Studies on cytomorphological and bio-chemical differentiation of ten species of Ipomoea and their mutagenic effectiveness

Abstract

Ten Ipomoea species viz., I. aquatica Forks., I. carnea Jacq., I. hederacea Jacq., /. maxima (L.F.) Don. Ex Sweet, /. paniculata (L.) R. Br., I. pes-tigridis Linn., /. pulchella Sensu., /. quamoclit Linn., I. turbinata Lagasca and /. turpethum Br. Prodr. belonging to the family Convolvulaceae were studied from cytomorphological, biochemical and mutagenic points of view. A few of the findings in respect of the morphological characters can be considered as an additional information in the present study compared to available reports. Particularly the qualitative characters regarding root/tuber, stem and leaf, flower, capsule and seed were found to vary from the reports made in Flora of Bangladesh and Flora of British-India. The diploid chromosome number was found to be 30 in all the ten species of Ipomoea. The chromosomes were identified by quantitative method based on the data -recorded from three metaphase plates. Differences were observed regarding chromosome length, types and total chromatin length (TCL) among the ten species. The longest chromosome as well as maximum chromatin length were observed in /. carnea. The shortest chromosome along with minimum chromatin length were found in/. maxima. Asymmetric karyotype was found in case of /. maxima and I. hederacea. The proposed standard karyotype indicated /. camea to be more primitive, and/. maxima and/. hederacea of advanced nature. Percentage of rod bivalents were extensively more than the ring bivalents. No univalent and multivalent were observed in any species of the present investigation. Mean chiasma frequency per PMC were found to range from 16.22 (/. pulchella) to 17 .07 (/. maxima). Chi as ma frequency per bivalent were more or less same in all the species and it ranged from 1.08 (/. panicullata and I. pulchella) to 1.14 (/. maxima). For protein and sugar estimation both premature and mature leaves of all the Ipomoea species were used. The highest and lowest percentage of protein values were determined in I. turpethum (8.96%) and I. turbinata (5.29% ), respectively. The highest sugar content (3.11 %) was found in /. paniculata and the lowest (1.23%) in I. hederacea. It was observed that the edible species /. aquatica showed a good amount of protein (8.46%) and sugar (2.92%) compared to that of /. turpethum and I. paniculata. It was also found that the protein and sugar content was always higher in mature leaves than the premature leaves. The cytological observations from treated root tip cells of onion revealed that the extracts of different lpomoea species had a strong mutagenic effect. The different types of chromosomal anomalies were found among which bridge chromosomes, laggards, fragments, ring, micronuclei, etc. were noticeable. With the increase of extract's concentration and treatment duration chromosomal anomalies were also found to increase. In the present investigation it was also observed that the overall doses of I. aquatica showed a little radiomimetic effect in Allium cepa roots compared to that of other species.