ESTIMATING WATER STRESS TOLERANCE GENE EXPRESSION IN COWPEA GENOTYPES

<p><strong>Background</strong>. This study examines cowpea (<em>Vigna unguiculata</em> L.) genotypes' water stress resistance molecular and physiological processes. It analyzes the association between <em>VuNCED1</em> and <em>P5CS</em> gene expression, antioxidant enzyme activities (SOD, CAT, APX, GR), and growth traits under different irrigation levels. <strong>Objective</strong>. Gene expression analysis and physiological responses to water stress will be used to assess the drought tolerance of Local, Ramshorn, and Black Crowder cowpea genotypes. <strong>Methodology</strong>. Split-plot within randomized complete block design was used in Babil Governorate, Iraq. Main plots had three irrigation levels (50 %, 65 %, and 80 % of available water depletion), which represent low, moderate, and high-water stress levels, respectively, to mimic field conditions in arid regions. While subplots had three cowpea genotypes. Important measurements were <em>VuNCED1</em> and <em>P5CS</em> gene expression, antioxidant enzyme activity (SOD, CAT, APX, GR), and growth-related characteristics. <strong>Results</strong>. <em>VuNCED1</em> and <em>P5CS</em> genes activated antioxidant defenses and maintained cellular homeostasis, thereby improving drought tolerance. Black Crowder and Ramshorn genotypes exhibited 30 % and 25 % higher gene expression levels, respectively, compared to the local genotype. Similarly, antioxidant enzyme activity was 35 % and 28 % greater in Black Crowder and Ramshorn genotypes, respectively, relative to the local genotype. Yield increases of 40 % and 25 % were observed in Black Crowder and Ramshorn genotypes, respectively, over the local genotype. Moreover, Black Crowder had 45 % more chlorophyll than Ramshorn and 30 % more than the local genotype, based on average measurements under identical conditions. <strong>Implications</strong>. Genetic and physiological modifications improve drought resilience, according to the study. The study reveals that Black Crowder and Ramshorn genotypes may be suitable for arid environments due to their better yields and stress resistance. <strong>Conclusion</strong>. Gene expression and physiological changes are crucial to crop water stress management, according to this study. The Black Crowder and Ramshorn genotypes are promising drought-resistant crop producers due to their flexibility and improved performance under low water conditions.</p>