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MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF PAPAYA GENOTYPES

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2016
Jai Prakash
DIVISION OF FRUITS AND HORTICULTURAL TECHNOLOGY, INDIAN AGRICULTURAL RESEARCH INSTITUTE, NEW DELHI
MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF PAPAYA GENOTYPES
MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF PAPAYA GENOTYPES
M.Sc

The papaya (Carica papaya L.) is an important fruits for the growers of the tropical and subtropical agro-climatic regions across the globe. In India papaya ranks 5th with regards to area and production (NHB, 2015) among the fruit crops. Papaya varieties are typically either dioecious or gynodioecious. Being a polygamous plant, it has basically three types of sex viz. male, female and (transgender) hermaphrodite. The experiment was carried out to characterize papaya genotypes on the basis of morphological and reproductive traits, estimate genetic diversity among papaya genotypes using molecular markers and determine the population structure of papaya genotypes and identification of superior parent(s) for hybrid development. Both gynodioecious and dioecious, dwarf to tall fruiting papayas are being commercially has been observed growing in different states of the India, primarily in tropical and subtropical regions. Among them several are being originated due to natural crossing and developed as population and are serving as source of genetic and morphological diversity for domesticated papaya; therefore, morphological and molecular characterization of 23 genotypes including some commercial varieties and hybrids was carried out. A significant amount of morphological diversity was observed among the studied genotypes of papaya, especially within reproductive traits. The highest distinctness was observed between p-7-15 and P-7-2 & P-7-2-V among the gynodiecious genotypes of papaya based on Euclidean distance in a range of 2.16 to 7.39. The two wild species Vasconcellea cundinamarcensis and Vasconcellea cauliflora were observed in same cluster no ‘I’ along with P-9-25 among the dioeciuos genotypes. The closed genotypes were RCTP-I and P-9- 15-5 followed by Pusa Nanha and P-14-6 based on morphological quantitative traits. Twenty Simple Sequence molecular markers were also used to assess the genetic diversity of 23 genotypes to determine levels of heterozygosity, genetic differentiation, and population structure. The gene diversity range 0.29 to 0.73 with an average of 0.59. The maximum gene diversity (0.73) was observed in primer P3K2981YCO followed by (0.66) in primer CPM1606CC and (0.65) in primer P3K2696CC. Marker P3K2981YCO had produced the highest PIC value of 0.68 followed by CPM1606CC with 0.58 while marker CPM1774CC had the lowest PIC of 0.25. The maximum observed heterozygosity (0.43) was in two marker ctg27cc and P3K2696CC. The higher level of heterozygosity (48%) was recorded within the individuals among population. Unweighted Pair Group Method of Arithmetic averages (UPGMA) dendroagram genotypes were divided into two broad clusters represented by six and seventeen genotypes respectively. The radiant coefficient ranged from 0.05 to 1.00. Cluster ‘I’ had 6 papaya genotypes. However, P-7-15 genotype was most diverse among the population. Comparisons between inbred lines and varieties indicate a greater amount of genetic diversity existing within the populations

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