دراسات بيولوجية لبعض أنواع العائلة المالفية في المملكة العربية السعودية

Abstract

The current work includes taxonomic studies on four tribes of the Malvaceae in the Kingdom of Saudi Arabia, which are the Gossypieae, Hibiscieae, Malveae and Sideae tribes. The study was based on the available and preserved plant materials in the herbaria of King Saud University, Umm al-Qura'a University and the National herbarium in the Ministry of Agriculture as well as on field materials intensive in all parts of the Kingdom of Saudi Arabia. The study depends on six main chapters, starting with a general introduction. The general chapter dealt with a historical overview, geographical distribution, and the economic importance of plants of this family, as well as presenting the main objectives of the study. The second chapter dealt with a taxonomic review of plant species based on morphological characteristics as well as an evaluation of the most important taxonomic characteristics that were used. The results show that there are 22 species, representing 8 genera, belong to four tribes. The third chapter deals with the study of the morphology of pollen grains using an light microscope and an Scanning electronic microscope. The study showed that the pollen grains follow the tribes of Gossypieae, Hibiscieae, Malveae and Sideae, vary in shape from Prolate spheroidal to Oblate spheroidal. More than one pollen pattern was identified based on surface sculpturing. The study of the morphology of pollen grains provide high taxonomic differences to distinguish between species that are similar in outward appearance in the same tribe such as Abutilon. The fourth chapter of this study deals with the study of seed surfaces using light and scanning electron microscope. Macro- and micromorphological characters of the seeds are presented, including seed shape, color, size, hairs, surface pattern, epidermal cell shape, anticlinal boundaries, and periclinal cell wall. Seed character analysis offered useful data for evaluating the taxonomy of the Malvoideae. The study proved that the characteristics of epidermal cells have a high taxonomic value, especially with regard to the patterns of these cells, the nature of the walls separating them, and the characteristics of their external walls. These characters also showed the taxonomic importance of differentiating between the plant species under study at the level of genera and species. A key was made to differentiate the species based on these characters. The fifth chapter of this study examined the anatomical morphological characteristics of studied species, including stem, petiole and leaf. The results showed that some similar diagnostic characteristics have large taxonomic values and are used in turn to analyze the evolutionary relationships between the studied species such as vascular bundles, secondary vascular tissues, epidermal cells, cortex and mesophyll in the leaf and crystals. Anatomical features were used to prepare the key to identifying the species. The sixth chapter of this study deals with genetic investigation and genetic analyzes of the studied taxa. Ten Start Codon Targeted (SCoT) and five Inter Simple Sequence Repeats DNA (ISSR) primers created 138 polymorphic amplified fragments, which pointed to a comparatively high level of genetic difference in Malvoideae. SCoT markers exposed a higher level of polymorphism (89 bands) than ISSR (49 bands). The comparison of SCoT and ISSR based dendrograms revealed significantly similar grouping patterns of genotypes. Five clusters and clades were documented within Malvoideae, which generally verified traditional groupings with a few exceptions.