Drought-induced responses in maize under different vapor pressure deficit conditions

Authors: Mura, Jyostna; Reddy, Vangimalla; Timlin, Dennis

Submitted to: Plant, Cell & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2022
Publication Date: 10/19/2022
Citation: Mura, J.D., Reddy, V., Timlin, D.J. 2022. Drought-induced responses in maize under different vapor pressure deficit conditions. Plant, Cell & Environment. 11:2771. https://doi.org/10.3390/plants11202771.
DOI: https://doi.org/10.3390/plants11202771

Interpretive Summary: Drought and dry air are the primary cause of low yields worldwide. Understanding the physiological, biochemical, and molecular responses to these adverse conditions will help to improve the drought tolerance in corn and other crops. The study was conducted by imposing three levels of drought (well-irrigated, moderate stress, and severe stress) at three atmospheric air (humid, medium, and dry air) conditions. We observed the adverse effects of both drought and dry air on leaf development and photosynthesis in maize. Plants acclimated to the abiotic stresses by adjusting enzyme activities and gene expression levels, especially genes regulating abscisic acid. The findings of this study are useful in understanding the drought response mechanisms in maize and development of drought-tolerant varieties in maize breeding programs.

Technical Abstract: Drought is a significant factor limiting maize growth and productivity. Water stress in plants depends on the soil water level and the evaporative demand. Physiological, biochemical, and molecular responses of maize to different soil water content under three different evaporative demand conditions were tested in controlled growth chambers. In this study, the physiological response of maize was analyzed under low (~1.00 kPa vapor pressure deficit (VPD), medium (~2.2 kPa), and high (~4.00 kPa) evaporative demand conditions at three different soil water content (SWC); well-watered, 45% and 35% SWC. Plants grown at 35% SWC under high VPD had significant (P<0.01) low leaf wt., leaf area, and leaf number than low evaporative demand condition. Plants under low, medium, and high VPD with drought stress (45% and 35% SWC) showed a 30 to 60% reduction in their leaf area compared to well-watered plants. Along with leaf traits, other physiological parameters such as photosynthesis, stomatal conductance, and water use efficiency showed significant differences (P<0.01) among treatments, with the highest reduction at 35% SWC and high VPD. The percentage of reduction in photosynthesis across VPD and SWC treatments ranged from 9 to 26%. A significant effect of both drought and VPD was observed with on the levels of C4 enzymes and transcription factors, with increased levels as the stress levels improved. The transcription factors primarily related to ABA synthesis were upregulated under drought, which might be related to high ABA levels. In summary, severe drought levels coupled with dry air environments (high VPD) had shown a significant decrease in leaf growth, stomatal conductance, and photosynthesis by modifying enzymes, ABA, and transcription factor levels.