PROTOPLASMA ：河南农大丨高温干旱胁迫致ABA和ROS积累影响水稻萌发（附NMT实验体系）

主题：高温和干旱胁迫导致水稻脱落酸和活性氧的积累，抑制种子萌发生长

Seed  germination is one of the most important biological processes in the  life cycle of plants, and temperature and water are the two most  critical environmental factors that influence seed germination.

In  the present study, we investigated the roles of the plant hormone  abscisic acid (ABA) and reactive oxygen species (ROS) in high  temperature (HT) and drought-induced inhibition of rice seed  germination. HT and drought stress caused ABA accumulation in seeds and  inhibited seed germination and seedling establishment. Quantitative  real-time polymerase chain reaction analysis revealed that HT and  drought stress induced the expression of OsNCED3, a key gene in ABA  synthesis in rice seeds.

In  addition, ROS (O2•- and H2O2) and malondialdehyde contents were  increased in germinating seeds under HT and drought stress. Moreover, we  adopted the non-invasive micro-test technique to detect H2O2 and Ca2+  fluxes at the site of coleoptile emergence. HT and drought stress  resulted in a H2O2 efflux, but only drought stress significantly induced  Ca2+ influx. Antioxidant enzyme assays revealed that superoxide  dismutase (SOD), peroxidase, catalase (CAT), and ascorbate peroxidase  (APX) activity were reduced by HT and drought stress, consistent with  the expression of OsCu/ZnSOD, OsCATc, and OsAPX2 during seed  germination.

Altogether,  these results suggest that ABA and ROS accumulation under HT and drought  conditions can inhibit rice seed germination and growth.

种子萌发是植物生命周期中最重要的生物过程之一，温度和水是影响种子萌发的两个最关键的环境因素。

在本研究中，我们研究了植物激素脱落酸（ABA）和活性氧（ROS）在高温（HT）和干旱诱导的水稻种子萌发抑制中的作用。 HT和干旱胁迫导致种子中ABA积累，抑制种子萌发和幼苗建立。定量实时聚合酶链反应分析表明，HT和干旱胁迫诱导水稻种子ABA合成中关键基因OsNCED3的表达。

此外，在HT和干旱胁迫下，萌发种子中ROS（O2• - 和H2O2）和丙二醛含量增加。此外，我们采用非侵入性微测试技术检测胚芽鞘出现部位的H2O2和Ca2+通量。 HT和干旱胁迫导致H2O2流出，但只有干旱胁迫才能显着诱导Ca2 +流入。抗氧化酶测定表明，HT和干旱胁迫使超氧化物歧化酶（SOD），过氧化物酶，过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）活性降低，与种子萌发过程中OsCu / ZnSOD，OsCATc和OsAPX2的表达一致。

总之，这些结果表明，在HT和干旱条件下ABA和ROS的积累可以抑制水稻种子的萌发和生长。

结果表明：干旱胁迫显着加剧了发芽种子中胚芽鞘出苗位点的Ca²⁺净吸收（图b），Ca²⁺净吸收量比对照种子高61.2％。同时，HT对Ca²⁺净流入没有显着影响，尽管与对照相比略有下降。 H₂O₂流速在对照组和治疗组之间的方向和大小上显示出显着差异（图c）。对照种子表现出H₂O₂的吸收。然而，在HT和干旱胁迫下，H₂O₂从种子外排到测试溶液中，分别达到1.20和0.44pmol cm-2 s -1。这些结果可能表明H₂O₂外排进一步意味着在HT和干旱胁迫下发芽种子中积累更多的H₂O含量。