College of Life Science and Technology, Gansu Agricultural University, Lanzhou, 730070, China.
Gansu Provincial Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou, 730070, China.
BMC Genomics. 2024 Mar 28;25(1):316. doi: 10.1186/s12864-024-10095-7.
Alfalfa is a perennial forage crop of high importance, but its cultivation is often affected by drought stress. Currently, the investigation of drought-related small RNAs is a popular research topic to uncover plant drought resistance mechanisms. Among these small RNAs, microRNA166 (miR166) is associated with drought in numerous plant species. Initial small RNA sequencing studies have shown that miR166 is highly responsive to exogenous nitric oxide (NO) and drought. Therefore, analyzing the expression of Msa-miR166 under nitric oxide and drought treatment is significant.
Bioinformatics analysis revealed that the miR166 family is widely distributed among plants, ranging from mosses to eudicots, with significant distribution differences between species. The evolutionary degree of Msa-miR166s is highly similar to that of Barrel medic (Medicago truncatula) and Soybean (Glycine max), but significantly different from the model plant Arabidopsis (Arabidopsis thaliana). It is suggested that there are no significant differences in miR166s within the species, and members of Msa-miR166s can form a typical stem-loop. The lowest level of exogenous nitric oxide was observed in Msa-miR166s under drought stress, followed by individual drought, and the highest level was observed after removing endogenous nitric oxide.
In response to short-term drought, Msa-miR166s down-regulate expression in alfalfa (Medicago sativa L.). Exogenous nitric oxide can reduce the expression of Msa-miR166s in response to short-term drought. These findings suggest that Msa-miR166e-5p is responsive to environmental changes. The expression levels of target genes showed an opposite trend to Msa-miR166s, verifying the accuracy of Degradome sequencing in the early stage. This suggests that alfalfa experiences drought stress when regulated by exogenous nitric oxide, targeting HD ZIP-III, FRI, and CoA ligase genes. Additionally, the expression of Msa-miR166s in response to drought stress varies between leaves and roots, indicating spatiotemporal specificity.
紫花苜蓿是一种非常重要的多年生饲料作物，但它的种植常常受到干旱胁迫的影响。目前，研究与干旱相关的小 RNA 是揭示植物抗旱机制的热门研究课题。在这些小 RNA 中，miR166 与许多植物物种的干旱有关。最初的小 RNA 测序研究表明，miR166 对外源一氧化氮（NO）和干旱高度响应。因此，分析一氧化氮和干旱处理下 Msa-miR166 的表达情况具有重要意义。
生物信息学分析表明，miR166 家族广泛分布于植物中，从苔藓到真双子叶植物，不同物种之间的分布差异显著。Msa-miR166s 的进化程度与 Barrel medic（Medicago truncatula）和大豆（Glycine max）非常相似，但与模式植物拟南芥（Arabidopsis thaliana）有显著差异。这表明物种内的 miR166s 没有显著差异，Msa-miR166s 的成员可以形成典型的茎环结构。在干旱胁迫下，Msa-miR166s 的外源一氧化氮水平最低，其次是单独的干旱处理，而内源一氧化氮去除后的水平最高。
在短期干旱胁迫下，Msa-miR166s 在紫花苜蓿（Medicago sativa L.）中下调表达。外源一氧化氮可以降低 Msa-miR166s 对短期干旱的表达。这些发现表明 Msa-miR166e-5p 对环境变化有响应。靶基因的表达水平与 Msa-miR166s 呈相反趋势，早期降解组测序的准确性得到验证。这表明，当受到外源一氧化氮的调节时，紫花苜蓿会经历干旱胁迫，针对 HD ZIP-III、FRI 和 CoA 连接酶基因。此外，Msa-miR166s 对干旱胁迫的响应在叶片和根之间存在差异，表现出时空特异性。
