الملخص
This study is an attempt to study genetic diversity among maize (Zea mays L.) cultivars grown in Saudi Arabia and their response to drought stress. It aims also to identify maize cultivars with high nutritional value and stress resistant which help to improve the cultivation of maize cultivars in Saudi Arabia. Eight different maize (Zea mays L.) cultivars grown in Saudi Arabia were selected for this study. Maize seeds were germinated in the greenhouse and subjected to drought stress. Morphological changes were recorded in terms of leaf area, plant height, shoot dry weight, root dry weight and root/shoot ratio. Physiological measurements such as leaf diffusive resistance, relative water content and proline content were also recorded. SDS-PAGE was carried out to study the effect of drought on the electrophoretic profile of total soluble proteins. Molecular analysis using RAPD-PCR was carried out to study the genetic diversity among maize cultivars. Different zein fractions were extracted from maize seeds and analyzed using SDS-PAGE. In addition, specific PCR reactions were conducted to characterize zein encoding genes in maize cultivars. RAPD-PCR analysis revealed the separation of Hendi maize cultivar from other cultivars under study indicating different genetic origin. This was supported by the absence of the methionine-rich 10 kDa delta zein polypeptide and its encoding gene in this cultivar. Moreover, drought stress showed dramatic effect on Hendi cultivar. It was very sensitive to drought stress with respect to leaf area, proline content and electrophoretic pattern of total soluble proteins. Hendi cultivar indicated the disappearance of seven proteins (65, 55, 40, 32, 29, 28 and 22 kDa) under drought stress, which could be correlated with a considerable increase in proline content. In this situation, it is not recommended to use this cultivar in cultivation programs in Saudi...
