Electronic Theses and Dissertations

Identifier

1214

Ramhari Thapa

Date

2014

Document Type

Thesis

Degree Name

Master of Science

Major

Biology

Committee Chair

Randall J. Bayer

Committee Member

Duane D. McKenna

Committee Member

Jennifer R. Mandel

Abstract

Tomato (Solanum lycopersicum L.), broadly divided into two varieties: Solanum lycopersicum var. lycopersicum (domesticated tomato) and the weedy Solanum lycopersicum var. cerasiforme (cherry tomato), is closely related to the wild tomato species Solanum pimpinellifolium. Studies show presence of a very low genetic diversity among tomato cultivars, which is estimated to be lower than 5% of that available in nature. With the estimation of such a low level of genetic variability in the germplasm, assessment of the extent and nature of the genetic variation in tomatoes would be important for breeding and genetic resource conservation programs. I used AFLP data to analyze the genetic variability within the germplasm of Solanum lycopersicum var. cerasiforme (112 accessions), and genetic variability along with fruit morphological diversity in the accessions of Solanum lycopersicum var. lycopersicum (219 accessions) from different parts of the World. Cherry tomato (Solanum lycopersicum var. cerasiforme) in terms of genetic distance and molecular variance (1% molecular variance) was very close to Solanum lycopersicum var. lycopersicum than its wild sister taxa Solanum pimpinellifolium (20% molecular variance). It also showed more genetic diversity (Hj, 0.42052-0.48361) than that of S. l. lycopersicum (Hj, 0.26008-0.42017); and among its geographic groups, South American accessions had more genetic diversity (Hj, 0.43703-0.48361) than that of Mesoamerican (Hj, 0.42052-0.46946) and Caribbean accessions (Hj, 0.42287). The germplasm of S. l. lycopersicum showed presence of more genetic diversity in the accessions from Western South America, Caribbean and Mediterranean regions (Hj, 0.42017), and Mesoamerica (Hj, 0.41790), the places associated with tomato domestication and subsequent dispersal after domestication.Studied tomato germplasm was divided into three genetically distinct clusters (K=3), and one of the clusters (cluster 3) in S. l. lycopersicum

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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