60Co-γ辐射及PEG胁迫对桑树幼苗生理特性和相关基因表达的影响

为了探究不同剂量⁶⁰Co-γ辐射和聚乙二醇(PEG)胁迫对桑树幼苗生理特性的影响,筛选有助于增强桑树抗旱性的辐射剂量,以桑树品种桂优12号为试验材料,对种子进行不同剂量(0、100、200、300、400 Gy)⁶⁰Co-γ辐射,用10% PEG模拟干旱胁迫,测定胁迫下桑树幼苗叶片和根部质膜相对透性,丙二醛(MDA)含量,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性,可溶性蛋白和脯氨酸含量,分析氧化物酶基因POD1、超氧化物歧化酶基因sodC和脯氨酸合成关键酶吡咯啉-5-羧酸合成酶基因P5CS的表达水平。结果表明,低剂量⁶⁰Co-γ辐射(≤200 Gy)能够降低桑树幼苗叶片和根中质膜相对透性和MDA含量,提高SOD、POD、CAT活性,增加可溶性蛋白、脯氨酸含量,POD1、sodC、P5CS表达上调,桑树幼苗抗旱性提高;而高剂量⁶⁰Co-γ辐射(≥300 Gy)则加剧了胁迫伤害。综合分析,以200 Gy⁶⁰Co-γ辐射的种子抗旱性最强。本研究为桑树旱地栽培及育种提供了理论参考。

Effects of 60Co-γ Radiation and PEG Stress on Physiological Characteristics and Related Gene Expression of Mulberry Seedlings

To investigate the influences of different irradiation dosages of ⁶⁰Co-γ and PEG stress on the physiological characteristics of mulberry seedlings,and select the optimal radiation dosage for improving the drought resistance of mulberry. Guiyou 12 seeds were irradiated with five doses of ⁶⁰Co-γ rays: 0, 100, 200, 300 and 400 Gy. Under the simulative drought stress of 10% polyethylene glycol (PEG), the relative permeability of plasma membrane, the content of malonaldehyde (MDA), the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and the content of soluble protein and proline in the leaves and roots were measured and the expression levels of peroxidase gene POD1, superoxide dismutase gene sodC and pyrroline-5-carboxylic acid synthetase P5CS which was the key enzyme of proline synthesis were detected. Results indicated that low dose ⁶⁰Co-γ radiation (≤200 Gy) could reduce the relative permeability of plasma membrane and the content of MDA in the leaves and roots of mulberry seedlings, improve the SOD, POD and CAT activity, increase the content of soluble protein and proline, and up-regulate the expression levels of POD1, sodC and P5CS, and so as to improve the drought resistance of mulberry seedlings. While the high dose of ⁶⁰Co-γ radiation (≥300 Gy) aggravated the stress injury. Comprehensive analysis showed that the seeds irradiated with 200 Gy⁶⁰Co-γ had the strongest drought resistance. This study provided theretical references for mulberry cultivation and breeding in drought region.