College of Horticulture, Henan Agricultural University, Zhengzhou, 450002, PR China.
College of Horticulture, Henan Agricultural University, Zhengzhou, 450002, PR China.
Ecotoxicol Environ Saf. 2020 Apr 1;192:110285. doi: 10.1016/j.ecoenv.2020.110285.
Iron deficiency severely affects crop yield and quality. Gamma-aminobutyric acid (GABA) plays a vital role in plant responses to multifarious stresses. However, the role of GABA in Fe deficiency responses and the potential mechanisms remain largely unknown in cucumber. Here, we found that Fe deficiency raised the GABA levels in leaves and roots of cucumber. To probe the role of GABA in Fe deficiency, the seedlings were subjected to five levels of GABA concentrations (0, 5, 10, 20 and 40 mmol L) for 7 days under Fe deficiency. The results demonstrated that 20 mM GABA in alleviating the Fe deficiency-induced stress was the most effective. GABA pretreatment reduced the Fe deficiency-induced chlorosis and inhibition of photosynthesis and growth, and significantly enhanced the contents of iron in shoots and roots. Exogenous GABA significantly decreased the pH of nutrient solution and increased ferric-chelate reductase (FCR) activity induced by Fe deficiency and the transcript levels of Fe uptake-related genes HA1, FRO2 and IRT1 in roots. GABA also increased the content of auxin (IAA) and expression of auxin biosynthesis (YUC4), response (IAA1), and transport (PIN1) genes under Fe deficiency. Furthermore, exogenous the auxin transport inhibitor 1-naphthylphthalamic acid (NPA) application abolished the GABA-induced changes in Fe deficiency. In summary, we found that GABA improves tolerance to iron deficiency via an auxin-dependent mechanism in cucumber.
缺铁严重影响作物产量和品质。γ-氨基丁酸（GABA）在植物应对多种胁迫中起着至关重要的作用。然而，GABA 在铁缺乏响应中的作用及其潜在机制在黄瓜中仍知之甚少。在这里，我们发现缺铁会提高黄瓜叶片和根部的 GABA 水平。为了探究 GABA 在铁缺乏响应中的作用，将幼苗在铁缺乏条件下用 5 个 GABA 浓度（0、5、10、20 和 40 mmol L）处理 7 天。结果表明，20 mM GABA 缓解铁缺乏引起的胁迫最有效。GABA 预处理可减轻铁缺乏引起的黄化和光合作用及生长抑制，并显著提高地上部和根部的铁含量。外源 GABA 可显著降低营养液的 pH 值，提高铁缺乏诱导的铁螯合还原酶（FCR）活性和根中 Fe 吸收相关基因 HA1、FRO2 和 IRT1 的转录水平。GABA 还可增加铁缺乏下生长素（IAA）的含量和生长素合成（YUC4）、响应（IAA1）和运输（PIN1）基因的表达。此外，外源生长素运输抑制剂 1-萘基邻氨甲酰苯甲酸（NPA）的应用可消除 GABA 对铁缺乏的诱导变化。综上所述，我们发现 GABA 通过生长素依赖的机制提高了黄瓜对缺铁的耐受性。
