Molecular Phylogeny of Zingiberoideae
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The investigation corroborates generation of molecular tools for understanding the molecular phylogenetics of the sub family Zingiberoideae. Results presented include proper systemic characterization according to the ethno-medicinal significance, chromosome number and associated karyo morphometric analysis, genetic assessment at the inter-varietal level, inter species and inter generic level for the genotypes, development of flow cytometric protocol for estimating nuclear DNA amounts in absolute units and understanding the dynamics of chromosome number, nuclear DNA content and development of genome size based phylogeny. An important aspect for a proper phylogenetic assessment is understating the ethno medicinal significance. The field study during the collection of germplasm was also supported by the questionnaires of the herbal healers of the locality based on their use in traditional medicine followed by documentation. The survey revealed that the rhizome is the main part which is being used for herbal medicinal preparation and for treating gastrointestinal problems. The protocol of rapid squash technique was optimised for determination of somatic chromosome count. The chromosome numbers were investigated for 9 species ranging from diploid to nonploid. The chromosome count for two species was reported for the first time. The comparatively high disparity index (DI) value found in H. chryoleucum, C. zedoaria and K. galanga corresponds to the heterogeneous assemblage of chromosomes in these species. While lower values of DI found in other members point (C. caesia, C. longa, H. coronarium, H. gardnerianum, K. angustifolia and K. pulchra) towards the general homogeneity found in various species of sub family Zingiberoideae. Genetic assessment of the local cultivars of North East (NE) India signifies high variation implicating that turmeric genetic resources need conservation. Inter species genetic relationship showed wide variation in the genetic diversity in the wild genotypes of Hedychium and Kaempferia. The inter generic study revealed the unique genetic clustering where the species were clustered according to their genera. The flow cytometric estimation of nuclear DNA content for the sub family Zingiberoideae was optimised in a modified nuclear isolation buffer. Statistically significant variation in nuclear DNA amounts were observed among different tissue type of six different Zingiberaceous plant studied. Intra-species variation in nuclear DNA content was estimated for cultivated turmeric (C. longa) variety. Population of Assam showed the highest intra-species variation of nuclear DNA content. Two fold intra-species variation was observed among the 19 cultivated turmeric varieties. Nuclear DNA content was also estimated for 26 Zingiberaceous species of which 10 were reported for the first time. Nuclear DNA content of 10 Zingiberaceous species was reported for the first time. Fold variation of 4.74 fold was reported within a narrow but bio-geographical hotspot of India. A phylogenetic tree was constructed based on the inter species variation in the nuclear DNA content. In a sample of Zingiberaceous species, nuclear DNA content (1C) was a function of the number of chromosome compliments (2n), as represented by the linear equation y= 18.86 x + 1052, r2= 0.087, the near zero regression coefficient signifies the chromosome number changes are due to fission and fusion...
Supervisor: Latha Rangan and Vikash Kumar Dubey
BIOSCIENCES AND BIOENGINEERING