Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Sciences, Nanjing Normal University, Nanjing, China.
Plant Cell Environ. 2019 Dec;42(12):3208-3226. doi: 10.1111/pce.13636. Epub 2019 Aug 16.
The role of flowering in root-fungal symbiosis is not well understood. Because flowering and fungal symbionts are supported by carbohydrates, we hypothesized that flowering modulates root-beneficial fungal associations through alterations in carbohydrate metabolism and transport. We monitored fungal colonization and soluble sugars in the roots of Arabidopsis thaliana following inoculation with a mutualistic fungus Phomopsis liquidambari across different plant developmental stages. Jasmonate signalling of wild-type plants, sugar transport, and root invertase of wild-type and jasmonate-insensitive plants were exploited to assess whether and how jasmonate-dependent sugar dynamics are involved in flowering-mediated fungal colonization alterations. We found that flowering restricts root-fungal colonization and activates root jasmonate signalling upon fungal inoculation. Jasmonates reduce the constitutive and fungus-induced accumulation of root glucose and fructose at the flowering stage. Further experiments with sugar transport and metabolism mutant lines revealed that root glucose and fructose positively influence fungal colonization. Diurnal, jasmonate-dependent inhibitions of sugar transport and soluble invertase activity were identified as likely mechanisms for flowering-mediated root sugar depletion upon fungal inoculation. Collectively, our results reveal that flowering drives root-fungus cooperation loss, which is related to jasmonate-dependent root soluble sugar depletion. Limiting the spread of root-fungal colonization may direct more resources to flower development.
开花在根-真菌共生中的作用尚不清楚。由于开花和真菌共生体依赖碳水化合物提供支持，我们假设开花通过改变碳水化合物代谢和运输来调节根有益真菌的共生关系。我们在不同的植物发育阶段，用互养真菌拟茎点霉对拟南芥进行接种，监测真菌定殖和根中的可溶性糖。利用野生型植物的茉莉酸信号、糖转运和野生型及茉莉酸不敏感型植物的根转化酶，评估茉莉酸依赖的糖动态是否以及如何参与开花介导的真菌定殖改变。我们发现，开花限制了根-真菌的定殖，并在真菌接种时激活了根中的茉莉酸信号。茉莉酸减少了开花阶段根葡萄糖和果糖的组成型和真菌诱导型积累。进一步用糖转运和代谢突变体系进行的实验表明，根葡萄糖和果糖正向影响真菌定殖。昼夜节律、茉莉酸依赖性糖转运和可溶性转化酶活性的抑制被确定为真菌接种时开花介导的根糖耗竭的可能机制。总的来说，我们的结果表明，开花导致根-真菌合作的丧失，这与茉莉酸依赖的根可溶性糖耗竭有关。限制根-真菌定殖的扩散可能会将更多的资源引导到花的发育上。
