Kobae Yoshihiro, Ohmori Yoshihiro, Saito Chieko, Yano Koji, Ohtomo Ryo, Fujiwara Toru
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan (Y.K., Y.O., K.Y., T.F.); Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan (C.S.); andNational Agriculture and Food Research Organization, Hokkaido Agricultural Research Center Agro-Environmental Research Division, Toyohira, Sapporo, Hokkaido, 062-8555 Japan (Y.K., R.O.)
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan (Y.K., Y.O., K.Y., T.F.); Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan (C.S.); andNational Agriculture and Food Research Organization, Hokkaido Agricultural Research Center Agro-Environmental Research Division, Toyohira, Sapporo, Hokkaido, 062-8555 Japan (Y.K., R.O.).
Plant Physiol. 2016 May;171(1):566-79. doi: 10.1104/pp.16.00127. Epub 2016 Mar 15.
Phosphorus (P) is a crucial nutrient for plant growth, but its availability to roots is limited in soil. Arbuscular mycorrhizal (AM) symbiosis is a promising strategy for improving plant P acquisition. However, P fertilizer reduces fungal colonization (P inhibition) and compromises mycorrhizal P uptake, warranting studies on the mechanistic basis of P inhibition. In this study, early morphological changes in P inhibition were identified in rice (Oryza sativa) using fungal cell wall staining and live-cell imaging of plant membranes that were associated with arbuscule life cycles. Arbuscule density decreased, and aberrant hyphal branching was observed in roots at 5 h after P treatment. Although new arbuscule development was severely inhibited, preformed arbuscules remained intact and longevity remained constant. P inhibition was accelerated in the rice pt11-1 mutant, which lacks P uptake from arbuscule branches, suggesting that mature arbuscules are stabilized by the symbiotic P transporter under high P condition. Moreover, P treatment led to increases in the number of vesicles, in which lipid droplets accumulated and then decreased within a few days. The development of new arbuscules resumed within by 2 d. Our data established that P strongly and temporarily inhibits new arbuscule development, but not intraradical accommodation of AM fungi.
磷（P）是植物生长的关键养分，但其在土壤中根系可利用性有限。丛枝菌根（AM）共生是提高植物磷吸收的一种有前景的策略。然而，磷肥会降低真菌定殖（磷抑制）并损害菌根磷吸收，因此有必要对磷抑制的机制基础进行研究。在本研究中，利用真菌细胞壁染色和与丛枝生命周期相关的植物膜的活细胞成像，在水稻（Oryza sativa）中确定了磷抑制的早期形态变化。磷处理5小时后，根中丛枝密度降低，并观察到异常的菌丝分支。尽管新丛枝的发育受到严重抑制，但已形成的丛枝保持完整，寿命保持不变。在缺乏从丛枝分支吸收磷的水稻pt11-1突变体中，磷抑制作用加速，这表明在高磷条件下，成熟丛枝由共生磷转运体稳定。此外，磷处理导致泡囊数量增加，其中脂滴积累，然后在几天内减少。新丛枝的发育在2天内恢复。我们的数据表明，磷强烈且暂时抑制新丛枝的发育，但不抑制AM真菌在根内的定殖。
