Ecological Distribution and Taxonomy of Opuntia sp. in Egypt, Based on Morphological Criteria and Molecular Genetic Structure

Abstract

One hundred five stands (10m X 10m) distributed within thirteen sites located at four governorates (Qalyubiya, Minufiya, Buhayrah andMarsa Matrouh)were surveyed in autumn and spring of 2015 and 2016 to study the floristic composition of associated flora with Opuntia populations, cladodes and fruits of 18 accessions were collected for taxonomical (based on morphological characteristics and molecular genetics) and ecological study, in addition 13 soil samples were collected. The taxonomic study based on the morphological characteristics classified the 18 accessions of Opuntia into two distinct species, Opuntia ficus indica which distributed in Delta governorates and Opuntia littoralis found in Wadi Maged, Marsa Matrouh, Costal Mediterranean region. In addition, Opuntia ficus indica separated to three phenotypes according to the fruit characteristics. Molecular genetic data by using RAPD and ISSR technique support this classification and it was recorded specific marker bands for Opuntia littoralis, Opuntia ficus indica bearing yellow fruits and Opuntia ficus indica bearing reddish fruits. Therefore, Opuntia ficus indica in this study classified to three genotypes. Flora of the study sites represented 81 species of the Egyptian flora where they are belonging to 72 genera and 30 families. Poaceae represented the most dominant plants associated with Opuntia communities, followed by Asteraceae, Chenopodiaceae, Brassicaceae and Fabaceae. The application of TWINSPAN on the cover estimates of 81 associated species recorded in the 105 sampled stands of PricklyPear, led to the recognition of 10 vegetation groups. Soil of Opuntia ficus indicapopulations mainly constructed from silt and clay (loamy soil), while that of O. littoralis is sandy.Soil of O, ficus indica has low pH, CaCO3, N and P but high EC, Organic matter, anions and cations than soil of O. littoralis. High concentrations of Fe, Zn and Mn were recorded in soils O. ficus indica but high concentrations of Cu, Co, Pb, Ni and Cd were recorded in soil of O. littoralis. All estimated heavy metals in soils of Opuntia were in allowable concentration according to World Health Organization (WHO). Growth traits of Opuntia trees and cladodes indicated high similarity among phenotypes of O. ficus indica but highly significant differed with O. littoralis. Orange fruits of O. ficus indica have the best quality in site 1 (Al Khanka Hospital) than other sites. O. littoralis fruits have thick skin which protects them from environmental conditions than O. ficus indica fruits. Concentration of N and P in cladodes of Opuntia species is higher enough to optimum production. Concentration of Fe and Zn in the cladodes and fruits of the studied taxa were in the allowable concentrations. Concentrations of Mn, Co, Pb and Cd recorded higher concentrations in cladodes and fruits of the three genotypes of O. ficus indica and O. littoralis than the allowable limits set by WHO. The three genotypes of O. ficus indica had high capability to bioaccumulate Pb, Cd, Co and Ni in their cladodes and high tendency to translocate them to fruits. High concentration of heavy metals in the cladodes and fruits has serious impact on humans and animals when consume them. On the other hand, they may be has important role in phytoremediation by extraction and bioaccumulation of heavy metals.

Key Words:Opuntiaficus indica – Opuntia littoralis – phenotypes – RABD – ISSR – Genotype - Floristic Diversity - Vegetation Analysis – TWINSPAN – Soil analysis – Heavy metals – Vegetative growth – Bioconcentration factors – Translocation factors