Environmental changes derived from global warming and human activities increase the intensity and frequency of stressful conditions for plants. Multiple abiotic factors acting simultaneously enhance stress pressure and drastically reduce plant growth, yield and survival. Stress combination causes a specific stress situation that induces a particular plant response different to the sum of responses to the individual stresses. Here, by comparing transcriptomic and proteomic profiles to different abiotic stress combinations in two citrus genotypes, Carrizo citrange (Citrus sinensis × Poncirus trifoliata) and Cleopatra mandarin (Citrus reshni), with contrasting tolerance to different abiotic stresses, we revealed key responses to the triple combination of heat stress, high irradiance and drought. The specific transcriptomic response to this stress combination in Carrizo was directed to regulate RNA metabolic pathways and translation processes, potentially conferring an advantage with respect to Cleopatra. In addition, we found endoplasmic reticulum stress response as common to all individual and combined stress conditions in both genotypes and identified the accumulation of specific groups of heat shock proteins (HSPs), such as small HSPs and HSP70s, and regulators of the unfolded protein response (UPR), BiP2 and PDIL2-2, as possible factors involved in citrus tolerance to triple stress combination. Taken together, our findings provide new insights into the acclimation process of citrus plants to multiple stress combination, necessary for increasing crop tolerance to the changing climatic conditions.

中文翻译：

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柑橘的组学分析揭示了 RNA 翻译途径和 UPR 调节因子在耐受干旱、高辐照和热胁迫方面的可能作用

全球变暖和人类活动引起的环境变化增加了植物面临压力的强度和频率。多种非生物因素同时作用会增强胁迫压力，并大大降低植物的生长、产量和存活率。胁迫组合会导致特定的胁迫情况，从而引起特定的植物反应，该反应不同于对各个胁迫的反应总和。在这里，通过比较两种柑橘基因型卡里佐柑橘（Citrus sinensis × Poncirus trifoliata）和 Cleopatra mandarin（Citrus reshni）中不同非生物胁迫组合的转录组和蛋白质组谱，以及对不同非生物胁迫的耐受性对比，我们揭示了对三重胁迫的关键反应热应激、高辐照度和干旱的结合。Carrizo 对这种应激组合的特定转录组反应旨在调节 RNA 代谢途径和翻译过程，这可能赋予 Cleopatra 相对于 Cleopatra 的优势。此外，我们发现内质网应激反应对于两种基因型的所有个体和组合应激条件都是常见的，并确定了特定组的热休克蛋白（HSP）的积累，例如小HSP和HSP70，以及未折叠蛋白反应的调节因子(UPR)、BiP2 和 PDIL2-2，作为柑橘对三重胁迫组合的耐受性的可能因素。总而言之，我们的研究结果为柑橘植物适应多种胁迫组合的过程提供了新的见解，这对于提高作物对不断变化的气候条件的耐受性是必要的。