| Abstrakt: |
To study the effects of different soil water conditions on pollen fertility and cottonseed yield, cotton plants were grown under different soil water conditions (normal water regime, waterlogging, mild drought, and medium drought) induced by different groundwater depths. Results showed that compared to the normal water regime, cottonseed yield decreased under waterlogging, mild drought, or medium drought. The mild drought had little effect on seed number per boll (SNB) and seed index, but waterlogging and medium drought had significantly negative effects on them. Weak pollen fertility might be the main reason for the decrease of SNB under waterlogging and medium drought, and the decreased pollen fertility was caused by the inhibited synthesis of starch and adenosine triphosphate in anthers. Waterlogging downregulated the activity of soluble starch synthases (SSSase) and the expression level of GhSSSase gene, but medium drought down-regulated SSSase and adenosine diphosphate-glucose pyrophosphorylase (AGPase) activities and the expression of GhAGPase and GhSSSase genes to impede starch synthesis. Moreover, waterlogging increased anther sucrose content by inhibiting acid invertase activity while medium drought increased the accumulation of sucrose content by decreasing sucrose synthetase activity. Both waterlogging and medium drought down-regulated the expression level of GhHXK gene, resulting in higher glucose content in anthers. Furthermore, increased O2− and H2O2 contents also adversely affected the pollen fertility, and this increase was attributed to lesser activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and down-regulated gene expression of Cu/Zn SOD, Mn SOD, POD, and CAT. Compared to the medium drought, proline content effectively increased under waterlogging, and a large decrease in SOD activity and Mn SOD gene expression was observed under waterlogging. Our findings suggest that both medium drought and waterlogging affected the carbohydrate and antioxidant metabolism to vitiate pollen viability, ultimately affecting cottonseed development, however, their effects on starch biosynthesis, sucrose decomposition, and antioxidant metabolism were not entirely uniform. These results will improve our knowledge and give us a direction on the mechanism of the tolerance to drought and waterlogging for cotton. [ABSTRACT FROM AUTHOR] |
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