Genetic divergence and association of genotypes and phytochemicals in Asparagus adscendens Roxb in Himachal Pradesh

Abstract

newline ABSTRACT newlineThe genomic DNA polymorphism and phytochemical variation of Asparagus adscendens Roxb. was studied using RAPD-PCR and HPLC analysis. For initial RAPD analysis, seventy five oligo-nucleotide decamer primers were used to amplify the genomic DNA from ninety six accessions of Asparagus adscendens collected from different locations of eight districts of Himachal Pradesh (twelve from each district). Out of these fifteen primers generated RAPD fingerprints that revealed, 127 bands, in which 112 bands were found to be polymorphic. Total number of amplified fragments with fifteen primers were 7985 and size range of amplified fragments was 190 to 3280 bp. The ninety six accessions were clustered into three major groups in the phylogenetic tree; which was further confirmed by principle coordinate analysis (PCoA). Maximum percentage of polymorphism (78.74%) was present in a population collected from Solan district, whereas the minimum percentage of polymorphism (64.57%) was present in population collected from Kangra district. AMOVA indicated high level of genetic diversity, i.e. 88% of the genetic variation was attributed to differences within populations, while 12% of the genetic variation was attributed to differences among populations. In a preliminary phytochemical analysis of the roots of Asparagus adscendens showed the presence of sterols, tri-terpenoids, phenols, ketones and saponins. Root accessions of genotype AAH-A3 were collected in two different seasons to evaluate the content of sarsasapogenin present in it; one time in the month of January and again in the month of May from the site Kumarhati of district Solan (Himachal Pradesh). Samples collected in the month of January contained 2.1% of sarsasapogenin; whereas sample collected in the month of May contained only 1.0% of sarsasapogenin. The seasonal study revealed that the autumn or winter season was best harvest time to obtain sarsasapogenin, a steroidal glycoside as well as other metabolites which were also in higher amounts. Based on the results of the present HPLC analysis, it can be concluded that with the change of geographical conditions the content of sarsasapogenin also changed among the twenty four accessions of Asparagus adscendens collected from eight districts of Himachal Pradesh (three of each district). All three accessions of district Mandi and one accession of district Solan contained highest content of sarsasapogenin i.e. above 2.1%; and these were genetically related with the accessions of the district, Una and Hamirpur; which contained lowest content of sarsasapogenin i.e. below 0.8%. May be the geographical region of district Mandi was more suitable for the phytochemical accumulation. The genetic variations of plants did not seem responsible for the amount of the phytochemical variations in the roots of newlineviii newlineAsparagus adscendens. The results obtained under this study clearly shown that the geographical diversity may not necessarily follow the same pattern of genetic diversity. Geographical diversity is important, but not the sole factor of determining the phytochemical variability in Asparagus adscendens Roxb.