Wang Yutao, Bao Xiaozhe, Li Shaoshan
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education and Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China.
Front Microbiol. 2021 Oct 26;12:756752. doi: 10.3389/fmicb.2021.756752. eCollection 2021.
Arbuscular mycorrhizal fungi (AMF) are present in paddy fields, where they suffer from periodic soil flooding and sometimes shading stress, but their interaction with rice plants in these environments is not yet fully explained. Based on two greenhouse experiments, we examined rice-growth response to AMF under different flooding and/or shading regimes to survey the regulatory effects of flooding on the mycorrhizal responses of rice plants under different light conditions. AMF had positive or neutral effects on the growth and yields of both tested rice varieties under non-flooding conditions but suppressed them under all flooding and/or shading regimes, emphasizing the high importance of flooding and shading conditions in determining the mycorrhizal effects. Further analyses indicated that flooding and shading both reduced the AMF colonization and extraradical hyphal density (EHD), implying a possible reduction of carbon investment from rice to AMF. The expression profiles of mycorrhizal P pathway marker genes ( and ) suggested the P delivery from AMF to rice roots under all flooding and shading conditions. Nevertheless, flooding and shading both decreased the mycorrhizal P benefit of rice plants, as indicated by the significant decrease of mycorrhizal P responses (MPRs), contributing to the negative mycorrhizal effects on rice production. The expression profiles of rice defense marker genes and suggested that regardless of mycorrhizal growth responses (MGRs), AMF colonization triggered the basal defense response, especially under shading conditions, implying the multifaceted functions of AMF symbiosis and their effects on rice performance. In conclusion, this study found that flooding and shading both modulated the outcome of AMF symbiosis for rice plants, partially by influencing the mycorrhizal P benefit. This finding has important implications for AMF application in rice production.
丛枝菌根真菌（AMF）存在于稻田中，它们在稻田中会遭受周期性的土壤淹水，有时还会受到遮荫胁迫，但它们在这些环境中与水稻植株的相互作用尚未得到充分解释。基于两项温室试验，我们研究了在不同淹水和/或遮荫条件下水稻对AMF的生长响应，以探究淹水对不同光照条件下水稻植株菌根响应的调节作用。在非淹水条件下，AMF对两个受试水稻品种的生长和产量具有正向或中性影响，但在所有淹水和/或遮荫条件下均对其产生抑制作用，这强调了淹水和遮荫条件在决定菌根效应方面的高度重要性。进一步分析表明，淹水和遮荫均降低了AMF的定殖率和根外菌丝密度（EHD），这意味着从水稻到AMF的碳投入可能减少。菌根磷途径标记基因（和）的表达谱表明，在所有淹水和遮荫条件下，AMF均向水稻根系输送磷。然而，如菌根磷响应（MPR）显著降低所示，淹水和遮荫均降低了水稻植株的菌根磷效益，这导致了菌根对水稻产量产生负面影响。水稻防御标记基因和的表达谱表明，无论菌根生长响应（MGR）如何，AMF定殖都会引发基础防御反应，尤其是在遮荫条件下，这意味着AMF共生的多方面功能及其对水稻性能的影响。总之，本研究发现，淹水和遮荫均调节了水稻植株AMF共生的结果，部分原因是影响了菌根磷效益。这一发现对AMF在水稻生产中的应用具有重要意义。
