Intraspecific genetic variability, differentiation and evolutionary relationships revealed through microsatellite loci in seven economically important species of Calamus L.

Kurian, B., A. S. Hemanthakumar, Jacob J, Wickneswari R, Choong C Y, Sarmah P, Shefeek S, Vishnu V N, Sajithkumar S V, and K K Sabu. 2019. Intraspecific genetic variability, differentiation and evolutionary relationships revealed through microsatellite loci in seven economically important species of Calamus L. Journal of Forestry Research DOI: 10.1007/s11676-019-00984-z

Abstract
Population density, species richness and critical population parameters are crucial in determining the levels of gene diversity in dioecious species of the genus Calamus. The extent of intraspecific and intrageneric genetic variability in Calamus from the southern Western Ghats of India was studied using 26 microsatellite markers by sampling 227 individuals belonging to seven economically important species. The heterozygosity of microsatellite loci ranged from zero to 0.78. Average gene diversity within species was 0.13; in all species it was 0.18 and amongst species was 0.06. The Shannon Information Index was the lowest for Calamus metzianus (0.11), whereas it ranged from 0.16 to 0.26 for other species. The expected heterozygosity varied from 0.08 to 0.18. Calamus hookerianus and Calamu travancoricus showed the highest genetic differentiation (44%) revealed through Fst values, whereas the lowest (22%) was observed between Calamus gamblei and Calamu thwaitesii. Population structuring and phylogenetic analysis differentiated the seven species. Due to overexploitation and loss of rare alleles, small populations could lead to fertilization between closely related individuals, resulting in inbreeding and increasing the risk of extinction. This could be important for species such as C. metzianus where allelic polymorphism was 23%, whereas for all other species it was 38% to 46%. Genetic diversity “micro-hotspots” were identified from the protected area network of the southern and central Western Ghats with highest observed heterozygosity. Four micro-hotspots from the Agasthyamalai Biosphere Reserve and the Pushpagiri Wildlife Sanctuary may be possible for long-term conservation programs. The findings of this study lay a strong foundation for strengthening protected area networks, especially areas with intermediate levels of disturbance.

Keywords
Genetic diversity Differentiation Population structure Conservation Microsatellites Calamus spp. 

ISSR and SSR markers reveal sex-specific DNA sequences in three Calamus species from India

Calamus species yields the raw materials for the cane industry. However, the extraction of the cane from the forests is being carried out indiscriminately without considering the sustenance of the species. Plants of both sexes should co-exist for reproductive success. The sex of Calamus plants can be identified only after flowering and hence proper planning of managed forestry practices cannot be accomplished. A study was carried out in this background and male specific ISSR markers for C. tenuis and C. flagellumand SSR markers for C. thwaitesii were identified. The diagnostic potential of these markers can be exploited to sex the Calamus species at the seedling stage for proper breeding and agroforestry management.

This article has just been published:

Title ISSR and SSR markers reveal sex-specific DNA sequences in three Calamus species from India Journal Agroforestry Systems, (), 1-5 DOI 10.1007/s10457-016-9952-9

This article is available as 'Online First':  http://link.springer.com/article/10.1007/s10457-016-9952-9

Genetic studies in rattan palms (Calamus sp.) using SSR markers

Natural variation is essential for conservation and utilization of plant genetic resources. Human interference on forests may cause depletion of natural genetic variation in the gene pool and even to genetic erosion of certain species. Rattans are one such species currently under crisis due to over-exploitation. They represent high value non-wood forest produce primarily used for making furniture, handicraft items and an important raw material in the cottage industry which contributes significantly in rural economy. There are about 1 lakh people in Kerala living out of this valuable resource. However, number of small scale industrial (SSI) units depending on these forest produce are decreasing drastically.  Besides, over exploitation of the rattans has exerted severe pressure on existing populations and sometimes resulted in loss of genetic diversity.

There are about 600 rattan species in 13 genera globally and 51 species in 4 genera in India, of which 75% are endemic and 40.5% threatened. The Western Ghats region of India is rich in species diversity of rattans with one genus, viz. Calamus having 27 species of which 21 are identified.

Presently associated (as Principal Investigator) to a research project on ‘Genetic studies on selected rattan palms (Calamus sp.) using microsatellite markers’.

Objectives of the project are to collect natural populations of the selected rattan palms, viz. C. brandisii, C. gamblei, C. nagabettai, C. thwaitesii, C. travancoricus and C. hookerianus and analyze genetic diversity, population structure and differentiation using SSR markers.

The project is being funded by Kerala Biotechnology Commission/KSCSTE.