Liu Zhilei, Li Yuanjing, Ma Lina, Wei Haichao, Zhang Jianfeng, He Xingyuan, Tian Chunjie
1 Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, Jilin 130102, China;
Mol Plant Microbe Interact. 2015 Apr;28(4):408-19. doi: 10.1094/MPMI-09-14-0251-R.
Mitogen-activated protein kinase (MAPK) cascades play important roles in the stress response in both plants and microorganisms. The mycorrhizal symbiosis established between arbuscular mycorrhizal fungi (AMF) and plants can enhance plant drought tolerance, which might be closely related to the fungal MAPK response and the molecular dialogue between fungal and soybean MAPK cascades. To verify the above hypothesis, germinal Glomus intraradices (syn. Rhizophagus irregularis) spores and potted experiments were conducted. The results showed that AMF GiMAPKs with high homology with MAPKs from Saccharomyces cerevisiae had different gene expression patterns under different conditions (nitrogen starvation, abscisic acid treatment, and drought). Drought stress upregulated the levels of fungi and soybean MAPK transcripts in mycorrhizal soybean roots, indicating the possibility of a molecular dialogue between the two symbiotic sides of symbiosis and suggesting that they might cooperate to regulate the mycorrhizal soybean drought-stress response. Meanwhile, the changes in hydrogen peroxide, soluble sugar, and proline levels in mycorrhizal soybean as well as in the accelerated exchange of carbon and nitrogen in the symbionts were contributable to drought adaptation of the host plants. Thus, it can be preliminarily inferred that the interactions of MAPK signals on both sides, symbiotic fungus and plant, might regulate the response of symbiosis and, thus, improve the resistance of mycorrhizal soybean to drought stress.
丝裂原活化蛋白激酶（MAPK）级联反应在植物和微生物的应激反应中都起着重要作用。丛枝菌根真菌（AMF）与植物之间建立的菌根共生关系可以增强植物的耐旱性，这可能与真菌的MAPK反应以及真菌和大豆MAPK级联反应之间的分子对话密切相关。为了验证上述假设，进行了萌发的根内球囊霉（同物异名：不规则球囊霉）孢子和盆栽实验。结果表明，与酿酒酵母的MAPK具有高度同源性的AMF GiMAPKs在不同条件下（氮饥饿、脱落酸处理和干旱）具有不同的基因表达模式。干旱胁迫上调了菌根化大豆根中真菌和大豆MAPK转录本的水平，这表明共生双方之间存在分子对话的可能性，并表明它们可能协同调节菌根化大豆的干旱胁迫反应。同时，菌根化大豆中过氧化氢、可溶性糖和脯氨酸水平的变化以及共生体中碳和氮交换的加速有助于宿主植物适应干旱。因此，可以初步推断，共生真菌和植物双方的MAPK信号相互作用可能调节共生反应，从而提高菌根化大豆对干旱胁迫的抗性。
