Endogenous ABA alleviates rice ammonium toxicity by reducing ROS and free ammonium via regulation of the SAPK9-bZIP20 pathway
Endogenous ABA alleviates rice ammonium toxicity by reducing ROS and free ammonium via regulation of the SAPK9-bZIP20 pathway
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内源 ABA 通过调节 SAPK9-bZIP20 途径减少 ROS 和游离铵，从而减轻水稻铵毒性。
DOI：
10.1093/jxb/eraa076
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发表时间：
2020-07-25
影响因子：
6.9
通讯作者：
Shi, Weiming
中科院分区：
文献类型：
--
作者：
Sun, Li;Di, Dong-Wei;Shi, Weiming
铵（NH 4+）是土壤中的主要氮（N）源之一，但在中等浓度下通常已经有毒。植物激素脱落酸（阿坝）在植物对环境胁迫的响应中起着关键作用。但阿坝在高NH_4 ~+胁迫下对水稻（Oryza sativa L.）只是被边缘化了。在这里，我们报告，升高的NH 4+可以显着加速组织阿坝积累。具有高水平（Osaba 8 ox）和低水平（Osphs 3 -1）阿坝的突变体分别表现出对高NH 4+胁迫的耐受性或敏感性增强。此外，阿坝还可通过增强抗氧化剂和谷氨酰胺合成酶（GS）/谷氨酸合成酶（GOGAT）活性，减轻NH 4+诱导的氧化损伤和组织NH 4+积累。利用RNA测序和实时定量PCR方法，我们确定两个基因，OsSAPK 9和OsbZIP 20，高NH 4+和阿坝诱导。我们的数据表明OsSAPK 9与OsbZIP 20相互作用，并且可以磷酸化OsbZIP 20并激活其功能。OsSAPK 9和OsbZIP 20基因敲除后，ABA介导的抗氧化作用和GS/GOGAT活性增强作用消失，且两个突变体对高NH 4+胁迫的敏感性均高于野生型。总而言之，我们的结果表明，阿坝在调节水稻OsSAPK 9-OsbZIP 20途径以提高对高铵胁迫的耐受性方面发挥着积极作用。
Ammonium (NH4+) is one of the principal nitrogen (N) sources in soils, but is typically toxic already at intermediate concentrations. The phytohormone abscisic acid (ABA) plays a pivotal role in responses to environmental stresses. However, the role of ABA under high-NH4+ stress in rice (Oryza sativa L.) is only marginally understood. Here, we report that elevated NH4+ can significantly accelerate tissue ABA accumulation. Mutants with high (Osaba8ox) and low levels of ABA (Osphs3-1) exhibit elevated tolerance or sensitivity to high-NH4+ stress, respectively. Furthermore, ABA can decrease NH4+-induced oxidative damage and tissue NH4+ accumulation by enhancing antioxidant and glutamine synthetase (GS)/glutamate synthetasae (GOGAT) enzyme activities. Using RNA sequencing and quantitative real-time PCR approaches, we ascertain that two genes, OsSAPK9 and OsbZIP20, are induced both by high NH4+ and by ABA. Our data indicate that OsSAPK9 interacts with OsbZIP20, and can phosphorylate OsbZIP20 and activate its function. When OsSAPK9 or OsbZIP20 are knocked out in rice, ABA-mediated antioxidant and GS/GOGAT activity enhancement under high-NH4+ stress disappear, and the two mutants are more sensitive to high-NH4+ stress compared with their wild types. Taken together, our results suggest that ABA plays a positive role in regulating the OsSAPK9-OsbZIP20 pathway in rice to increase tolerance to high-NH4+ stress.