Transgenic Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) Overexpressing S-Adenosylmethionine Decarboxylase (SAMDC) Gene for Improved Cold Tolerance Through Involvement of H2O2 and NO Signaling
Transgenic Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) Overexpressing S-Adenosylmethionine Decarboxylase (SAMDC) Gene for Improved Cold Tolerance Through Involvement of H2O2 and NO Signaling
复制标题
转基因蜈蚣 (Eremochloa ophiuroides [Munro] Hack.) 过表达 S-腺苷甲硫氨酸脱羧酶 (SAMDC) 基因，通过参与 H2O2 和 NO 信号传导提高耐冷性
DOI：
10.3389/fpls.2017.01655
复制
发表时间：
2017-09-22
影响因子：
5.6
通讯作者：
Lu, Shaoyun
中科院分区：
文献类型：
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作者：
Luo, Jianhao;Liu, Mingxi;Lu, Shaoyun
假俭草(Eemochloa oguroides[Munro]Hack.)是一种重要的暖季型草坪草。本研究以狗牙根S腺苷甲硫氨酸脱羧酶基因(CDSAMDC1.)为外源基因，通过低温诱导获得了高表达狗牙根的转基因假俭草植株。与野生型(WT)相比，转基因植株的cdSAMDC1转录本、精胺(Spd)和精蛋白(Spm)水平较高，耐冷性和冷冻性增强。转基因植株的多胺氧化酶(PAO)活性和H_2O_2水平高于野生型植株，而转基因植株的多胺氧化酶活性和H_2O_2水平可被甲基乙醛双鸟苷或SAMDC的抑制剂MGBG所阻断，表明PAO和H_2O_2的增加是由CDSAMDC_1表达的结果。此外，转基因植株具有较高的硝酸还原酶(NR)活性和一氧化氮(NO)浓度。MGBG和抗坏血酸(AsA)(H_2O_2的清除剂)可阻断NR活性的增加，而NO水平的增加可被MGBG、ASA和NR的抑制剂阻断，表明NR产生的NO的增加依赖于H_2O_2，这是由于CDSAMDC1的表达所致。转基因植株的超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性高于野生型植株，MGBG、AsA、NR抑制剂和NO清除剂可阻断这两种酶活性的提高，表明转基因植株的SOD和CAT活性的提高依赖于CDSAMDC1、H_2O_2和NR来源的NO的表达。我们的结果表明，在转基因植物中，耐冷性的提高与PAO催化H_2O_2的产生有关，而H_2O_2的产生又导致了NR产生的NO的产生和抗氧化酶活性的诱导。
Centipedegrass (Eremochloa ophiuroides [Munro] Hack.) is an important warm-season turfgrass species. Transgenic centipedgrass plants overexpressing S-adenosylmethionine decarboxylase from bermudagrass (CdSAMDC1) that was induced in response to cold were generated in this study. Higher levels of CdSAMDC1 transcript and sperimidine (Spd) and spermin (Spm) concentrations and enhanced freezing and chilling tolerance were observed in transgenic plants as compared with the wild type (WT). Transgenic plants had higher levels of polyamine oxidase (PAO) activity and H2O2 than WT, which were blocked by pretreatment with methylglyoxal bis (guanylhydrazone) or MGBG, inhibitor of SAMDC, indicating that the increased PAO and H2O2 were a result of expression of CdSAMDC1. In addition, transgenic plants had higher levels of nitrate reductase (NR) activity and nitric oxide (NO) concentration. The increased NR activity were blocked by pretreatment with MGBG and ascorbic acid (AsA), scavenger of H2O2, while the increased NO level was blocked by MGBG, AsA, and inhibitors of NR, indicating that the enhanced NR-derived NO was dependent upon H2O2, as a result of expression CdSAMDC1. Elevated superoxide dismutase (SOD) and catalase (CAT) activities were observed in transgenic plants than in WT, which were blocked by pretreatment with MGBG, AsA, inhibitors of NR and scavenger of NO, indicating that the increased activities of SOD and CAT depends on expression of CdSAMDC1, H2O2, and NR-derived NO. Our results suggest that the elevated cold tolerance was associated with PAO catalyzed production of H2O2, which in turn led to NR-derived NO production and induced antioxidant enzyme activities in transgenic plants.