Cytological studies on unicellular origin pathway, early ordered cell division patterns and morphogenesis in indirect somatic embryogenesis of catharanthus roseus cell lines

El-Sheikh, M. A.; Abo-Elenein, H. E.

doi:10.21608/ajar.2023.316059

Cytological studies on unicellular origin pathway, early ordered cell division patterns and morphogenesis in indirect somatic embryogenesis of catharanthus roseus cell lines

Document Type : Original Article

Authors

M. A. El-Sheikh ¹
H. E. Abo-Elenein ²

¹ Plant Genetics Laboratory, Department of Botany, Agriculture, Al-azhar University, Naser city, Cairo, Egypt

² Plant physiology laboratory, Department of Botany, Agriculture, Al-azhar University, Naser city, Cairo, Egypt.

10.21608/ajar.2023.316059

Abstract

Unicellular Origin of the Madagascar periwinkle indirect somatic embryogenesis developmental pathway (ISEDP) were studied and the conformation of embryogenic stability potential of suspension culture cell lines as well. We investigated the ordered pattern of cell division and early histo-differentiation over time, using light microscope. The ontogenesis of indirect somatic embryogenesis of callus was first induced from hypocotyls of in vitro germinated seeds on Murashige and Skoog medium supplemented with 2,4-dichlorophenoxy acetic acid or in the (MS) basic medium amended with 1mg/L NAA and 1.5mg/L BA and characterized through cytological analysis of different phases of embryogenesis from the first cellular division to the last step of their development. Our investigation and observations based on basic smeared modified technique that enables us to conclude that: the onset and the ontogenesis of indirect somatic embryos developments (ISED) of C.roseus arise from one single embryogenic characterized cell that is very similar to zygotic cell, capable of complete proliferation through different ordered cell division patterns (e.g., transverse asymmetric division within the embryogenic cell; longitudinal division within apical cell; symmetric transverse division in suspensor cell and periclinal division to form protoderm in the outermost layer of the globular-stage), and complete their differentiation to form different morphogenetic developmental stages described: oblong-shape; heart-shape; torpedo-shape; elongated -shape "enlarged stage" and cotyledonary-shaped embryos. The morphogenesis, structure and other analogies details with the development of dicotyledon zygote are also emphasized. This finding is of considerable interest, significance, and the basic prerequisite before plant genetic improvements based genetic transformation; somatic hybridization and mutation breeding to enhance TIA yield can be employed. This study is to our knowledge the first works on Catharanthus roseus somatic embryogenesis clearly presenting and describing unicellular origin pathway; sequential events in early and advanced developmental stages including oblong and elongated transition stages which have rarely been reported in the majority of plant species.

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