Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2007
Publication Date: 2/1/2008
Citation: Behera, T., Singh, A.K., Staub, J.E. 2008. Genetic Diversity Analysis of Indian Bitter Gourd (Momordica Charantia L.) Allows for the Development of Crop Improvement Strategies. Scientia Horticultureae. 115:209-217. Interpretive Summary: Bitter gourd is an economically important member of the taxonomic family called the Cucurbitaceae that is widely cultivated as a vegetable (i.e., green and white fruit) in India, China, Malaysia, Africa, and South America. Although the general chemical composition of bitter gourd fruit is similar to other cucurbits, it possesses comparatively high concentrations of ascorbic acid (vitamin C) and iron. White-fruited Indian varieties are, in fact, relatively high in health-promoting compounds such as polypeptide-p, phenolics, polyphenolic compounds, and natural oxidants and antioxidants. Bitter gourd is used as a traditional medicine for diabetes (e.g., India, China, and Central America). The diverse visual characters (i.e., sex expression, growth habit, maturity, and fruit shape, size, color and surface texture) of bitter gourd in India provide for relatively broad diverse plant species. However, the genetic diversity (GD; genetic variation) of bitter gourd at the DNA level is not known. Obtaining estimates of genetic diversity is extremely importance to plant improvement since it increases the efficiency and effectiveness of selection of improved cultivars. Thus, a study was undertaken to define the GD of bitter gourd accessions in the country of origin, India, using DNA analysis. DNA analysis of 38 accession of diverse geographic origin indicated that GD among some accessions was great and allowed for the identification of potential parents for hybrid production to increase yield and quality. Public and private plant breeders can use this information to increase to develop new, more genetically diverse bitter gourd varieties more effectively. Since bitter gourd is high in nutritive value/medical attributes and can be grown in the U.S. as a "new crop" this information provides for opportunities for growers to expand their crop array and increase their global competitiveness.
Technical Abstract: Bitter gourd (Momordica charantia L. var. minima and var. maxima) or bitter melon is one of the most economically important cucurbit species worldwide. Although India is the center of origin of bitter melon, and cultivars and landraces of this species are widely cultivated in Asia, a rigorous assessment and comparative analysis of genetic diversity among exotic (landraces) and elite germplasm has not been made. Therefore, a genetic analysis of 38 diverse Indian bitter melon accessions was performed using 29 random amplified polymorphic DNA (RAPD) and 15 inter-simple sequence repeat (ISSR) markers. RAPD primers yielded 208 amplicons of which 76 (36.5%) were distinct and repeatable providing an average of 2.6 polymorphisms per primer. RAPD amplicons per primer ranged from 3 (OPE-19, OPW-09) to 15 (OPW-05), and varied in size from 200 bp to 3,000 bp. Fifteen ISSR primers provided a total of 125 bands of which 96 (74.7%) were polymorphic. Polymorphic ISSR markers ranged from 0 (UBC-841) to 12 (UBC-890) providing a mean of 6.3 amplicons per primer that ranged in size from 150-2,700 bp. ISSR markers detected a higher level of polymorphisms (74.7%) when compared to RAPD markers (36.5%). Nevertheless, the concordance among bitter gourd accession groupings after cluster analysis was relatively high (r = 0.77), indicating that RAPD- and ISSR-based diversity assessments in this germplasm array were generally consistent. However, accession groupings within cluster sub-groups derived from RAPD and ISSR marker analysis were dissimilar. Cluster sub-group placement after combined RAPD + ISSR analyses was, nevertheless, identical to ISSR cluster groupings. The M. charantia var. charantia (domesticated) and var. muricata (wild, free-living) accessions examined were genetically distinct, and these differences provided for the development of strategies for genetic analyses and crop improvement in this species.