Quantitative morphological phenomics of rice G protein mutants portend autoimmunity
Quantitative morphological phenomics of rice G protein mutants portend autoimmunity
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DOI：
10.1016/j.ydbio.2019.09.007
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发表时间：
2020-01-01
影响因子：
2.7
通讯作者：
Jones, Alan M.
中科院分区：
文献类型：
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作者：
Urano, Daisuke;Leong, Richalynn;Jones, Alan M.
由G α、G β和G γ亚基组成的异源三聚体G蛋白复合物在植物的结构发育中起一定作用，但这种作用可能是间接的，因为功能丧失突变不会改变身体平面，胚后器官仅在形态上不同，而不是在它们的身份上。这种不确定性已被以下事实所加剧：谷物中G β亚基的丧失而不是拟南芥中的G β亚基的丧失是幼苗致死的，而玉米G α亚基的丧失赋予生殖器官的多产性。在这项研究中，我们全面剖析了水稻G α-null和可行的G β-RNAi“敲低”突变体的根和茎的结构性状，并发现了由G β-RNAi引起的不同于拟南芥直向同源物的异常形态。水稻G β-RNAi突变体表现出减少的地上部分的径向生长以及更紧凑的根构型，其中较小的根质量似乎主要是由于在土壤中生长时坏死增加。此外，对水稻根系构型的三维分析表明，G β-RNAi植物较小的根构型也是由于根伸长和不定根形成减少所致。这与促进细胞增殖的拟南芥G β无效突变形成对比。存在升高的细胞衰老活性，其通过伊文思蓝染色可视化并且从细胞死亡标记基因的表达分析推断。我们提出，水稻G β-RNAi植物的形态表型主要与介导的各种压力和细胞衰老，与拟南芥G β在发展中的间接作用，其中orthopathic基因切除主要赋予改变细胞增殖一致。我们还阐述了我们的推测性工作假设，即细胞分裂是一种压力，因此由于G蛋白突变体对压力的反应受损，表现为形态和结构的改变，但不是身体计划或器官身份的改变。
The heterotrimeric G protein complex, composed of G alpha, G beta, and G gamma subunits, plays some role in structural development in plants but this role could be indirect because loss-of-function mutations do not alter the body plan and post-embryonic organs differ only morphologically and not in their identity. This uncertainty has been compounded by the fact that loss of the G beta subunit in cereals, but not Arabidopsis, is seedling lethal and that loss of maize G alpha subunit confers prolificacy of a reproductive organ. In this study, we comprehensively profiled the root and shoot structural traits of rice G alpha-null and viable G beta-RNAi "knockdown" mutants, and found anomalous morphologies caused by G beta-RNAi that are distinct from the Arabidopsis orthologue. The rice G beta-RNAi mutant exhibited reduced radial growth of aerial parts as well as a more compact root architecture, among which smaller root mass seems mainly due to increased necrosis when grown on soil. In addition, three dimensional analyses of rice root system architecture revealed that the smaller root architecture of G beta-RNAi plant is also due to both reduced root elongation and adventitious root formation. This contrasts to the Arabidopsis G beta-null mutation that promotes cell proliferation. There is elevated cell senescence activity both visualized by Evans Blue staining and inferred from an expression analysis of cell-death marker genes. We propose that the morphological phenotypes of rice G beta-RNAi plants are predominantly associated with the mediation of various stresses and cell senescence, consistent with an indirect role for Arabidopsis G beta in development where the orthologous gene ablation mainly confers altered cell proliferation. We also elaborate our speculative working hypothesis that cell division is a type of stress and as such due to impairment in responding to stress in the G protein mutants, manifests as altered morphology and architecture but not an altered body plan or organ identities.