Phylogenetic diversity and relationships of some medicinally important species of Solanum as revealed by seed morphometric and biochemical analysis

Morphometric parameters like seed length and width; dry seed weight; biochemical data like total soluble seed protein content per gm of tissue as well as protein content per grain of seed were analyzed in the eight selected species of Solanum (S. nigrum, S. americanum, S. villosum, S. torvum, S. xanthocarpum, S. sisymbriifolium, S. macranthum and S. indicum). It was revealed that S. macranthum and S. americanum produce heaviest and lightest seeds respectively. S. nigrum and S. macranthum contain maximum and minimum soluble seed protein per gm of tissue, while protein contents per seed were highest and lowest in S. macranthum and S. americanum respectively. Phylogenetic relationship among the selected species has been established by constructing dendrograms based on morphological and biochemical data separately which show striking similarity. From the dendrograms it was revealed that the selected species are clearly divided in to two major clusters- upper cluster (UC) and lower cluster (LC). UC is sub-divided into two sub-clusters, viz. UC1 and UC2. S. nigrum complex and S. torvum are placed in UC1 and UC2 respectively. LC is also divided in to two sub-clusters- LC1 and LC2. S. sisymbriifolium, S. macranthum and S. indicum are closely associated and placed in LC1, while LC2 is represented by S. xanthocarpum. The relationship and diversity among these species were confirmed through polygraph analysis. Based on overall seed morphometric and biochemical characters, the genus Solanum can be divided into two sub genera and the distribution of species in these two sub genera is in contrary to conventional classification.