A comparative evaluation of micro-propagated and seed derived plants of intergeneric papaya hybrids

Abstract

As papaya is susceptible to papaya ring spot virus (PRSV) disease, it is a challenging task to obtain the true-to-type plants with virus resistance. Hence, a comparative study using morphological traits, fruit traits and above all, resistance to PRSV of field established micro-propagated and seedling derived plants of intergeneric hybrid (IGH) (Carica papaya cv. Arka Surya × Vasconcellea cauliflora L.) was conducted to obtain virus resistant plants coupled with desired fruit traits. Plantlets were raised using shoot tips of seeding plants from selected advanced intergeneric papaya hybrids (IGH 4-13 and IGH 12-2) on MS media supplemented with 3% sucrose + BAP 1µM + GA3 1µM + IAA 0.1 µM; phytagel / gelrich 0.25%. Intergeneric hybrid plants (micro-propagated and seedling) were field planted and evaluated for sex determination, morphological traits, fruit traits and PRSV resistance. Micro-propagated IGH plants showed significant morphogenic difference, when compared to plants raised through seed like dwarf stature, bearing fruits lower on the stem, flowering at an early time and lower stem circumference, internode length and number of leaves. Among the tissue culture plants, derived from the same mother culture uniformity with respect to morphological, fruit, yield and PRSV tolerance were obtained indicating the identical production of quality plants as the mother culture. Based on the final scoring for PRSV tolerance, the micro-propagated plants viz., IGH.SD.3 and IGH.SD.4 showed field tolerance to PRSV coupled with desirable fruit traits. This evaluation study can facilitate breeders and growers to have disease-resistant papaya plants with desired fruit trait.