Impact on Physiological Parameters upon PRSV Infection in Different Genotypes of Carica papaya L. and Vasconcellea species

Abstract

Papaya is major tropical fruit gaining importance throughout the tropics and subtropics but there is a severe restriction in its production due to the serious disease known as Papaya Ring Spot Virus (PRSV-P).No papaya variety till date was identified as having durable resistance to PRSV-P; whereas several species of Vasconcellea, a close relative of papayawas reported to have heritable resistance to Papaya Ring Spot Virus. To understand these changes in physiological parameters upon PRSVinfection this study was carried out by involving six Caricapapayavarieties, two intergeneric hybrids of Carica papayaand Vasconcellea caulifloraand three Vasconcelleaspecies. The physiological parameters viz., photosynthetic rate (PN), stomatal conductance (gs) and transpiration rate (E) were measured before inoculation, and subsequently 7 days post inoculation (7 dpi) with PRSV, 14 dpi and 30 dpi. The results revealed that the photosynthetic rate and stomatal conductance were found get reduced in the susceptible genotypes viz., Arka Surya, Arka Prabhath, Red Lady and Pusa Dwarf at all the stages of observation, while in tolerant genotypes such as Pusa Nanha, TNAU papaya CO8, they initially decreased at 7 dpi but found to be raised at 14 dpi but again declined during the observation on 30 dpi. In IGH1 and IGH2, PN and gs were found to be increased at 7 dpi but decreased afterwards. In susceptible genotypes, transpiration rate was found to be increased continuously upto 14 dpi and reduced at 30 dpi. The physiological parameters did not show any significant alterations in the photosynthetic rate, stomatal conductance and transpiration rate in the three Vasconcellea species evaluated.