Department of Botany, Ranjan Plant Physiology and Biochemistry Laboratory, University of Allahabad, Allahabad, India.
Department of Botany, Hindu College Moradabad, Mahatma Jyotiba Phule Rohilkhand University, Bareilly, India.
PLoS One. 2021 Jun 22;16(6):e0249230. doi: 10.1371/journal.pone.0249230. eCollection 2021.
Cytokinins (CKs) plays a key role in plant adaptation over a range of different stress conditions. Here, we analyze the effects of a cytokinin (i.e., kinetin, KN) on the growth, photosynthesis (rate of O2 evolution), PS II photochemistry and AsA-GSH cycle in Trigonella seedlings grown under cadmium (Cd) stress. Trigonella seeds were sown in soil amended with 0, 3 and 9 mg Cd kg-1 soil, and after 15 days resultant seedlings were sprayed with three doses of KN, i.e.,10 μM (low, KNL), 50 μM (medium, KNM) and 100 μM (high, KNH); subsequent experiments were performed after 15 days of KN application, i.e., 30 days after sowing. Cadmium toxicity induced oxidative damage as shown by decreased seedling growth and photosynthetic pigment production (Chl a, Chl b and Car), rates of O2-evolution, and photochemistry of PS II of Trigonella seedlings, all accompanied by an increase in H2O2 accumulation. Supplementation with doses of KN at KNL and KNM significantly improved the growth and photosynthetic activity by reducing H2O2 accumulation through the up-regulation AsA-GSH cycle. Notably, KNL and KNM doses stimulated the rate of enzyme activities of APX, GR and DHAR, involved in the AsA-GSH cycle thereby efficiently regulates the level of AsA and GSH in Trigonella grown under Cd stress. The study concludes that KN can mitigate the damaging effects of Cd stress on plant growth by maintaining the redox status (>ratios: AsA/DHA and GSH/GSSG) of cells through the regulation of AsA-GSH cycle at 10 and 50 μM KN under Cd stress conditions. At 100 μM KN, the down-regulation of AsA-GSH cycle did not support the growth and PS II activity of the test seedlings.
细胞分裂素(CKs)在植物适应多种不同胁迫条件方面发挥着关键作用。在这里,我们分析了细胞分裂素(即激动素,KN)对镉(Cd)胁迫下野豌豆幼苗生长、光合作用(O2 释放速率)、PS II 光化学和 AsA-GSH 循环的影响。将野豌豆种子播种在添加了 0、3 和 9mg Cd kg-1 土壤的土壤中,15 天后,用三剂 KN 喷洒所得幼苗,即 10μM(低浓度,KNL)、50μM(中浓度,KNM)和 100μM(高浓度,KNH);在 KN 应用 15 天后,即在播种后 30 天进行后续实验。Cd 毒性表现为幼苗生长和光合色素(Chl a、Chl b 和 Car)产生、O2 释放速率和 PS II 光化学降低,同时 H2O2 积累增加,表明氧化损伤。用 KNL 和 KNM 补充 KN 可显著通过上调 AsA-GSH 循环减少 H2O2 积累来改善生长和光合作用。值得注意的是,KNL 和 KNM 剂量通过刺激 APX、GR 和 DHAR 等参与 AsA-GSH 循环的酶活性,刺激 Cd 胁迫下野豌豆的生长速率,从而有效调节 AsA 和 GSH 的水平。研究得出结论,KN 可以通过调节 AsA-GSH 循环来维持细胞的氧化还原状态(>比值:AsA/DHA 和 GSH/GSSG),从而在 10 和 50μM KN 下减轻 Cd 胁迫对植物生长的破坏作用。在 100μM KN 下,下调 AsA-GSH 循环不利于试验幼苗的生长和 PS II 活性。