Upland Flue-cured Tobacco Quality and Ecology Key Laboratory, Guizhou Academy of Tobacco Science, Guiyang, P. R. China.
College of Tobacco Science, Guizhou University, Guiyang, P. R. China.
Physiol Plant. 2024 Jul-Aug;176(4):e14436. doi: 10.1111/ppl.14436.
Small secreted peptides (SSPs), serving as signaling molecules for intercellular communication, play significant regulatory roles in plant growth, development, pathogen immunity, and responses to abiotic stress. Despite several SSPs, such as PIP, PSK, and PSY having been identified to participate in plant immunity, the majority of SSPs remain understudied, necessitating the exploration and identification of SSPs regulating plant immunity from vast genomic resources. Here we systematically characterized 756 putative SSPs across the genome of Nicotiana tabacum. 173 SSPs were further annotated as established SSPs, such as nsLTP, CAPE, and CEP. Furthermore, we detected the expression of 484 putative SSP genes in five tissues, with 83 SSPs displaying tissue-specific expression. Transcriptomic analysis of tobacco roots under plant defense hormones revealed that 46 SSPs exhibited specific responsiveness to salicylic acid (SA), and such response was antagonistically regulated by methyl jasmonate. It's worth noting that among these 46 SSPs, 16 members belong to nsLTP family, and one of them, NtLTP25, was discovered to enhance tobacco's resistance against Phytophthora nicotianae. Overexpression of NtLTP25 in tobacco enhanced the expression of ICS1, subsequently stimulating the biosynthesis of SA and the expression of NPR1 and pathogenesis-related genes. Concurrently, NtLTP25 overexpression activated genes associated with ROS scavenging, consequently mitigating the accumulation of ROS during the subsequent phases of pathogenesis. These discoveries indicate that these 46 SSPs, especially the 16 nsLTPs, might have a vital role in governing plant immunity that relies on SA signaling. This offers a valuable source for pinpointing SSPs involved in regulating plant immunity.
小分泌肽（SSPs）作为细胞间通讯的信号分子，在植物生长、发育、病原体免疫以及对非生物胁迫的响应中发挥着重要的调节作用。尽管已经鉴定出一些 SSPs，如 PIP、PSK 和 PSY，参与了植物免疫，但大多数 SSPs 仍未得到充分研究，因此需要从大量基因组资源中探索和鉴定调节植物免疫的 SSPs。在这里，我们系统地研究了烟草基因组中 756 个假定的 SSPs。进一步注释了 173 个 SSPs 为已建立的 SSPs，如 nsLTP、CAPE 和 CEP。此外，我们检测了 484 个假定 SSP 基因在五个组织中的表达情况，其中 83 个 SSPs 表现出组织特异性表达。对烟草根在植物防御激素下的转录组分析表明，46 个 SSPs 对水杨酸（SA）表现出特异性响应，这种响应受到茉莉酸甲酯的拮抗调节。值得注意的是，在这 46 个 SSPs 中，有 16 个成员属于 nsLTP 家族，其中一个成员 NtLTP25 被发现增强了烟草对烟草疫霉的抗性。在烟草中过表达 NtLTP25 增强了 ICS1 的表达，进而刺激了 SA 的生物合成以及 NPR1 和病程相关基因的表达。同时，NtLTP25 的过表达激活了与 ROS 清除相关的基因，从而减轻了病程后期 ROS 的积累。这些发现表明，这 46 个 SSPs，特别是 16 个 nsLTPs，可能在依赖于 SA 信号的植物免疫调控中发挥重要作用。这为鉴定参与调节植物免疫的 SSPs 提供了有价值的资源。
