Molecular and biochemical studies for heat tolerance on four cotton genotypes

Abstract

The impact of heat stress on the morphological, biochemical and molecular studies was examined in four cotton genotypes (Gossypium hirsutum L.) grown at control (30°C) and heat stress (40°C). Significant reduction appeared in morphological criteria (shoot length, root length, fresh and dry weight of seedlings), photosynthetic pigments, proline and total soluble sugars in two cotton genotypes (Giza 80 and Giza 90). On the other hand, the same criteria significantly increased under heat stress in the two others cotton genotypes (Giza 85 and Giza 92) when compared with control plants. Meanwhile, all treatments caused variations in number, intensity and/or density of SDS electrophoretic bands of proteins. In addition, electrophoretic studies of isozymes activities showed variation in the intensities and densities under heat stress treatments in four cotton genotypes. The variation in DNA profile was detected by RAPD-PCR technique. The results of RAPD analysis using the five primers indicated the appearance of DNA polymorphic bands in all cotton genotypes. It is concluded that two cotton genotypes are tolerant genotypes (Giza 85 and Giza 92) and can be introduced in breeding programs.