Yang Han, Peng Lirun, Chen Liyan, Zhang Lijuan, Kan Liping, Shi Yujie, Mei Xinlan, Malladi Anish, Xu Yangchun, Dong Caixia
Jiangsu Provincial Key Lab of Solid Organic Waste Utilization, Jiangsu Collaborative Innovation Center of Solid Organic Wastes, Educational Ministry Engineering Center of Resource-saving Fertilizers, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, PR China.
Horticulture Department, University of Georgia, Athens, GA, 30602, United States.
Plant Physiol Biochem. 2023 Mar;196:43-54. doi: 10.1016/j.plaphy.2023.01.024. Epub 2023 Jan 16.
To investigate K absorption and transport mechanisms by which pear rootstock genotypes respond to low-K stress, seedlings of a potassium-efficient pear rootstock, Pyrus ussuriensis, and a potassium-sensitive rootstock, Pyrus betulifolia, were supplied with different K concentrations in solution culture. Significant differences in the absorption rate, V and K between the genotypes indicate that P. ussuriensis acclimatizes more readily to low-K stress by regulating its absorption and internal cycling. We also found that the K content in the leaves of P. betulifolia was significantly lower than that of P. ussuriensis, and the proportion of K that was returned to root from shoot, relative to K that was transported from root to shoot, was greater in P. ussuriensis, which suggests that P. ussuriensis more efficiently recycles and reuses K. When the transcriptomes of the two genotypes were compared, we found that photosynthetic genes such as CABs (Chlorophyll a/b-binding proteins), Lhcbs (Photosystem II-related proteins), and Psas (Photosystem Ⅰ associated proteins) displayed lower expression in leaves of P. betulifolia under no-K conditions, but not in P. ussuriensis. However, in the root of P. ussuriensis, carbon metabolism-related genes SS (Sucrose Synthase), HK (HexoKinase) and SDH (Sorbitol Dehydrogenase) and components of the TCA cycle (Tricarboxylic Acid cycle) were differentially expressed, indicating that changes in C metabolism may provide energy for increased K cycling in these plants, thereby allowing it to better adapt to the low-K environment. In addition, exogenous supply of various sugars to the roots influenced K influx, supporting the conclusion that sugar metabolism in roots significantly affects K absorption in pear.
为研究梨砧木基因型对低钾胁迫响应的钾吸收和转运机制，在溶液培养中为高效钾利用梨砧木秋子梨和低钾敏感砧木杜梨的幼苗提供不同钾浓度。基因型之间在吸收速率、V和K方面存在显著差异，表明秋子梨通过调节其吸收和内部循环更容易适应低钾胁迫。我们还发现，杜梨叶片中的钾含量显著低于秋子梨，且秋子梨中从地上部返回根部的钾占从根部运输到地上部的钾的比例更大，这表明秋子梨能更有效地循环利用钾。比较两种基因型的转录组时，我们发现，在无钾条件下，杜梨叶片中诸如CABs（叶绿素a/b结合蛋白）、Lhcbs（光系统II相关蛋白）和Psas（光系统I相关蛋白）等光合基因表达较低，但秋子梨中并非如此。然而，在秋子梨的根中，碳代谢相关基因SS（蔗糖合酶）、HK（己糖激酶）和SDH（山梨醇脱氢酶）以及三羧酸循环（TCA循环）的组分差异表达，表明碳代谢变化可能为这些植物中增加的钾循环提供能量，从而使其能更好地适应低钾环境。此外，向根部外源供应各种糖类会影响钾流入，支持了根部糖代谢显著影响梨钾吸收这一结论。
