JIP60-mediated, jasmonate- and senescence-induced molecular switch in translation toward stress and defense protein synthesis

Two closely related genes encoding the jasmonate-induced protein 60 (JIP60) were identified in the barley genome. The gene on chromosome arm 4HL encodes the previously identified protein encoded by the cDNA X66376.1. This JIP60 protein is characterized here and shown to consist of two domains: an NH ₂-terminal domain related to ribosome-inactivating proteins and a COOH-terminal domain, which displays similarity to eukaryotic translation initiation factor 4E (eIF4E). JIP60 undergoes processing in vivo, as a result of which JIP60’s COOH-terminal eIF4E domain is released and functions in recruiting a subset of cellular messengers for translation. This effect was observed for both MeJA-treated and naturally senescing plants. Because the JIP60 gene is in close proximity to several quantitative trait loci for both biotic and abiotic stress resistance, our results identify a unique target for future breeding programs. Significance Quantitative trait loci (QTLs) are major targets for plant breeders. Despite intensive efforts undertaken over the last decades, still little is known how QTLs affect plant resistance to biotic and abiotic stresses and what exact molecular markers (genes) are involved. Here we identified a gene in barley that maps to previously identified QTLs for boron sensitivity, plant height, lodging, stem breaking, days to heading, yield, seed weight, days to maturity, as well as powdery mildew and spot blotch resistance. This gene is identical to a previously described jasmonate-induced protein designated JIP60 that by virtue of its unique structure and processing is capable of reprogramming protein translation for increased stress tolerance and controlled senescence.