The melon Fom‐1–Prv resistance gene pair: Correlated spatial expression and interaction with a viral protein

Abstract

The head‐to‐head oriented pair of melon resistance genes, Fom‐1 and Prv, control resistance to Fusarium oxysporum races 0 and 2 and papaya ringspot virus (PRSV), respectively. They encode, via several RNA splice variants, TIR‐NBS‐LRR proteins, and Prv has a C‐terminal extra domain with a second NBS homologous sequence. In other systems, paired R‐proteins were shown to operate by “labor division,” with one protein having an extra integrated domain that directly binds the pathogen's Avr factor, and the second protein executing the defense response. We report that the expression of the two genes in two pairs of near‐isogenic lines was higher in the resistant isoline and inducible by F. oxysporum race 2 but not by PRSV. The intergenic DNA region separating the coding sequences of the two genes acted as a bi‐directional promoter and drove GUS expression in transgenic melon roots and transgenic tobacco plants. Expression of both genes was strong in melon root tips, around the root vascular cylinder, and the phloem and xylem parenchyma of tobacco stems and petioles. The pattern of GUS expression suggests coordinated expression of the two genes. In agreement with the above model, Prv's extra domain was shown to interact with the cylindrical inclusion protein of PRSV both in yeast cells and in planta.

Plant Synthetic Promoters

“…Despite these limitations, studies on plant synthetic promoters provide valuable information concerning the regulatory mechanisms controlling gene expression in complex traits, enabling the regulation of metabolic pathway activity [28,50,78]. Moreover, of particular importance is research on plant bidirectional and orthogonal expression systems, providing solutions to problems associated with the coordinated and controlled expression of stacked genes as well as decreasing the exposition to homologous DNA sequences [28,78,79]. Besides the putative practical applications, studies on plant synthetic promoters are often performed on the whole genome scale, supported by advanced machine and deep learning algorithms.…”