Title : Molecular and physiological screening of two papaya cultivars infected with Papaya Meleira Virus (PMeV)
This study aimed to evaluate the chlorophyll a fluorescence response in papaya leaves of cvs. Aliança and Calimosa, Group Solo, potentially infected by the papaya meleira virus complex (PMeV and PMeV2) at different developmental stages. Were used the chlorophyll a fluorescence technique and conventional and quantitative PCR techniques for the diagnosis and determination of the two viruses. Simultaneously, for the OJIP curves, the L and K-bands appeared mainly in samples that had the highest abundance of the virus, both PMeV and PMeV2, indicating a lower structural relationship of the PSII and imbalance between the electrons on the acceptor and donor sides of the PSII, respectively. The diagnosis of disease (sticky disease) using the RT-PCR technique confirmed the presence of PMeV and PMeV2 in all evaluated samples, both in cv. Aliança and cv. Calimosa. For the parameters of the JIP test, an increase in ABS/RC, DI0/RC and DI0/CS was observed, in addition to a reduction in RC/CS, ?R0, RE0/CS and performance indexes (PIabs and PItotal) in samples with high viral load, which points to the influence of the presence of the viral complex on the vegetative and reproductive development of papaya. Both cultivars had a reduction in electron transport efficiency in the final stages of the electron transport chain. These changes were subtler in 'Calimosa' both in the time transition of reproductive development and in the same developmental stage, 210 days after transplantation (DAT), when compared to 'Aliança'. It was possible to observe that the impact of the viral presence extended from PS II to the final stages of the electron transport chain, already in PS I. The results of this study corroborate the analysis of the kinetics of chlorophyll fluorescence in the rapid and early diagnosis of the presence of viral infection in plants and in studies of the specific plant-pathogen interaction, which, although complex, presents photosynthetic peculiarities.
What will audience learn from your presentation?
- Chlorophyll fluorescence can be used as a rapid and non-destructive diagnosis of crop health conditions
- Molecular diagnostics integrated with chlorophyll a fluorescence analysis can provide enough knowledge to avoid losses in crop productivity
- Diagnosis performed through chlorophyll a fluorescence can accelerate detection when compared to traditional late methods