Cytogenetic Characterization Of Cissus Quadrangularis L.

Cissus quadrangularis L.is a perennial climbing plant in the grape family(Vitaceae)with succulent angular stems being endemic in Africa and with worldwide distribution.The plant grows in arid and semi-arid areas of Africa thriving in the African savanna.The plant has a broad spectrum of application in both human and animal medicine in the old era as well as in the current times.Extracts from whole plants as well from the tissues have been used for medicinal purposes in both human and animal medicine.The stem of C.quadrangularis L.has also been identified for their potential utilization in the production of natural fibers.Limited information including cytogenetic data about this species is available despite its wide distribution and the potential utilization.In this study,the genome size and the number of the chromosome were determined in C.quadrangularis L.In addition,the characters of repetitive elements were also analyzed by using next-generation sequencing(NGS)data and biointormatic analysis.The main results that were obtained were as follows;1.Flow cytometry was used to evaluate the genome size of C.q,adrangularis L.Radish was used as an internal standard.Fluorescent histograms were obtained with acceptable quality(CV-values<5).Based on the peak reading from radish with known genome size,the genome size for C.quadrangularis L.was estimated to be about 2C=1.410 pg.Compared with other members in the Cissus genus,the genome size for C.quadrangularis L.could be said to have doubled.This can be attributed to polyploidy activities along the evolutionary lineage2.The root tips of C.quadrangularis L.were used to evaluate its chromosome numbers by fluorescence microscopy combined with DAPI stain.The chromosomes were small in size and it was not easy to identify centromeres except in two pairs.Fluorescent images indicated the chromosome numbers for C.quadrangularis L.as 2n=48.Considering the basic chromosome numbers in Cissus genus(n=11 or n=12)based on the chromosome numbers identified for other members in the genus,it can be speculated that C.quadrangularis L.has a tetraploid genome.The occurrence of two pairs of big chromosomes with identifiable centromere could further lead to speculations of tetraploidy genome in C.quadrangularis L.3.DNA was extracted from fresh leaves using modified CTAB protocol yielding DNA with acceptable concentration and purity for Next Generation Sequencing.Using a combination of low-pass genome sequencing and bioinformatic analysis,the genome components for C quadrangularis L.were identified.It was inferred that C quadrangularis L.genome is made up of about 52%repetitive elements and 48%singletons.Annotation of the repetitive elements indicated the long terminal repeats(LTR-retrotransposons)were the dominant cluster components ranging to about 40%.Analysis on the LTR revealed two LTR superfamilies;Copia and Gypsy in the annotated clusters.A comparison of repetitive elements between C.quadrangularis L.with a close relative(Vitis vinifera)revealed higher diversities in the considered clusters.The high diversities could be attributed to evolutionary activities leading to the changes or could be due to polyploidization or whole genome duplication.