Change in physiological parameters and partitioning of sugar upon Papaya ringspot virus infection in Carica papaya and its wild relatives

• Published in: South African journal of botany 2022-12, Vol.151, p.466-474
• Main Authors: Vincent, Linta, Soorianathasundaram, K., Dinesh, M.R., Shivashankara, K.S., C, Vasugi
• Format: Article
• Language: English
• Subjects: Hexose sugar; Papaya; Papaya ringspot virus; Pentose sugar; Physiological parameters; Sucrose
• ISSN: 0254-6299; 1727-9321
• DOI: 10.1016/j.sajb.2022.10.033

•Papaya ringspot virus disease is the major detrimental in papaya cultivation. To understand the resistance mechanism in resistance source, which is Vasconcellea genus closely related to papaya, comparative studies of physiological parameters and partitioning of sugars were carried out.•Physiological parameters such as net photosynthetic rate, stomatal conductance and transpiration rate remained unchanged in resistant accessions; whereas, in susceptible accessions, PN and gs decreased as disease progressed and e increased upto 14 dpi and decline.•In resistant accessions, a sudden increase of sucrose at 7dpi and was declined at 14 dpi and normalized at 30 dpi. Whereas, in susceptible accessions continuous decrease of sucrose upto 30 dpi was noted. In susceptible accessions the glucose and fructose were increased at the later stage after inoculation i.e., at 30dpi, whereas, in resistant accessions these hexose sugars shooted up significantly at earlier stages of inoculation at 7dpi.•Consequent to PRSV infection, the ribose sugar decreased as the disease symptom and virus concentration escalated in susceptible accessions, though, in resistant wild accessions, elevated sudden increase was noticed and later normalized, whereas, the ribose sugar in V. goudotiana increased continuosly upon PRSV inoculation.•Consequent to PRSV infection, early increase of sorbitol was estimated in V. cauliflora, V. goudotiana, V. cundinamarcensis and Pusa Nanha; whereas, in other accessions, significant increase was noted at 30 days post inoculation.•Trehalose, a disaccharide sugar increased in susceptible accessions after 30 days of inoculation. Papaya ringspot virus-P is a major detrimental to papaya cultivation. All cultivars of Carica papaya are found to be susceptible to Papaya ringspot virus disease, meanwhile, the species in Vasconcellea gene pool possess PRSV resistance, conferred by many researchers. Inorder to understand the role of sugars and its partitioning as defence mechanism against PRSV attack, eleven accessions including susceptible cultivated varieties, intergeneric hybrids and wild relatives were inoculated and estimated physiological parameters such as photosynthetic rate (PN), stomatal conductance (gs) and transpiration rate (E) and profile of sugars in LC-MS. The results revealed that physiological parameters remained unchanged in resistant accessions; whereas, in susceptible accessions, PN and gs decreased as disease progressed and E increased upto 14 days