College of Grassland Science, Xinjiang Agricultural University, China; Key Laboratory of Grassland Resources and Ecology of Western Arid Region, Ministry of Education, China; Xinjiang Key Laboratory of Grassland Resources and Ecology, Urumqi, 830052, Xiangjiang, China.
College of Grassland Science, Xinjiang Agricultural University, China; Key Laboratory of Grassland Resources and Ecology of Western Arid Region, Ministry of Education, China; Xinjiang Key Laboratory of Grassland Resources and Ecology, Urumqi, 830052, Xiangjiang, China.
J Plant Physiol. 2024 Nov;302:154319. doi: 10.1016/j.jplph.2024.154319. Epub 2024 Jul 30.
Alfalfa often suffers from low temperature during spring rejuvenation, so it is important to improve the cold tolerance of alfalfa leaves for its smooth rejuvenation, and the alternative pathway (AP) could effectively improve the plant's tolerance. In this study, the contribution of AP on spring rejuvenation of alfalfa was investigated in Xinmu No.4 and Gannong No.5 with different fall dormancy levels. Though the protein and AP capacity were decreased during the rejuvenation, the ratio of AP/TP were increased in two alfalfa varieties, compared to those in alfalfa before overwintering. This indicated that AP had positive response to alfalfa rejuvenation. The limitation of AP significantly affected the leaf length, leaf width and growth rate of greening alfalfa, showing that AP played an important role in alfalfa rejuvenation. Inhibition of AP resulted in a significant decrease in Pn, Ci, Gs and stomatal structure deformity, suggestion that AP affected photosynthesis by influencing stomatal development during rejuvenation. AP reduces oxidative damage to PSII core protein repair in alfalfa leaves and optimizes photosynthesis by up-regulating NADP-MDH activity, decreasing the accumulation of excess reducing power in the chloroplasts, and by increasing SOD and POD activities and decreasing the accumulation of hydrogen peroxide. The higher proportion of AP keeps it more tolerant to low temperature for rejuvenation in Xinmu No.4 with a lower fall dormancy level.
紫花苜蓿在春季返青时常遭受低温影响，因此提高其叶片的耐寒性对于顺利返青非常重要，而交替途径（AP）可以有效提高植物的耐受性。本研究以不同秋眠级的新牧 4 号和甘农 5 号为材料，探讨了 AP 对紫花苜蓿春季返青的贡献。尽管在返青过程中蛋白质和 AP 能力下降，但与越冬前的紫花苜蓿相比，两种紫花苜蓿品种的 AP/TP 比值均增加。这表明 AP 对紫花苜蓿返青有积极响应。AP 的限制显著影响了返青紫花苜蓿的叶片长度、叶片宽度和生长速度，表明 AP 在紫花苜蓿返青中发挥了重要作用。AP 抑制导致 Pn、Ci、Gs 显著降低，气孔结构畸形，表明 AP 通过影响返青过程中气孔的发育影响光合作用。AP 减少了 PSII 核心蛋白修复的氧化损伤，通过上调 NADP-MDH 活性、减少叶绿体中过量还原能的积累、增加 SOD 和 POD 活性以及减少过氧化氢的积累，优化了光合作用。较高比例的 AP 使其在秋眠级较低的新牧 4 号中更能耐受低温以进行返青。
