Saraca asoca, (Roxb.) De Wilde (Roxb.) De Wilde

Hegde, Satisha, Pai, Sandeep Ramchandra, Bhagwat, Rasika M., Saini, Archana, Rathore, Poonam Kanwar, Jalalpure, Sunil Satyappa, Hegde, Harsha Vasudev, Sugunan, Attayoor Purushottaman, Gupta, Vidya S., Kholkute, Sanjiva D. & Roy, Subarna, 2018, Genetic and phytochemical investigations for understanding population variability of the medicinally important tree Saraca asoca to help develop conservation strategies, Phytochemistry 156, pp. 43-54 : 48-50

2.5. Relationship between phytochemical and molecular analysis of S. asoca

How biodiversity changes over evolutionary time, is an interesting fundamental aspect which depicts modes of species diversification ( Lewitus and Morlon, 2016). However, natural selection maintains existing function and drives adaptation, which leads to altering patterns of diversity at the genetic level ( Good et al., 2014). In the present study, genotypes showed two major clusters including several sub-groups, while diverse variations were observed in specialized metabolites tested in the S. asoca populations. However, excluding minor deviations, UPGMA and Bayesian Models (STRUCTURE) showed close association of genotypes according to their different geographical areas of collection. Overall, the cluster grouping of chromatograms of phytochemical constituents analysed from leaf and corresponding bark samples of 106 accessions of S. asoca collected from 11 populations were not complete match. Similarly, cluster grouping of chemotypes of both leaf and bark failed to match with those obtained with their genotypes. Although, multiple logistic regression analysis predicted some association between few loci with GA, EPI and CAT (Suppl. Table 5 ), PCA for phytochemical data failed to distinguish the populations (Suppl. Fig. 6a) and no distinct complete linkages could be drawn using it. Therefore, no direct congruence in relationship of phytochemical and molecular markers could be established. Nonetheless, it should be considered that, for phytochemical analysis, only three standards were studied and 74 loci were worked for genetic analysis.

Natural selection and its expression depend on various factors including environmental condition. It is well known that genetic factors, coupled with various epigenetic factors and seasonal variations, play a role in production of specialized metabolites. While it is appreciated that the use of ISSR markers alone may not be able to capture all the genetic characteristics, the tool is considered adequate to provide information on the basic differences in genotypes particularly from the evolutionary genetic viewpoint as is done in this study. Both biotic and abiotic stresses play critical role in specialized metabolites production where in S. asoca the environmental changes also might be a major reason for observed variations in genetic and phytochemical profiles. However, the present investigation is expected to provide the baseline data for conservation practices and for selection of varieties for propagation and it should facilitate our broader understanding of the genetic and phytochemical diversities in S. asoca . The results will therefore be beneficial to develop conservation strategies and for quality control studies in S. asoca .