Zou Ying-Ning, Xu Yong-Jie, Liu Rui-Cheng, Huang Guang-Ming, Kuča Kamil, Srivastava Anoop Kumar, Hashem Abeer, Abd Allah Elsayed Fathi, Wu Qiang-Sheng
Tibet Plateau Walnut Industry Research Institute, College of Horticulture and Gardening, Yangtze University, Jingzhou, Hubei, China.
Hubei Academy of Foresty, Wuhan, China.
Front Plant Sci. 2023 Feb 23;14:1140467. doi: 10.3389/fpls.2023.1140467. eCollection 2023.
Walnut () is an important nut tree species in the world, whereas walnut trees often face inadequate phosphorus (P) levels of soil, negatively limiting its growth and yield. Arbuscular mycorrhizal fungi (AMF) can colonize walnut roots, but whether and how AMF promotes walnut growth, physiological activities, and P acquisition is unclear. The present study aimed to evaluate the effects of on plant growth, chlorophyll component concentrations, leaf gas exchange, sugar and P concentrations, and expression of () and () genes in leaves of . var. Liaohe 1 seedling under moderate (100 μmol/L P) and low P (1 μmol/L P) levels conditions. Three months after inoculation, the root mycorrhizal colonization rate and soil hyphal length were 45.6-53.2% and 18.7-39.9 cm/g soil, respectively, and low P treatment significantly increased both root mycorrhizal colonization rate and soil hyphal length. Low P levels inhibited plant growth (height, stem diameter, and total biomass) and leaf gas exchange (photosynthetic rate, transpiration rate and stomatal conductance), while AMF colonization significantly increased these variables at moderate and low P levels. Low P treatment limited the level of chlorophyll , but AMF colonization did not significantly affect the level of chlorophyll components, independent on soil P levels. AMF colonization also increased leaf glucose at appropriate P levels and leaf fructose at low P levels than non-AMF treatment. AMF colonization significantly increased leaf P concentration by 21.0-26.2% than non-AMF colonization at low and moderate P levels. Low P treatment reduced the expression of leaf , , and in the inoculated plants, whereas AMF colonization up-regulated the expression of leaf , , and at moderate P levels, although AMF did not significantly alter the expression of and at low P levels. It is concluded that AMF improved plant growth, leaf gas exchange, and P acquisition of walnut seedlings at different P levels, where mycorrhizal promotion of P acquisition was dominated by direct mycorrhizal involvement in P uptake at low P levels, while up-regulation of host and expressions at moderate P levels.
核桃（）是世界上一种重要的坚果树种，然而核桃树常常面临土壤磷（P）含量不足的问题，这对其生长和产量产生负面影响。丛枝菌根真菌（AMF）能够定殖在核桃根系上，但AMF是否以及如何促进核桃生长、生理活动和磷吸收尚不清楚。本研究旨在评估在中等（100 μmol/L P）和低磷（1 μmol/L P）水平条件下，对辽核1号核桃幼苗的植株生长、叶绿素组分浓度、叶片气体交换、糖分和磷浓度以及叶片中（）和（）基因表达的影响。接种三个月后，根系菌根定殖率和土壤菌丝长度分别为45.6 - 53.2%和18.7 - 39.9 cm/g土壤，低磷处理显著提高了根系菌根定殖率和土壤菌丝长度。低磷水平抑制了植株生长（株高、茎粗和总生物量）和叶片气体交换（光合速率、蒸腾速率和气孔导度），而AMF定殖在中等和低磷水平下显著提高了这些变量。低磷处理限制了叶绿素的水平，但AMF定殖对叶绿素组分水平没有显著影响，与土壤磷水平无关。与未接种AMF处理相比，在适宜磷水平下，AMF定殖增加了叶片葡萄糖含量，在低磷水平下增加了叶片果糖含量。在低磷和中等磷水平下，AMF定殖使叶片磷浓度比未接种AMF定殖显著提高了21.0 - 26.2%。低磷处理降低了接种植株叶片中、和的表达，而在中等磷水平下，AMF定殖上调了叶片中、和的表达，尽管在低磷水平下AMF对和的表达没有显著改变。研究得出结论，AMF在不同磷水平下改善了核桃幼苗的植株生长、叶片气体交换和磷吸收，其中在低磷水平下菌根对磷吸收的促进作用主要是通过菌根直接参与磷吸收，而在中等磷水平下则是通过上调宿主和的表达。
