Usage of DNases and NDP kinases as qualitative markers to discriminate apomictic embryos of Poncirus trifoliata L. and Citrus aurantium L. rootstocks

Abstract

The aim of the present work was to study the qualitative changes of DNases and NDP kinases of Poncirus trifoliata L. and Citrus aurantium L. rootstocks between apomictic pairs of cotyledons of different developmental stage (large and smaller pair) in mature seeds. In nucleolytic analysis of P. trifoliata, differences were observed between large and small pairs of cotyledons. Specifically, in small pairs two DNase isoforms were formed, while in the large pairs, an additional isoform appeared. In C. aurantium, four DNase isoforms were present. The first isoform appeared in all treatments, and the three other isoforms only in large pair extracts. In both P. trifoliata and C. aurantium SDS-PAGE, large pair of cotyledons showed peptide bands more intense compared to pairs of small cotyledons. When cotyledonary extract was incubated in the presence of different metals, different number and intensity of peptide bands was appeared. From TLC autoradiography, it was found that all phosphorylated bands were catalytic subunits of NDP kinases, but showed different specificity towards substrates (phosphorylated NDPs). DNases and NDP kinase activity depend on the developmental stage of nucellar embryos’ cotyledons of P. trifoliata and C. aurantium and they could be used as an efficient and precise scientific method for indicating it.