Biotic Stress/Applied Plant Bio


CS-18-6 - The antioxidant role of vitamin B6 in plants and fungi: More than meets the eye

Monday, July 16
4:58 PM - 5:00 PM

Biotic stress, as a result of plant-pathogen interactions, induces the accumulation of reactive oxygen species (ROS) in the cells, causing severe oxidative damage. To overcome this damage, both the host and pathogen have antioxidant systems to keep ROS production under control. Rhizoctonia solani, a necrotrophic fungal pathogen of many crops, can regulate intracellular ROS levels through antioxidant arsenals including Vitamin B6 (VB6). Gene expression studies focusing on oxidative stress responses in both the plant and the pathogen following R. solani infection are very limited. First, we identified VB6 biosynthetic machinery of R. solani as a powerful antioxidant with the ability to quench ROS, similar to glutathione s-transferase (GST). Second, we provide evidence on the involvement of R. solani VB6 genes; RsolPDX1 (KF620111.1) and RsolPDX2 (KF620112.1), in VB6 de-novo biosynthesis by yeast complementation assays. Third, we report on the co-expression of VB6 genes (PDX1, PDX2, PLR), and GST in plants and in R. solani during their interaction: I. Soybean leaves-R. solani; II. Soybeanhypocotyls-R. solani; III. Potato sprouts-R. solani. Distinct expression patterns of fungal and host antioxidant genes were correlated in necrotic tissues and their surrounding areas in each of the three pathosystems. Soybean pyridoxal reductase genes (GMPLR) and GMGST increased by 4.6 and 5.3 fold, respectively, in necrotic tissues of pathosystem I compared to controls. Rhizoctonia (RSolPLR) and soybean (GMPLR) genes were the driving antioxidant force in pathosystem II. In pathosystem III, activation of VB6 genes was tissue specific with higher expression of potato STPDX2 in necrotic tissues. We are extending our research to study whether the regulation of VB6 genes and vitamer levels in potato cultivars exhibiting different susceptibility to R. solani are genotype- dependent. Taken together, the differential expression of antioxidant genes in the host and the pathogen is an important determinant of disease outcome and pathogenicity.



Suha Jabaji, Dr. – McGill

Jamil Samsatly



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CS-18-6 - The antioxidant role of vitamin B6 in plants and fungi: More than meets the eye

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