Effects of water deficit on physiology and biochemistry of seedlings of different wheat varieties and the alleviation effect of exogenous application of 5-aminolevulinic acid
摘要
<p id="C3">Drought stress happens frequently in Huang-Huai winter wheat planted area, causing severe injury on photosynthetic apparatus of wheat seedlings. To characterize the traits of photosynthetic physiology in different wheat cultivars in response to water deficit, the newly in-lab cultivated Zhengmai 1860, as well as Bainong 207 and Zhoumai 18 were used as materials in this study. We explored the effects of water deficit on photosynthetic traits, antioxidant enzyme activities, and related gene transcription of seedlings in different cultivars, as well as the drought alleviation effect of exogenous application of 5-aminolevulinic acid (ALA). The results were as follows: Zhengmai 1860 had comparatively higher root dry weight and root shoot ratio than the other two cultivars under drought stress. Compared to Zhoumai 18, the drought resistant cultivars (Zhengmai 1860 and Bainong 207) had lower reduction in chlorophyll content and increased MDA content, enhanced the activities of SOD and CAT, and lowered reductions in chlorophyll fluorescence parameters and the photosynthetic parameters. Meanwhile, water deficit obviously improved the transcriptions of antioxidant enzyme-encoded genes <italic>CAT</italic>, <italic>SOD-Cu/Zn</italic>, <italic>MnSO</italic>, and<italic> FeSOD</italic>, which showed a correlation between the increasing level with the drought resistant ability. The exogenous pretreatment of ALA further enhanced the activities of SOD and CAT to lower the damage to membrane lipid peroxidation by inducing the transcriptions of <italic>CAT</italic>, <italic>SOD-Cu/Zn</italic>, and <italic>MnSOD</italic>. ATPase activity was also increased to alleviate water deficit on the damage to photosynthetic physiology. Moreover, we found for the first time that the transcriptional maintenance of chloroplast photosynthetic apparatus related <italic>psb28</italic> gene had a correlation with the drought resistance between different wheat cultivars, which was also signi