Hassan Abdelrahim H A, Ahmed Enas Shaban, Sheteiwy Mohamed S, Alhaj Hamoud Yousef, Okla Mohammad K, AlGarawi Amal Mohamed, Maridueña-Zavala Maria Gabriela, Alaraidh Ibrahim A, Reyad Ahmed M, Abdelgawad Hamada
School of Biotechnology, Nile University, Giza, Egypt.
Department of Food Safety and Technology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef, Egypt.
Front Plant Sci. 2024 Dec 19;15:1500894. doi: 10.3389/fpls.2024.1500894. eCollection 2024.
Heat stress caused by global warming adversely affects wheat yield through declining most nutritional quality attributes in grains, excluding grain protein content.
This research investigated the biochemical, physiological, and antioxidant responses of wheat plants under heat stress, focusing on the role of plant growth-promoting bacteria ( sp.). Two wheat genotypes were studied: one heat-sensitive and one heat-tolerant, examining their responses to heat stress with and without bacterial inoculation.
Under heat stress, the sensitive cultivar experienced significant reductions in photosynthesis rate, chlorophyll content, and RuBisCO activity (57-61%), while the tolerant cultivar had milder reductions (24-28%). sp. treatment notably improved these parameters in the sensitive cultivar (+48-78%), resulting in a substantial increase in biomass production (+43-53%), which was not seen in the tolerant cultivar. Additionally, oxidative stress markers (HO and MDA) were elevated more in the sensitive cultivar (82% and 90% higher) compared to the tolerant one. sp. treatment effectively reduced these markers in the sensitive cultivar (-28% and -27%). Enhanced activity of antioxidant enzymes and ASC-GSH pathway enzymes was particularly evident in sp.-treated sensitive plants. Carbohydrate metabolism shifted, with increased soluble sugars and significant rises in sucrose content in sp.-treated plants under stress.
The higher soluble sugar levels facilitated amino acid synthesis, contributing to biosynthesis of secondary metabolites, including flavonoids, polyphenols, and anthocyanins. This was reflected in increased activity of phenylalanine ammonia-lyase, cinnamate (CA) 4-hydroxylase, and chalcone synthase enzymes, indicating the activation of phenylpropanoid pathways. Overall, the findings suggest that sp. can mitigate heat stress effects by enhancing photosynthetic efficiency, antioxidant defense, and metabolic adaptations in heat-sensitive wheat cultivars.
全球变暖导致的热应激通过降低谷物中除蛋白质含量外的大多数营养品质属性，对小麦产量产生不利影响。
本研究调查了热应激下小麦植株的生化、生理和抗氧化反应，重点关注植物促生细菌（ 种）的作用。研究了两个小麦基因型：一个热敏型和一个耐热型，考察它们在接种和未接种细菌情况下对热应激的反应。
在热应激下，敏感品种的光合速率、叶绿素含量和核酮糖-1,5-二磷酸羧化酶（RuBisCO）活性显著降低（57 - 61%），而耐受品种的降低幅度较小（24 - 28%）。 种处理显著改善了敏感品种的这些参数（提高了48 - 78%），使生物量产量大幅增加（增加了43 - 53%），而耐受品种未出现这种情况。此外，与耐受品种相比，敏感品种的氧化应激标志物（过氧化氢和丙二醛）升高幅度更大（分别高出82%和90%）。 种处理有效降低了敏感品种中的这些标志物（分别降低28%和27%）。抗氧化酶和抗坏血酸-谷胱甘肽（ASC-GSH）途径酶的活性增强在 种处理的敏感植株中尤为明显。碳水化合物代谢发生变化，应激条件下 种处理的植株中可溶性糖增加，蔗糖含量显著上升。
较高的可溶性糖水平促进了氨基酸合成，有助于包括黄酮类、多酚类和花青素在内的次生代谢物的生物合成。这体现在苯丙氨酸解氨酶、肉桂酸（CA）4-羟化酶和查尔酮合酶的活性增加上，表明苯丙烷途径被激活。总体而言，研究结果表明 种可通过提高热敏感小麦品种的光合效率、抗氧化防御和代谢适应性来减轻热应激影响。
