Low temperature combined with low light (LL) stress is a notable factor limiting the yield and economic viability of pepper cultivation in Northwest China. Glycine betaine (GB), an antioxidant and osmotic regulator, positively regulates abiotic stress in plants. However, few investigations have been conducted to determine whether GB modulates LL stress by involving changes in photosynthesis and m6A methylation. Herein, pepper seedlings were pre-treated with 20 mmol L–1 GB and 60 µmol L–1 3-deazaneplanocin A hydrochloride (DAA) under LL stress of 10/5°C and 100 µmol m–2 s–1 to investigate the regulatory mechanism of GB-induced tolerance to LL. Results indicated that the pre-treatment with GB alleviated the growth inhibition and photoinhibition caused by LL stress. It considerably increased the photosynthetic capacity and chlorophyll content by protecting the photosynthetic electron-transport system, increasing the stomatal aperture and activity of enzymes in the Calvin cycle and upregulating the expression of the genes encoding chloroplast proteins. Additionally, GB reduced sugar content, regulated phytohormones, upregulated the expression levels of CaCBF1A, CaCBF1B, and CaF-BOX, and downregulated the expression levels of CaMTA, CaMTC, and CaFIP37 (m6A methylases). Conversely, it upregulated the expression levels of CaALKBH1 and CaALKBH6 (m6A demethylases). However, the addition of DAA worsened the damage caused by LL, yet when sprayed simultaneously with DAA and GB, this inhibition was reversed. These findings indicated that GB provided LL tolerance to pepper seedlings possibly by improving plant growth, enhancing photosynthetic properties, regulating sugar hormone metabolism, and mediating m6A methylase.

中文翻译：

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甘氨酸甜菜碱通过提高光合能力和调节相关基因相关的 m6A 甲基化酶来缓解辣椒 （Capsicum annuum L.） 的低温结合低光胁迫


低温结合弱光 （LL） 胁迫是限制西北地区辣椒种植产量和经济可行性的重要因素。甘氨酸甜菜碱 （GB） 是一种抗氧化剂和渗透调节剂，可积极调节植物的非生物胁迫。然而，很少有研究来确定 GB 是否通过涉及光合作用和 m6A 甲基化的变化来调节 LL 应激。本文以辣椒幼苗为研究对象，在 10/5°C 和 100 μmol m–2 s–1 的 LL 胁迫下，用 20 mmol L–1 GB 和 60 μmol L–1 3-deazaneplanocin A hydrochloride （DAA） 预处理辣椒幼苗，探讨 GB 诱导的 LL 耐受的调控机制。结果表明，GB 预处理减轻了 LL 胁迫引起的生长抑制和光抑制。它通过保护光合电子传输系统、增加加尔文循环中酶的气孔孔径和活性以及上调编码叶绿体蛋白的基因的表达，大大增加了光合能力和叶绿素含量。此外，GB 降低了糖含量，调节植物激素，上调了 CaCBF1A 、 CaCBF1B 和 CaF-BOX 的表达水平，下调了 CaMTA 、 CaMTC 和 CaFIP37 （m6A 甲基化酶） 的表达水平。相反，它上调 CaALKBH1 和 CaALKBH6 （m6A 去甲基化酶） 的表达水平。然而，DAA 的添加加剧了 LL 造成的损伤，然而当与 DAA 和 GB 同时喷洒时，这种抑制作用被逆转。这些发现表明，GB 可能通过改善植物生长、增强光合特性、调节糖激素代谢和介导 m6A 甲基化酶来提供对辣椒幼苗的 LL 耐受性。