Drought stress and tropical maize: QTLs for leaf greenness, plant senescence, and root capacitance

Few studies have reported on the flowering time mechanism of tropical maize under short-day conditions. Drought, another important factor that affects flowering time, has been reported to delay the silking date in tropical maize. However, due to the lack of genetic information related to flowering in maize, the mechanism by which drought delays flowering is unclear. To further understand this process, we analyzed drought-responsive genes using RNA sequencing and identified genes related to flowering time, including contigs from de novo assembly. The results revealed changes in the expression of flowering-time genes, including INDETERMINATE1 (ID1), Heading date 3a (Hd3a), CONSTANS-like genes, and ZEA MAYS CENTRORADIALES8 (ZCN8), which are known to be crucial factors in flowering. In particular, Hd3a, CONZ1, and ZCN8, which have been reported to accelerate flowering under short-day conditions, were downregulated by drought stress. Changes in gene expression appear to play an important role in changes in flowering time under drought. These expression profiles will help to further understand the flowering-time genes of tropical maize and the delayed flowering time resulting from drought.

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Short-term physiological responses to drought stress in seedling of tropical and temperate maize (Zea mays L.) cultivars

Journal of Biological Research - Bollettino della Società Italiana di Biologia Sperimentale ◽

10.4081/jbr.2019.8015 ◽

2019 ◽

Vol 92 (1) ◽

Author(s):

Pu Zhao ◽

Jin Wang ◽

Niran Juntawong ◽

Chokechai Aekatasanawan ◽

Prasart Kermanee ◽

...

Keyword(s):

Zea Mays ◽

Drought Stress ◽

Drought Resistance ◽

Zea Mays L ◽

Physiological Responses ◽

Physiological Parameter ◽

Tropical Maize ◽

Gas Exchange Parameters ◽

Maize Hybrids ◽

Antioxidase Activity

Understanding of the response of tropical and temperate maize (Zea mays L.) to drought is the first step for tolerant temperate maize improvement. Eight maize hybrids were used to investigate physiology responses under drought stress, four of them were tropical maize and the others were temperate maize. Results showed that there were different drought tolerances but similar trends in both tropical maize and temperate maize. Gas exchange parameters revealed different strategies of maize under the stress. In our study, most of the temperate hybrids maintained open stomata to keep a higher photosynthesis rate at the beginning of stress, while the other hybrids decreased stomatal conductance. Compared to temperate maize, the tropical maize had higher antioxidase activity and greater physiological parameter variation among hybrids. KS5731 and ZD309 had stronger drought resistance among tropical and temperate maize hybrids separately. Tolerant hybrids maintained active photosynthesis, have higher osmotic adjustment ability and antioxidase activities but lower malonaldehyde content than the sensitive ones. Our results led to a better understanding of the physiological responses of tropical and temperate maize plants to drought stress and may provide an insight of breeding for drought resistance in maize.

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