Salinity and drought are the two most important and frequently co-occurring abiotic factors. A greenhouse pot experiment was carried out on two contrasting wheat genotypes (Jimai22, salt tolerant; Yangmai20, salt sensitive) to analyze the effect of drought (4% soil moisture content, D) and salinity (100 mM NaCl, S) either individually or combined on secondary metabolism-related enzyme activities and osmolytes. Results showed that drought, salinity and their combination (D+S) caused increases in phenylalanine ammonialyase (PAL, EC 4.3.1.24) activities compared with controls with a greater enhancement in Jimai22 than Yangmai20. Polyphenol peroxidase (PPO, EC 1.14.18.1) and shikimate dehydrogenase (SKDH, EC 1.1.1.25) activities increased more in Jimai22 both under salinity alone and D+S stresses. The D+S combination increased cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195) activity and glycine betaine (GB) under both 10 and 4% soil moisture contents (SMC), and elevated abscisic acid (ABA), indole-3-acetic acid (IAA) and flavonoid contents at 4% SMC in Jimai22, contents of the compounds remained unchanged in Yangmai20. The treatment with salinity alone at both SMCs significantly increased callose and flavonoid contents in Jimai22 more than in Yangmai20, as compared to controls. In addition, the total phenol content at 4% SMC increased in the salt tolerant genotype more. Moreover, total tocopherol under salinity alone and D+S at 4% SMC and chitinase activity under salinity at both SMC remarkably increased in Jimai22 while non-significant change observed in Yangmai20. Also, the expression of genes related to secondary metabolism (PAL, PPO, CAD, SKDH, and GB) was more induced in Jimai22 than Yangmai20 under D+S, and lower accumulation of H2 O2 and O2 - also occurred. Our findings suggest that high tolerance to D+S stress in Jimai22 was closely related to enhanced secondary metabolism related enzyme activities and osmolytes such as PAL, CAD, PPO, SKDH, GB, total tocopherol, callose, plant hormones and their transcript level, which may beneficial to lower the reactive oxygen species (ROS) accumulation. This article is protected by copyright. All rights reserved.

中文翻译：

---

次生代谢相关酶活性的基因型差异及其相关基因表达模式、渗透物和植物激素

盐度和干旱是两个最重要且经常同时发生的非生物因素。对两种不同的小麦基因型（吉麦 22，耐盐；扬麦 20，盐敏感）进行温室盆栽试验，以单独或分析干旱（4% 土壤水分含量，D）和盐度（100 mM NaCl，S）的影响结合次级代谢相关的酶活性和渗透物。结果表明，与对照相比，干旱、盐度及其组合 (D+S) 导致苯丙氨酸解氨酶 (PAL, EC 4.3.1.24) 活性增加，其中济麦 22 的增强大于扬麦 20。多酚过氧化物酶 (PPO, EC 1.14.18.1) 和莽草酸脱氢酶 (SKDH, EC 1.1.1.25) 活性在 Jimai22 中增加更多，无论是在单独的盐度还是 D+S 胁迫下。D+S 组合在 10% 和 4% 的土壤水分含量 (SMC) 下增加肉桂醇脱氢酶 (CAD, EC 1.1.1.195) 活性和甘氨酸甜菜碱 (GB)，并提高脱落酸 (ABA)、吲哚-3-乙酸在济麦 22 中 4% SMC 的酸 (IAA) 和黄酮类化合物含量，洋麦 20 中化合物的含量保持不变。与对照相比，在两个 SMC 中单独用盐处理显着增加了 Jimai22 中的胼胝质和类黄酮含量。此外，在耐盐基因型中，4% SMC 的总酚含量增加更多。此外，仅盐度下的总生育酚和 4% SMC 的 D+S 和盐度下两种 SMC 的几丁质酶活性在济麦 22 中显着增加，而在扬麦 20 中观察到无显着变化。此外，与次级代谢相关的基因（PAL、PPO、CAD、SKDH 和 GB) 在 D+S 条件下在济麦 22 中比扬麦 20 中更多地被诱导，并且也发生了较低的 H2 O2 和 O2 - 积累。我们的研究结果表明，济麦22对D+S胁迫的高耐受性与增强的次级代谢相关酶活性和渗透物如PAL、CAD、PPO、SKDH、GB、总生育酚、胼胝质、植物激素及其转录水平密切相关。可能有利于降低活性氧 (ROS) 的积累。本文受版权保护。版权所有。总生育酚、胼胝质、植物激素及其转录水平，这可能有利于降低活性氧 (ROS) 的积累。本文受版权保护。版权所有。总生育酚、胼胝质、植物激素及其转录水平，这可能有利于降低活性氧 (ROS) 的积累。本文受版权保护。版权所有。