Dong Xiu-Mei, Pu Xiao-Jun, Zhou Shi-Zhao, Li Ping, Luo Ting, Chen Ze-Xi, Chen Si-Lin, Liu Li
Key Laboratory Dependent on for Economic Plants and Biotechnology, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China.
Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China Ministry of Education, Southwest Forestry University, Kunming, 650201, China.
Plant Sci. 2022 Jun;319:111222. doi: 10.1016/j.plantsci.2022.111222. Epub 2022 Mar 14.
Almost all genomes have orphan genes, the majority of which are not functionally annotated. There is growing evidence showed that orphan genes may play important roles in the environmental stress response of Physcomitrium patens. We identified PpARDT (ABA-responsive drought tolerance) as a moss-specific and ABA-responsive orphan gene in P. patens. PpARDT is mainly expressed during the gametophytic stage of the life cycle, and the expression was induced by different abiotic stresses. A PpARDT knockout (Ppardt) mutant showed reduced dehydration-rehydration tolerance, and the phenotype could be rescued by exogenous ABA. Meanwhile, transgenic Arabidopsis lines exhibiting heterologous expression of PpARDT were more sensitive to exogenous ABA than wild-type (Col-0) plants and showed enhanced drought tolerance. These indicate that PpARDT confers drought tolerance among land plants potentially by enhancing ABA response. Further, we identified genes encoding abscisic acid receptor PYR/PYL family proteins, and ADP-ribosylation factors (Arf) as hub genes associated with the Ppardt phenotype. Given the lineage-specific characteristics of PpARDT, our results provide insights into the roles of orphan gene in shaping lineage-specific adaptation possibly by recruiting common pre-existed pathway components.
几乎所有的基因组都有孤儿基因，其中大多数没有功能注释。越来越多的证据表明，孤儿基因可能在小立碗藓的环境应激反应中发挥重要作用。我们将PpARDT（脱落酸响应型耐旱基因）鉴定为小立碗藓中一个苔藓特异性且对脱落酸有响应的孤儿基因。PpARDT主要在生命周期的配子体阶段表达，并且其表达受不同非生物胁迫诱导。PpARDT基因敲除（Ppardt）突变体表现出脱水-复水耐受性降低，且该表型可通过外源脱落酸挽救。同时，表现出PpARDT异源表达的转基因拟南芥株系对外源脱落酸比野生型（Col-0）植株更敏感，并表现出增强的耐旱性。这些表明PpARDT可能通过增强脱落酸响应赋予陆地植物耐旱性。此外，我们鉴定出编码脱落酸受体PYR/PYL家族蛋白的基因以及ADP核糖基化因子（Arf）作为与Ppardt表型相关的枢纽基因。鉴于PpARDT的谱系特异性特征，我们的结果为孤儿基因可能通过招募常见的预先存在的途径成分来塑造谱系特异性适应性的作用提供了见解。
