Study of intergeneric, mutagenic progenies and validation of intergeneric hybridity using markers in papaya

Abstract

Papaya is one of the most important fruit crops valued for its rich nutrient content mainly vitamin A and C. Papaya Ringspot Virus (PRSV) is the major impediment in the commercial cultivation. The present investigation on “Study of intergeneric, mutagenic progenies and validation of intergeneric hybridity using markers in papaya (Carica papaya L.)” was carried out at the Division of Fruit crops, Indian Institute of Horticulture Research, Hesaraghatta, Bengaluru during 2011-2012.The experiment on mutation was carried out using Ethyl Methane Sulphonate (EMS), along with KNO3 to increase the efficacy of the mutagen. EMS was used to induce variability in the variety Arka Prabhath with the objective of inducing variability for plant height. The LD50 was observed to be at 0.3 per cent EMS concentration. The observations were recorded at first harvest in M0 generation progenies and the selected progenies were raised for M1 generation. In M0 generation, many morphological abnormalities were observed, which showed the possibility of largevariability in M1 generation. Population derived by selfing a hermaphrodite tolerant plant for ‘PRSV-p’ from the intergeneric cross of Carica papaya var. ‘Arka Surya’ x Vasconcellea cauliflora was evaluated for morphological characteristics. Molecular characterization to confirm the hybridity was done with ISSR and SSR markers. The primers UBC-841, UBC-836, UBC- 815 and SSR primer P8K72CCF/R showed clear bands, which confirm the hybridity of intergeneric progenies. In the present investigation regular pairing of homologous chromosomes was observed in Carica papaya, Vasconcellea cauliflora and their intergeneric hybrids. There was no heteromorphic chromosomal distribution in hybrids. The intergeneric hybrids, which were found to be tolerant to ‘PRSV-p’ were assorted for in vitro propagation as conventional seed propagation may result in loss of fixed attributes, effective establishment of explant was noticed when they were treated with fungicide (Bavistin 0.2%) and bactericide (Streptocyclin 0.1%) along with surface sterilant mercuric chloride (0.1%) for 4 min. The explants cultured on MS medium supplemented with BAP (0.5 mg/L), and NAA (0.1 mg/L) and GA3 (1 mg/L) recorded good elongation of shootlets.