VARIABILITY ASSESSMENT AMONG MONOTYPIC GENUS TAMARINDUS DISTRIBUTED IN ASSAM (INDIA) USING ISSR MARKERS

Abstract

Tamarindus popularly known as Tamarind is a tropical or semi-tropical evergreen tree which can withstand drought for extensive period of time and hence, sustained as monotypic genus having various environmental and social issues, as human and animal food, a medicine and used for fuel as well. Several ISSR markers were used to study the genetic diversity and population structure of this important and monotypic medicinal plant collected from six different Agro-climatic zones of Assam within Northeast India as there is no information on the available genotypes of the species in the study area. Fresh and healthy leaf samples were collected from sites geographically located between 22°19' to 28°16' N latitude and 89°42' to 96°30' E longitude with elevation varying between 45 m to 1,960 m spread over an area of 78,438 km². Morphological characterizations of vegetal variants were done along with extraction of DNA with CTAB method followed by PCR technique. Dendrograms developed using the UPGMA and AMOVA was done with the help of GenAlEx for determination of genetic differentiation between six populations. Wide morphological variation for qualitative morphological traits among identified 94 T. indica genotypes across six different Agro-climatic zones of Assam is justified by Cophenetic Correlation Coefficient (CP) which is 0.8280; and Molecular variance (95% among populations and 5% within populations).

The analysis of individuals (variables) using polymorphic ISSR revealed high value of genetic diversity within Assam and clearly separate populations of southern Assam under Hills zone and Barak valley zone from Upper Brahmaputra valley and North Bank plain zone; and Lower Brahmaputra valley and Central Brahmaputra valley zones of Assam. This is the pioneer study of this kind in T. indica from this region of Northeastern India proximate to the eastern Himalaya mega biodiversity hotspot.