3 research outputs found
Evolution of Pectobacterium bacteriophage ΊM1 to escape two bifunctional Type III toxin-antitoxin and abortive infection systems through mutations in a single viral gene
Some bacteria, when infected by their viral parasites (bacteriophages), undergo a suicidal response that also terminates productive viral replication (abortive infection; Abi). This response can be viewed as an altruistic act protecting the uninfected bacterial clonal population. Abortive infection can occur through the action of Type III protein-RNA toxin-antitoxin (TA) systems, such as ToxINPa from the phytopathogen, Pectobacterium atrosepticum. Rare spontaneous mutants evolved in the generalized transducing phage, ΊM1, which escaped ToxINPa-mediated abortive infection in P. atrosepticum. ΊM1 is a member of the Podoviridae and member of the âKMV-like virusesâ, a subset of the T7 supergroup. Genomic sequencing of ΊM1 escape mutants revealed single-base changes which clustered in a single open reading frame. The âescapeâ gene product, M1-23, was highly toxic to the host bacterium when over-expressed, but mutations in M1-23 that enabled an escape phenotype caused M1-23 to be less toxic. M1-23 is encoded within the DNA metabolism modular section of the phage genome, and when it was over-expressed, it co-purified with the host nucleotide excision repair protein, UvrA. While the M1-23 protein interacted with UvrA in co-immunoprecipitation assays, a UvrA mutant strain still aborted ΊM1, suggesting that the interaction is not critical for the Type III TA Abi activity. Additionally, ΊM1 escaped a heterologous Type III TA system (TenpINPl) from Photorhabdus luminescens (reconstituted in P. atrosepticum) through mutations in the same protein, M1-23. The mechanistic action of M1-23 is currently unknown but further analysis of this protein could provide insights into the mode of activation of both systems
Rootstock on vine performance and wine quality of âSyrahâ under double pruning management
In the Brazilian Southeast, the production of high quality wines is attained by a new management approach called double pruning. This management changes the harvesting of wine grape (Vitis vinifera L.) from wet summer to dry winter through a two pruning procedures carried out during the year. The first pruning is done during the winter to induce a vegetative cycle (all clusters are removed) and a second pruning is done during the summer to induce the reproductive cycle. In this study, ten different rootstocks were compared in order to optimize yield and wine quality of Syrah vines conducted under autumn-winter season by double pruning approach. Syrah grapevines grafted onto âRupestris du Lotâ and âIAC 766â showed the highest pruning weight, while â110 Richterâ and â161-49 Courdecâ induced the lowest cane vigor. The average production of two seasons identified âIAC 766â, âKober 5BBâ and âRupestris du Lotâ as the most productive rootstocks. In both seasons, the grape quality was more influenced by the plant development status than by rootstocks. âSyrahâ wine from vigorous and high yielding rootstocks, âIAC 766â and âRupestris du Lotâ, showed satisfactory wine phenolic composition and alcohol/acidity balance. This study showed that vigorous rootstock increased yield without compromising grape and winter wine quality of Syrah grapevines subjected to double pruning management in the Brazilian Southeast