Cuticular wax is known to play an important role in non-stomatal transpiration. However, support is lacking regarding the waxy phenotype for wheat breeding against drought. In this study, four wheat cultivars with different wax phenotypes (glaucous and non-glaucous types) were used to evaluate their responses to drought stress and impact on photosynthetic capability of wheat. Xinong 291 and HY 2912, with the glaucous trait, demonstrated higher diketone ratios and contents compared with Pubing 201 and Jinmai 47, which are the non-glaucous type. The cultivars HY 2912 and Jinmai 47 had 35% higher biomass than did Xinong 291 and Pubing 201 under severe drought condition. HY 2912 exhibited the highest wax load with or without drought stress. Jinmai 47 showed the highest ratio of alkane content. Among glaucous cultivars, drought-resistant HY 2912 may promote growth by decreasing water loss, increasing the diketone content, increasing the total wax load, and maintaining mesophyll and stomatal conductance. Among non-glaucous cultivars, drought-resistant Jinmai 47 may enhance growth via stomatal closure and increased mesophyll conductance and alkane ratios. The glaucous trait was not always associated with drought resistance, and correlation analysis revealed that the diketone ratio was positively related to the intercellular CO2 concentration. These results suggest that the mechanism of drought resistance in wheat is systematically regulated by wax alteration, stomatal conductance and mesophyll conductance. Therefore, wax content and composition as well as mesophyll and stomatal regulation should be considered in the breeding and selection of drought-resistant wheat cultivars.

中文翻译：

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在轻度和重度干旱条件下，含糖和无糖小麦品种的表皮蜡和光合能力的差异响应。

已知表皮蜡在非气孔蒸腾中起重要作用。然而，对于小麦抗旱育种的蜡质表型缺乏支持。在这项研究中，使用四个具有不同蜡表型（无糖和无糖类型）的小麦品种来评估其对干旱胁迫的响应以及对小麦光合能力的影响。西贡291和HY 2912具有白质性状，与非白质的Pubing 201和Jinmai 47相比，显示出更高的二酮比率和含量。在严重干旱条件下，HY 2912和Jinmai 47品种的生物量比Xinong 291和Pubing 201的生物量高35％。HY 2912在有或没有干旱胁迫下均表现出最高的蜡载量。金麦47的烷烃含量比例最高。在白垩纪品种中，抗旱的HY 2912可以通过减少水分流失，增加二酮含量，增加蜡的总含量以及保持叶肉和气孔导度来促进生长。在非无光栽培品种中，抗旱的金麦47可能通过气孔关闭和提高叶肉电导率和烷烃比来促进生长。白质性状并不总是与抗旱性相关，相关分析表明，二酮比与细胞间CO2浓度呈正相关。这些结果表明，小麦的抗旱机制是由蜡质变化，气孔导度和叶肉导度系统调节的。所以，