Dual Roles of OsGH3.2 in Modulating Rice Root Morphology and Affecting Arbuscular Mycorrhizal Symbiosis.
Dual Roles of OsGH3.2 in Modulating Rice Root Morphology and Affecting Arbuscular Mycorrhizal Symbiosis.
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OsGH3.2在调节水稻根部形态和影响丛枝菌根共生中的双重作用
DOI：
10.3389/fpls.2022.853435
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发表时间：
2022
影响因子：
5.6
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中科院分区：
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几种被子植物GH3 （GRETCHEN HAGEN 3）基因，包括番茄SlGH3.4和水稻OsGH3.2，在丛枝菌根（AM）共生过程中被诱导，但其功能仍不清楚。最近有研究认为，番茄SlGH3.4通过降低定植细胞的生长素水平负向调节丛枝生长。本研究通过获得水稻Osgh3.2 pro:β-glucuronidase （GUS）转基因植株，并通过CRISPR/Cas9技术产生Osgh3.2突变体，通过时间过程实验研究Osgh3.2在水稻根系形态调控和AM共生中的作用。与SlGH3.4不同，OsGH3.2在水稻幼嫩侧根中非共生表达，其突变导致根结构“浅”。在共生条件下也观察到这种根形态变化，这可能促进了AM真菌的定植，因为突变体在早期表现出比野生型更高的定植水平和丛枝发生率。与SlGH3.4相似，OsGH3.2在已形成成熟丛管的皮质细胞中表现出共生表达。在共生后期，Osgh3.2突变体表现出比野生型更长的皮质细胞和更大的丛集，表明定殖细胞中的生长素水平升高。综上所述，这些结果揭示了OsGH3.2在调节水稻根构型和控制丛枝细胞生长素水平方面的非共生和共生作用，从而进一步影响定植率和丛枝表型。
Several angiosperm GRETCHEN HAGEN 3 (GH3) genes, including tomato SlGH3.4 and rice OsGH3.2 are induced during arbuscular mycorrhizal (AM) symbiosis, but their functions remain largely unclear. Recently, tomato SlGH3.4 was suggested to negatively regulate arbuscule incidence via decreasing auxin levels in colonized cells. In this study, by acquiring rice OsGH3.2pro:β-glucuronidase (GUS) transgenic plants and generating Osgh3.2 mutants via CRISPR/Cas9 technique, the roles of OsGH3.2 in modulating rice root morphology and affecting AM symbiosis were investigated through time course experiments. Unlike SlGH3.4, OsGH3.2 showed asymbiotic expression in rice young lateral roots, and its mutation resulted in a “shallow” root architecture. Such root morphological change was also observed under symbiotic condition and it likely promoted AM fungal colonization, as the mutants exhibited higher colonization levels and arbuscule incidence than wild-type at early stages. Similar to SlGH3.4, OsGH3.2 showed symbiotic expression in cortical cells that have formed mature arbuscules. At late stages of symbiosis, Osgh3.2 mutants showed elongated cortical cells and larger arbuscules than wild-type, indicating elevated auxin level in the colonized cells. Together, these results revealed both asymbiotic and symbiotic roles of OsGH3.2 in modulating rice root architecture and controlling auxin levels in arbusculated cells, which further affected colonization rate and arbuscule phenotype.