Fan Jing-Wei, Chen Mei, Tian Fuping, Yao Rui, Turner Neil C, Yang Lan, Fang Wan-Ying, Abbott Lynette, Li Feng-Min, Du Yan-Lei
State Key Laboratory of Herbage Improvement and Grassland Agroecosystems, College of Ecology, Lanzhou University, Lanzhou 730000, Gansu Province, China.
The UWA Institute of Agriculture, The University of Western Australia, Crawley, WA 6009, Australia.
J Exp Bot. 2025 Jul 31. doi: 10.1093/jxb/eraf335.
Soil phosphorus (P) deficiency can severely limit crop and forage productivity. With limited P resources, breeding programs to select high-P efficiency (HPE) genotypes have been developed, but the role of arbuscular mycorrhizal fungi (AMF) in altering root morphology and physiology to increase P use efficiency and production remains poorly understood. In this study, we compared mycorrhizal responsiveness, and plasticity of root morphological and physiological traits between two low-P efficiency (LPE) and two HPE alfalfa genotypes under low and high P treatments. Plants were grown either in soil with naturally occurring AMF or in sterilized soil added with AMF-free bacteria. The results indicated that the AMF symbiosis significantly increased alfalfa productivity and physiological P use efficiency by enhancing total root length and root surface area while reducing carboxylate release. Under low P conditions, HPE genotypes with AMF symbiosis showed higher shoot dry weight, greater mycorrhizal responsiveness, thicker and more robust roots, as well as increased carboxylate release compared to LPE genotypes. We conclude that exploitation of the dominant species in indigenous AMF populations and breeding of crop genotypes with high mycorrhizal responsiveness show promising avenues with which to improve forage productivity and alleviate P-limitation in modern agricultural ecosystems.
土壤磷（P）缺乏会严重限制作物和牧草的生产力。由于磷资源有限，已开展了选育高磷效率（HPE）基因型的育种计划，但丛枝菌根真菌（AMF）在改变根系形态和生理以提高磷利用效率和产量方面的作用仍知之甚少。在本研究中，我们比较了两种低磷效率（LPE）和两种HPE苜蓿基因型在低磷和高磷处理下的菌根响应性以及根系形态和生理性状的可塑性。植株种植于含有天然存在的AMF的土壤中或添加了无AMF细菌的灭菌土壤中。结果表明，AMF共生通过增加总根长和根表面积同时减少羧酸盐释放，显著提高了苜蓿的生产力和生理磷利用效率。在低磷条件下，与LPE基因型相比，具有AMF共生的HPE基因型表现出更高的地上部干重、更高的菌根响应性、更粗更健壮的根系以及增加的羧酸盐释放。我们得出结论，利用本地AMF种群中的优势物种以及培育具有高菌根响应性的作物基因型，是提高现代农业生态系统中牧草生产力和缓解磷限制的有前景的途径。
