Pan Jiao, Wang Yaohai, Li Chao, Zhang Simo, Ye Zhiqiang, Ni Jiahao, Li Haichao, Li Yichen, Yue Hongwei, Ruan Chenchen, Zhao Dange, Jiang Yujian, Wu Xiaolin, Shen Xiaopeng, Zufall Rebecca A, Zhang Yu, Li Weiyi, Lynch Michael, Long Hongan
Key Laboratory of Evolution and Marine Biodiversity (Ministry of Education), Institute of Evolution and Marine Biodiversity, Ocean University of China, Qingdao, Shandong 266003, China.
Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, Shandong 266237, China.
ISME J. 2024 Jan 8;18(1). doi: 10.1093/ismejo/wrae136.
Phenotypic plasticity, which involves phenotypic transformation in the absence of genetic change, may serve as a strategy for organisms to survive in complex and highly fluctuating environments. However, its reaction norm, molecular basis, and evolution remain unclear in most organisms, especially microbial eukaryotes. In this study, we explored these questions by investigating the reaction norm, regulation, and evolution of phenotypic plasticity in the cosmopolitan marine free-living ciliates Glauconema spp., which undergo significant phenotypic changes in response to food shortages. This study led to the de novo assembly of macronuclear genomes using long-read sequencing, identified hundreds of differentially expressed genes associated with phenotypic plasticity in different life stages, validated the function of two of these genes, and revealed that the reaction norm of body shape in response to food density follows a power-law distribution. Purifying selection may be the dominant evolutionary force acting on the genes associated with phenotypic plasticity, and the overall data support the hypothesis that phenotypic plasticity is a trait maintained by natural selection. This study provides novel insight into the developmental genetics of phenotypic plasticity in non-model unicellular eukaryotes and sheds light on the complexity and long evolutionary history of this important survival strategy.
表型可塑性涉及在无基因变化情况下的表型转变，它可能是生物体在复杂且高度波动的环境中生存的一种策略。然而，在大多数生物体中，尤其是微生物真核生物，其反应规范、分子基础及进化仍不清楚。在本研究中，我们通过研究全球分布的海洋自由生活纤毛虫Glauconema spp. 的表型可塑性的反应规范、调控及进化来探讨这些问题，该纤毛虫会因食物短缺而发生显著的表型变化。本研究利用长读长测序从头组装了大核基因组，鉴定出数百个与不同生命阶段表型可塑性相关的差异表达基因，验证了其中两个基因的功能，并揭示了体型对食物密度的反应规范遵循幂律分布。纯化选择可能是作用于与表型可塑性相关基因的主要进化力量，总体数据支持表型可塑性是一种由自然选择维持的性状这一假说。本研究为非模式单细胞真核生物表型可塑性的发育遗传学提供了新见解，并揭示了这一重要生存策略的复杂性和漫长进化历史。
