Phytochemical Diversity in Relation to Cytogenetic Variability in Inula racemosa Hook.f., an Endangered Medicinal Plant of Himalayas

Inula racemosa, a resourceful critically endangered medicinal herb in the Himalayas is traditionally utilized to cure various human disorders. The species is a wealthy source of sesquiterpene lactones has many pharmacological properties. To quantify and identify the best genetic stocks for a maximum build-up of desired metabolites (isoalantolactone and alantolactone) among existent cytotypes in the species, LC-MS/MS analysis was made. The other comprehensive experiments carried out at present included detailed meiotic examinations of different populations collected from different areas of Kashmir Himalayas. The results presented the occurrence of variable chromosome numbers as n=10 and n=20 in different populations, but the tetraploid cytotype (n=20) is new for the species. The LC-MS/MS investigation revealed significant variability in the content of sesquiterpene lactones in different plant tissues (stem, leaf, and root). An upsurge in the quantity of isoalantolactone and alantolactone was noticed with increasing ploidy levels along the increasing altitudes. Therefore, a habit to accumulate abundant quantities of secondary metabolites and increased adaptability by species/cytotypes thriving at higher altitudes is seen among tetraploid cytotypes during the present investigation. Also, the chromosomal variations seem to enhance the flexibility of polyploid species primarily at upper elevations. Thus, the present study strongly provides quantification of elite cytotypes/chemotypes with optimum concentration of secondary metabolites.

Does divergence from normal patterns of integration increase as chromosomal fusions increase in number? A test on a house mouse hybrid zone

Chromosomal evolution is widely considered an important driver of speciation because it can promote the establishment of reproductive barriers. Karyotypic reorganization is also expected to affect the mean phenotype, as well as its development and patterns of phenotypic integration, through processes such as variation in genetic linkage between quantitative trait loci or between regulatory regions and their targets. Here we explore the relationship between chromosomal evolution and phenotypic integration by analyzing a well-known house mouse parapatric contact zone between a highly derived Robertsonian (Rb) race (2n = 22) and populations with standard karyotype (2n = 40). Populations with hybrid karyotypes are scattered throughout the hybrid zone connecting the two parental races. Using mandible shape data and geometric morphometrics, we test the hypothesis that patterns of integration progressively diverge from the “normal” integration pattern observed in the standard race as they accumulate Rb fusions. We find that the main pattern of integration observed between the posterior and anterior part of the mandible can be largely attributed to allometry. We find no support for a gradual increase in divergence from normal patterns of integration as fusions accumulate. Surprisingly, however, we find that the derived Rb race (2n = 22) has a distinct allometric trajectory compared with the standard race. Our results suggest that either individual fusions disproportionately affect patterns of integration or that there are mechanisms which “purge” extreme variants in hybrids (e.g. reduced fitness of hybrid shape).