Cai Mengxian, Sun Chunxing, Ou Jing, Zeng Tuo
College of Forestry, Guizhou University, Guiyang, 550025, China.
Guizhou Key Laboratory of Forest Cultivation in Plateau Mountain, School of Life Sciences, Guizhou Normal University, Guiyang, 550025, China.
BMC Plant Biol. 2025 Jul 17;25(1):924. doi: 10.1186/s12870-025-06965-1.
The NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs), which play a vital role in plant growth and development, stress response, and disease resistance, have been extensively analyzed in various plant species. However, there is limited knowledge regarding the NAC family in Rhododendron delavayi, an important ornamental flower.
In this study, a total of 102 RdNAC genes were identified from the R. delavayi genome. Phylogenetic analysis divided these genes into seven subfamilies, each characterized by similar conserved motifs. Chromosomal mapping revealed an uneven distribution of RdNACs across all 13 chromosomes, with gene family expansion driven primarily by dispersed duplication (110 gene pairs) and, to a lesser extent, tandem duplication (17 pairs). Intraspecific synteny analysis detected 26 pairs of duplicated RdNAC genes, while interspecific collinearity with Arabidopsis thaliana uncovered 83 orthologous pairs, indicating both lineage-specific diversification and conserved evolutionary relationships. Ka/Ks ratio calculations for both intra-RdNAC duplicates and RdNAC-AtNAC orthologs yielded values below 0.5, reflecting strong purifying selection. Conserved-motif and domain analyses identified ten distinct motifs and 35 structural domains, with the NAM and MIT CorA-like superfamily domains being the most prevalent. Promoter analysis of 2 kb upstream regions revealed a high abundance of abiotic stress-related cis-acting elements (e.g., ABRE, ARE, CGTCA-motif, LTR). Finally, qRT-PCR demonstrated that under drought (20% PEG) and salt (200 mM NaCl) treatments, multiple RdNACs, particularly RdNAC022 and RdNAC099, were significantly upregulated, underscoring their potential roles in stress response.
This study provides a comprehensive identification of the RdNAC TF family in R. delavayi, contributing to a better understanding of these transcription factors in this species. The findings also serve as a reference for analyzing stress responses, particularly concerning drought and salt stress in R. delavayi.
NAC（NAM、ATAF1/2和CUC2）转录因子在植物生长发育、胁迫响应和抗病性中起着至关重要的作用，已在多种植物物种中得到广泛分析。然而，对于重要观赏花卉滇杜鹃中的NAC家族，人们了解有限。
在本研究中，从滇杜鹃基因组中总共鉴定出102个RdNAC基因。系统发育分析将这些基因分为七个亚家族，每个亚家族具有相似的保守基序。染色体定位显示RdNACs在所有13条染色体上分布不均，基因家族的扩张主要由分散重复（110个基因对）驱动，其次是串联重复（17对）。种内共线性分析检测到26对重复的RdNAC基因，而与拟南芥的种间共线性分析发现83对直系同源基因对，这表明既有谱系特异性的多样化，也有保守的进化关系。对RdNAC内部重复序列和RdNAC-AtNAC直系同源序列的Ka/Ks比值计算得出的值均低于0.5，反映出强烈的纯化选择。保守基序和结构域分析确定了10个不同的基序和35个结构域，其中NAM和MIT CorA样超家族结构域最为常见。对上游2 kb区域的启动子分析揭示了大量与非生物胁迫相关的顺式作用元件（如ABRE、ARE、CGTCA-motif、LTR）。最后，qRT-PCR表明，在干旱（20% PEG）和盐（200 mM NaCl）处理下，多个RdNACs，特别是RdNAC022和RdNAC099显著上调，突出了它们在胁迫响应中的潜在作用。
本研究全面鉴定了滇杜鹃中的RdNAC转录因子家族，有助于更好地理解该物种中的这些转录因子。这些发现也为分析胁迫响应提供了参考，特别是关于滇杜鹃的干旱和盐胁迫。
