Karyological Studies and Chromosomal Analysis of Fifteen Accessions of Trichosanthes cucumerina L. (Snake Gourd)

This is to investigate variability of karyological and chromosomal numbers of fifteen accessions of Trichosanthes cucumerina var anguina and Trichosanthes cucumerina var cucumerina L. (Snake Gourd) from four geopolitical zones in Nigeria. The studies were carried out using the root tips from the plant seedlings. The fifteen ecotypes were germinated in glass petri dishes covered with moisten cotton wool in the laboratory of the Department of Plant Science and Biotechnology, College of Natural Sciences, Michael Okpara University of Agriculture, Umudike, Umuahia, Abia State, Nigeria and was observed for 6-11days. The glass petri dishes were kept in a dark cupboard for warmth needed for germination. Squashed and stained root tips with acetone orcein. The viewed somatic chromosome number of the fifteen ecotype of snake gourd (Trichosanthes cucumerina L.) studied from four geopolitical zone of Nigeria was 22. The karyological formular differ from each other. The karyological formular ranged from(5m+6sm-9m+2sm). Short arm(S) length ranged from (1.28±0.01-1.38±0.05). Long arm (L) length ranged from (1.79±0.02-1.90±0.03). The total length (S+L) ranged from (3.08±0.01-3.33±0.13). The arm ratio(L/S) ranged from (1.29-1.48). The relative value (S/L) demonstrated variability among the ecotypes which varied from (0.67 – 0.72um). Centrometric index (S/L+ S/µm) affirmed variability among the ecotypes which varied from (1.95 – 2.15). Coefficient of variation of the fifteen ecotypes varied from (18.29 – 28.63%). The total form in percentages ranges from (66 – 77%). Standard deviation among the ecotypes studied ranges from (0.29 – 0.46). The variance among the 15 ecotypes affirmed variability (0.08 – 0.22). The mean displayed differences among the ecotypes ranged from (1.54 – 1.67). The long arm and short arm lengths determined were more at zero (0.00) which demonstrated closest genotype with same karyotype composition in the four ecotypes were closely related. There were ecotypes closer to zero such as 0.02, 0.08, 0.04, - 0.04, have almost the same karyotype composition. Ecotypes within red colour lines have close karyotypes similarities (V2/V3). V3, V14, V11, V6 and V8 were within yellow colour lines and shared karyotype similarities. V7, V14, V12, V15, were in the same blue lines and shared karyotype similarities. V10, V2, V5 and V4 were distinct from others in terms of their karyotype compositions. The chromosomal number of the fifteen accessions are the same 22. The karyotypes have similarities such as V2, V3, V14, V11, V6 and V8. Snake gourd from Edo State, Kadroko, Nassarawa State, Ukwa, Abia State and Ilorin, Kwara State shared karyotype similarities. V10, V2, V5 and V4 displayed variabilities among ecotypes studied.