State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Wenjiang 611130, Sichuan, China.
Maize Research Institute, Sichuan Agricultural University, Wenjiang 611130, Sichuan, China.
J Exp Bot. 2021 Mar 29;72(7):2790-2806. doi: 10.1093/jxb/erab023.
Although plant-specific NAC transcription factors play crucial roles in response to abiotic stress, few reports describe the regulation of NAC genes in maize (Zea mays) by the cis-natural antisense transcripts (cis-NATs). In this study, 521 NAC genes from Gramineae were classified, of which 51 NAC genes contained cis-NATs. ZmNAC48 and cis-NATZmNAC48 co-localized to the same cell nucleus, and both transcripts responded to drought stress. Arabidopsis plants overexpressing ZmNAC48 had improved drought tolerance, lower rate of water loss, enhanced stomatal closure, and higher rates of survival. Transient expression in both maize protoplasts and tobacco leaves indicated that cis-NATZmNAC48 reduced ZmNAC48 expression. Western blotting and ribosome profiling analyses confirmed that cis-NATZmNAC48 lacked protein coding potential. Furthermore, the cis-NAT-derived small-interfering RNAs (nat-siRNAs) generated from the overlapping regions of ZmNAC48 and cis-NATZmNAC48 were detected in maize and transgenic Arabidopsis. Cis-NATZmNAC48 overexpressing maize showed higher water loss rate, increased stomatal opening, and had more dead leaves. Expression of ZmNAC48 and nat-siRNA was decreased in these plants. Taken together, our study indicates that both ZmNAC48 and cis-NATZmNAC48 are involved in plant drought stress responses, and that the double-stranded RNA-dependent mechanism is involved in the interaction between cis-NATZmNAC48 and ZmNAC48. Additionally, cis-NATZmNAC48 may negatively regulate ZmNAC48 to affect stomatal closure of maize.
尽管植物特异性 NAC 转录因子在应对非生物胁迫方面发挥着关键作用，但很少有报道描述玉米（Zea mays）中 NAC 基因受顺式自然反义转录本（cis-NAT）的调控。本研究对禾本科的 521 个 NAC 基因进行了分类，其中 51 个 NAC 基因含有 cis-NAT。ZmNAC48 和 cis-NATZmNAC48 共定位于同一细胞核内，且两者的转录本均对干旱胁迫有响应。过表达 ZmNAC48 的拟南芥植株耐旱性提高，失水率降低，气孔关闭增强，存活率提高。在玉米原生质体和烟草叶片中的瞬时表达表明 cis-NATZmNAC48 降低了 ZmNAC48 的表达。Western blotting 和核糖体谱分析证实 cis-NATZmNAC48 缺乏蛋白编码能力。此外，在玉米和转基因拟南芥中检测到来自 ZmNAC48 和 cis-NATZmNAC48 重叠区的 cis-NAT 衍生的小干扰 RNA（nat-siRNA）。过表达 cis-NATZmNAC48 的玉米表现出更高的失水率、增加的气孔开度和更多的死叶。这些植物中 ZmNAC48 和 nat-siRNA 的表达降低。综上所述，本研究表明 ZmNAC48 和 cis-NATZmNAC48 均参与植物干旱胁迫响应，双链 RNA 依赖性机制参与 cis-NATZmNAC48 与 ZmNAC48 之间的相互作用。此外，cis-NATZmNAC48 可能通过负调控 ZmNAC48 来影响玉米的气孔关闭。
