Liang Sheng-Min, Abeer Hashem, Fathi Abd Allah Elsayed, Wu Qiang-Sheng
Hubei Key Laboratory of Spices & Horticultural Plant Germplasm Innovation & Utilization, College of Horticulture and Gardening, Yangtze University, Jingzhou, Hubei 434025, China.
Department of Botany and Microbiology, College of Science, King Saud University, PO Box 2460, Riyadh 11451, Saudi Arabia.
Tree Physiol. 2025 Feb 3;45(2). doi: 10.1093/treephys/tpaf013.
Root-associated endophytic fungi can create symbiotic relationships with trees to enhance stress tolerance, but the underlying mechanisms, especially with regard to waterlogging tolerance, remain unclear. This study aimed to elucidate the effects of Funneliformis mosseae and Serendipita indica on the growth, root cross-section structure, and root transcriptional responses of peach under waterlogging stress, with a focus on polyamine and proline metabolism. Genes and transcription factors associated with secondary cell wall biosynthesis were selected, and their expression profiles were analyzed. Funneliformis mosseae significantly increased the height, stem diameter and leaf number of peach seedlings subjected to 2 weeks of waterlogging stress, whereas S. indica only significantly improved stem diameter. Both fungal species substantially increased root diameter, stele diameter, the number of late metaxylem inside the stele and late metaxylem diameter, thus improving aeration within inoculated roots under waterlogging stress. Transcriptomic analysis of waterlogged roots identified 5425 and 5646 differentially expressed genes following inoculation with F. mosseae and S. indica, respectively. The arginine and proline metabolism and arginine biosynthesis pathways were enriched following fungal inoculations. Both fungi reduced the conversion of glutamate and ornithine for proline synthesis. However, S. indica promoted peptide-to-proline conversion by up-regulating the expression of PIPs. Although both fungi promoted the expression of genes involved in arginine and ornithine synthesis pathway, only F. mosseae led to increased levels of arginine and ornithine. Additionally, F. mosseae promoted the accumulation of putrescine and maintained polyamine homeostasis by down-regulating PAO2 and SAMDC. Moreover, F. mosseae facilitated the metabolism of cadaverine. In conclusion, both F. mosseae and S. indica formed symbiotic relationships with peach plants, with F. mosseae primarily improving polyamine accumulation and S. indica predominantly facilitating proline accumulation for enhanced waterlogging resistance.
根际内生真菌可与树木建立共生关系以增强胁迫耐受性，但其潜在机制，尤其是耐涝性方面的机制仍不清楚。本研究旨在阐明摩西管柄囊霉和印度梨形孢对淹水胁迫下桃树生长、根横截面结构及根转录反应的影响，重点关注多胺和脯氨酸代谢。选择了与次生细胞壁生物合成相关的基因和转录因子，并分析了它们的表达谱。摩西管柄囊霉显著增加了遭受2周淹水胁迫的桃树苗的高度、茎直径和叶片数量，而印度梨形孢仅显著提高了茎直径。两种真菌均大幅增加了根直径、中柱直径、中柱内后生木质部数量和后生木质部直径，从而改善了淹水胁迫下接种根内的通气状况。对淹水根的转录组分析表明，接种摩西管柄囊霉和印度梨形孢后分别鉴定出5425个和5646个差异表达基因。真菌接种后，精氨酸和脯氨酸代谢以及精氨酸生物合成途径得到富集。两种真菌均减少了用于脯氨酸合成的谷氨酸和鸟氨酸的转化。然而，印度梨形孢通过上调PIPs的表达促进了肽向脯氨酸的转化。虽然两种真菌均促进了参与精氨酸和鸟氨酸合成途径的基因表达，但只有摩西管柄囊霉导致精氨酸和鸟氨酸水平升高。此外，摩西管柄囊霉促进了腐胺的积累，并通过下调PAO2和SAMDC维持多胺稳态。而且，摩西管柄囊霉促进了尸胺的代谢。总之，摩西管柄囊霉和印度梨形孢均与桃树形成了共生关系，其中摩西管柄囊霉主要促进多胺积累，而印度梨形孢主要促进脯氨酸积累以增强耐涝性。
