑制靶基因的表达，在植物的盐和干旱胁迫响应中发挥重要作用。然而，关于花生中的 NAC 基因知之甚少。

结果

我们对二倍体野生花生种 Arachis duranensis 和 Arachis ipaensis 中的 NAC 基因进行了全基因组特征分析，包括对染色体位置、基因结构、保守基序、表达模式以及启动子区域内顺式作用元件的分析。总共从 A. duranensis 和 A. ipaensis 基因组中鉴定出 81 个和 79 个 NAC 基因。对花生 NAC 及其拟南芥和水稻对应物的系统发育分析将这些蛋白分为 18 个不同的亚群。鉴定出 51 个直系同源基因对，并且在 A. duranensis 和 A. ipaensis 的染色体上发现了 46 个直系同源物高度同源。基于比较 RNA 测序（RNA-seq）的分析表明，在盐胁迫和干旱胁迫下，43 个 NAC 基因的表达上调或下调。在这些基因中，栽培花生（Arachis hypogaea）中 17 个基因的表达在两种胁迫下均上调或下调。此外，基于定量逆转录 PCR（RT-qPCR）的分析表明，大多数随机选择的 NAC 基因的表达与比较 RNA-seq 结果趋于一致。