Plant Physiology and Biochemistry Division, Department of Botany, University of Calicut, C.U. Campus P.O., Kerala-673635, India.
Plant Physiology and Biochemistry Division, Department of Botany, University of Calicut, C.U. Campus P.O., Kerala-673635, India; and Corresponding author. Email:
Funct Plant Biol. 2019 Apr;46(5):455-466. doi: 10.1071/FP18258.
UV-B radiation is a major abiotic stress factor that adversely affects the growth and productivity of crop plants including rice (Oryza sativa L.). However, on the other hand, lower doses of UV-B radiation applied to seeds can have a priming effect on plants emerging from it. In this study, seeds of O. sativa var. kanchana were primed with UV-B radiation (6 kJ m-2) and were further subjected to NaCl, polyethylene glycol 6000 (PEG) and UV-B stress. The effects of UV-B priming in imparting NaCl, PEG and UV-B stress tolerance to rice seedlings were analysed through various photosynthetic features and antioxidative mechanisms. PSI and PSII activity levels as well as chl a fluorescence were found to be significantly higher in the UV-B primed and unstressed seedlings. When stress (NaCl, PEG and high UV-B) was imposed, increased PSI and PSII activity levels, chl a fluorescence and metabolite accumulation (proline, total phenolics and sugar) as well as nonenzymatic (ascorbate and glutathione) and enzymatic (superoxide dismutase, catalase, ascorbate peroxidase) antioxidants were recorded in UV-B primed and NaCl-stressed plants followed by UV-B primed and UV-B-stressed plants, and primed and PEG-stressed, compared with unprimed and stressed conditions. The results indicate that UV-B priming in rice seedlings effectively enhances the NaCl stress tolerance potential in rice to a greater extent than UV-B and PEG stress tolerance potential. The cost-effectiveness of UV-B seed priming is predominantly clear from the differing tolerance responses of rice seedlings exposed to different stress conditions.
UV-B 辐射是一种主要的非生物胁迫因素，它会对包括水稻（Oryza sativa L.）在内的作物生长和生产力产生不利影响。然而，另一方面，较低剂量的 UV-B 辐射应用于种子可以对从中萌发的植物产生引发效应。在这项研究中，用 UV-B 辐射（6 kJ m-2）对 O. sativa var. kanchana 的种子进行了引发处理，然后进一步对其进行 NaCl、聚乙二醇 6000（PEG）和 UV-B 胁迫处理。通过各种光合作用特征和抗氧化机制分析了 UV-B 引发对水稻幼苗赋予 NaCl、PEG 和 UV-B 胁迫耐受性的影响。发现 UV-B 引发和未受胁迫的幼苗中 PSI 和 PSII 活性水平以及 chl a 荧光显著更高。当施加胁迫（NaCl、PEG 和高 UV-B）时，UV-B 引发和 NaCl 胁迫的植物中 PSI 和 PSII 活性水平、chl a 荧光以及代谢物积累（脯氨酸、总酚和糖）以及非酶（抗坏血酸和谷胱甘肽）和酶（超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶）抗氧化剂的增加幅度比未引发和受胁迫的条件更大，其次是 UV-B 引发和 UV-B 胁迫的植物，然后是引发和 PEG 胁迫的植物。结果表明，UV-B 引发在水稻幼苗中有效地增强了其对 NaCl 胁迫的耐受性，比 UV-B 和 PEG 胁迫的耐受性更强。从不同胁迫条件下暴露的水稻幼苗的不同耐受反应可以明显看出，UV-B 种子引发的成本效益更高。
