DNA analysis as a tool for Genetic Studies and Molecular Breeding in Cassava (Manihot esculenta Crantz)

Abstract

Tapioca (Manihot esculenta Crantz) is an important tuber crop of Kerala. Research on various aspects of tapioca including crop improvement is going on at Central Tuber Crops Research Institute, Trivandrum. Assemblage of available cassava varieties and analysis of genetic variability and diversity available is important for better breeding practices and crop improvement. The present work is aimed at molecular characterization of popular varieties of cassava from Kerala. This would help in safeguarding the farmers right under the IPR regime. The objectives of the study includes (1) Study of molecular variability and molecular diversity available in local varieties of cassava and identification of distant varieties for planning hybridization program, (2) DNA fingerprinting of released varieties and popular local varieties selected by farmers to protect the plant breeders and farmer s right and (3) DNA analysis of cassava mosaic free accessions, whitefly resistant accessions and apparently hybrid populations to confirm their resistance. Around 300 varieties of cassava including local cultivars from different parts of Kerala, popular and released varieties and interspecific hybrids from the cassava germplasm collection at CTCRI Thiruvananthapuram were selected for the genetic variability/diversity and CMD resistance studies through DNA finger printing. The morphological features of the studied varieties were documented. PCR amplified microsatellite (SSR) markers were exclusively used for the DNA analysis and diversity study. Specific primers were used for the CMD resistance analysis. Statistical analysis of the data, construction of dendrogram based on cluster algorithm and population genetic studies were done with popular softwares. The study revealed the diversity among varieties collected from Idukki, a typical cultivating area varied from 44 to 90%. Between the old and new collectionsof cassava, the similarity ranged from 80 to 100% and 68 to 98% respectively.