miR395 modulates DNA-primase-derived ToLCNDV resistance in melon plants
in an environment-dependent manner
Abstract
Climate change has favored the emergence of the Tomato leaf curl New
Delhi virus (ToLCNDV) as a threat to melon production in the
Mediterranean region. Deciphering the mechanisms regulating
melon-ToLCNDV interactions is crucial in developing resistant varieties
in the current climatic scenario. In this regard, DNA primase has
recently been proposed as a recessive resistance gene for ToLCNDV. Here,
we explored the molecular basis of ToLCNDV resistance in melon, focusing
on the DNA-primase gene and the stress-responsive miR395. Using
virus-induced gene silencing (VIGS) and transient expression assays, we
show that DNA-primase silencing reduces ToLCNDV accumulation in
susceptible plants, whereas overexpression increases the viral load in a
resistant cultivar. Computational predictions, validated by transient
expression analysis identified miR395 as a regulator of DNA-primase
expression. Next, we found that adverse environmental conditions, such
as salinity and drought, increase miR395 accumulation, downregulating
DNA-primase and enhancing ToLCNDV resistance in susceptible melon
cultivars. This study provides the first evidence that environmental
conditions directly affect geminivirus infection dynamics via
miR395-mediated DNA-primase regulation. These findings underscore the
potential of targeting DNA-primase for breeding ToLCNDV-resistant melon
varieties and highlight the environment influence on virus-host
interactions, offering insights for sustainable disease management in
crops.