Piao Lin, Wang Yong, Liu Xiaoming, Sun Guangyan, Zhang Shiyu, Yan Junyao, Chen Yang, Meng Yao, Li Ming, Gu Wanrong
College of Agriculture, Northeast Agricultural University, Harbin, China.
Maize Research Institute, Heilongjiang Academy of Agricultural Sciences, Harbin, China.
Front Plant Sci. 2022 Sep 8;13:993675. doi: 10.3389/fpls.2022.993675. eCollection 2022.
Cadmium (Cd) stress is one of the principal abiotic stresses that inhibit maize growth. The research was to explore (hemin chloride) Hemin (100 μmol L) on photosynthesis, ascorbic acid (AsA)-glutathione (GSH) cycle system, and polyamine metabolism of maize under Cd stress (85 mg L) using nutrient solution hydroponics, with Tiannong 9 (Cd tolerant) and Fenghe 6 (Cd sensitive) as experimental materials. The results showed that Hemin can increase leaf photosynthetic pigment content and ameliorate the ratio of Chlorophyll a/chlorophyll b (/) under Cd stress. The values of ribose 1, 5-diphosphate carboxylase/oxygenase (RuBPcase) and phosphoenolpyruvate carboxylase (PEPCase), and total xanthophyll cycle pool [(violoxanthin (V), antiflavin (A) and zeaxanthin (Z)] increased, which enhancing xanthophyll cycle (DEPS) de-epoxidation, and alleviating stomatal and non-stomatal limitation of leaf photosynthesis. Hemin significantly increased net photosynthetic rate ( ), stomatal conductance ( ), transpiration rate ( ), photochemical quenching coefficient (), maximum photochemical efficiency ( ), and electron transfer rate (), which contributed to the improvement of the PSII photosynthetic system. Compared with Cd stress, Hemin can reduce thiobartolic acid reactant (TBARS) content, superoxide anion radical (O ) production rate, hydrogen peroxide (HO) accumulation, and the extent of electrolyte leakage (EL); decreased the level of malondialdehyde (MDA) content and increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); slowed the decrease in dehydroascorbic acid reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activity and the increase in glutathione reductase (GR) and ascorbate peroxidase (APX) activity in leaves; promoted the increase in AsA and GSH content, decreased dehydroascorbic acid (DHA) and oxidized glutathione (GSSG), and increased AsA/DHA and GSH/GSSG ratios under Cd stress. Hemin promoted the increase of conjugated and bound polyamine content, and the conversion process speed of free putrescine (Put) to free spermine (Spm) and spermidine (Spd) in maize; decreased polyamine oxidase (PAO) activity and increased diamine oxidase (DAO), arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) enzyme activities in leaves under Cd stress.
镉（Cd）胁迫是抑制玉米生长的主要非生物胁迫之一。本研究采用营养液水培法，以耐镉品种天农9和镉敏感品种丰禾6为试验材料，探讨氯化血红素（Hemin，100 μmol·L）对镉胁迫（85 mg·L）下玉米光合作用、抗坏血酸（AsA）-谷胱甘肽（GSH）循环系统及多胺代谢的影响。结果表明，Hemin能增加镉胁迫下叶片光合色素含量，改善叶绿素a/叶绿素b比值（/）。核酮糖-1,5-二磷酸羧化酶/加氧酶（RuBPcase）和磷酸烯醇式丙酮酸羧化酶（PEPCase）活性以及总叶黄素循环库[紫黄质（V）、花药黄质（A）和玉米黄质（Z）]值升高，增强了叶黄素循环（DEPS）脱环氧化作用，减轻了叶片光合作用的气孔和非气孔限制。Hemin显著提高了净光合速率（ ）、气孔导度（ ）、蒸腾速率（ ）、光化学猝灭系数（）、最大光化学效率（ ）和电子传递速率（），有助于改善PSII光合系统。与镉胁迫相比，Hemin可降低硫代巴比妥酸反应物（TBARS）含量、超氧阴离子自由基（O ）产生速率、过氧化氢（H₂O₂）积累量和电解质渗漏率（EL）；降低丙二醛（MDA）含量水平，提高超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）活性；减缓叶片中脱氢抗坏血酸还原酶（DHAR）和单脱氢抗坏血酸还原酶（MDHAR）活性的下降以及谷胱甘肽还原酶（GR）和抗坏血酸过氧化物酶（APX）活性的升高；促进镉胁迫下AsA和GSH含量增加，降低脱氢抗坏血酸（DHA）和氧化型谷胱甘肽（GSSG）含量，提高AsA/DHA和GSH/GSSG比值。Hemin促进了玉米中结合态和束缚态多胺含量的增加以及游离腐胺（Put）向游离精胺（Spm）和亚精胺（Spd）的转化过程速度；降低了镉胁迫下叶片中多胺氧化酶（PAO）活性，提高了二胺氧化酶（DAO）、精氨酸脱羧酶（ADC）、鸟氨酸脱羧酶（ODC）和S-腺苷甲硫氨酸脱羧酶（SAMDC）的酶活性。
