MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF PAPAYA GENOTYPES
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Date
2016
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DIVISION OF FRUITS AND HORTICULTURAL TECHNOLOGY, INDIAN AGRICULTURAL RESEARCH INSTITUTE, NEW DELHI
Abstract
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 āIā 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 āIā 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
Description
t-9487
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