Expression of genes involved in the salicylic acid pathway in type h1 thioredoxin transiently silenced pepper plants during a begomovirus compatible interaction.

The type-h thioredoxins (TRXs) play a fundamental role in oxidative stress tolerance and defense responses against pathogens. In pepper plants, type-h TRXs participate in the defense mechanism against Cucumber mosaic virus. The goal of this study was to analyze the role of the CaTRXh1-cicy gene in pepper plants during compatible interaction with a DNA virus, the Euphorbia mosaic virus-Yucatan Peninsula (EuMV-YP). The effects of a transient silencing of the CaTRXh1-cicy gene in pepper plants wëre evaluated by observing the accumulation of viral DNA and the visible symptoms of pepper plants under different treatments. The accumulation of salicylic acid (SA) and the relative expression of the defense genes NPR1 and PR10 were also evaluated. Results showed that viral DNA accumulation was higher in transiently CaTRXh1-cicy silenced plants that were also infected with EuMV-YP. Symptoms in these plants were more severe compared to the non-silenced plants infected with EuMV-YP. The SA levels in the EuMV-YP-infected plants were rapidly induced at 1 h post infection (hpi) in comparison to the non-silenced plants inoculated with EuMV-YP. Additionally, in pepper plants infected with EuMV-YP, the expression of NPR1 decreased by up to 41 and 58 % at 28 days post infection (dpi) compared to the non-silenced pepper plants infected with only EuMV-YP and healthy non-inoculated pepper plants, respectively. PR10 gene expression decreased by up to 70 % at 28 dpi. Overall, the results indicate that the CaTRXh1-cicy gene participates in defense mechanisms during the compatible interaction of pepper plants with the EuMV-YP DNA virus.

Paraoxonase 1 polymorphisms and haplotypes and the risk for having offspring affected with spina bifida in Southeast Mexico.

BACKGROUND: Spina bifida (SB) is a common congenital malformation in Southeast Mexico. Parents of children with SB reside in areas with frequent pesticide spraying or have agriculture activities, suggesting potential exposure to pesticides. Paraoxonase 1 (PON1) is the responsible enzyme for deactivation of organophosphates (OP) in the central nervous system. Polymorphisms of PON1 genes influence the catalytic activity and plasma protein level of the enzyme, therefore, genotypic characterization of PON1 gene represents a potential predictor for susceptibility to OP-related effects. METHODS: The frequency of PON1 haplotypes and polymorphisms (-108CT, L55M, and Q192R) were determined in this study. A case-control study was performed to evaluate the risk for having offspring affected by SB in 152 cases and 160 control parents. Polymorphisms were determined by PCR amplification and restriction fragment length polymorphism and Real Time-PCR. Odds ratios and confidence interval 95% were estimated. RESULTS: Genotype frequencies for the three PON1 polymorphisms were distributed according to Hardy-Weinberg expectations (p > 0.05) and were significantly different between cases and controls (p < 0.05). The heterozygous CT genotype of -108CT polymorphism, the RR genotype of Q192R polymorphism, both LM and MM genotypes of L55M polymorphism, and the haplotypes 221 and 222 (for -108CT, L55M, and Q192R) were associated with the risk for having a child affected by SB (p < 0.02). The heterozygous -108CT genotype was associated only maternally, whereas the heterozygous L55M genotype was relevant only in the fathers. The RR homozygous genotype was relevant both in mothers and fathers, suggesting the importance of this substrate-specific polymorphism. CONCLUSION: Results suggest that PON1 polymorphisms are relevant risk factors for having offspring affected with SB in this population from Southeast Mexico.