The future of sustainable food production

Expression polymorphism at the ARPC4 locus links the actin cytoskeleton with quantitative disease resistance to Sclerotinia sclerotiorum in Arabidopsis thaliana

Quantitative disease resistance (QDR) is a form of plant immunity widespread in nature, and the only one active against broad host range fungal pathogens. The genetic determinants of QDR are complex and largely unknown, and are thought to rely partly on genes controlling plant morphology and development. We used genome-wide association mapping in Arabidopsis thaliana to identify ARPC4 as associated with QDR against the necrotrophic fungal pathogen Sclerotinia sclerotiorum. Mutants impaired in ARPC4 showed enhanced susceptibility to S. sclerotiorum, defects in the structure of the actin filaments and in their responsiveness to S. sclerotiorum. Disruption of ARPC4 also alters callose deposition and the expression of defense-related genes upon S. sclerotiorum infection. Analysis of ARPC4 diversity in A. thaliana identified one haplotype (ARPC4^R ) showing a c. 1 kbp insertion in ARPC4 regulatory region and associated with higher level of QDR. Accessions from the ARPC4^R haplotype showed enhanced ARPC4 expression upon S. sclerotiorum challenge, indicating that polymorphisms in ARPC4 regulatory region are associated with enhanced QDR. This work identifies a novel actor of plant QDR against a fungal pathogen and provides a prime example of genetic mechanisms leading to the recruitment of cell morphology processes in plant immunity.

Occupational exposure to pesticides and resultant health problems among cotton farmers of Punjab, Pakistan

Occupational exposure to pesticides and resultant health problems were assessed among 318 randomly selected cotton farmers from the two districts of Punjab, Pakistan. Heavy dependence of farmers on pesticides for pest control was reported. A large part (23.3%) of the pesticides belonged to the category highly hazardous, whereas the largest part (54.7%) belonged to the category moderately hazardous. Some of them (8%) were reported to be used on vegetables. Common working practices of high exposure risk were: the confrontation of pesticide spills in the stage of spray solution preparation (76.4%), the use of low-technology and faulty sprayers (67.9%), and spraying under inappropriate weather (46.5%). A large proportion (34%) of the farmers reported multiple intoxication symptoms by pesticide use; the most common were irritation of skin and eyes, headache, and dizziness. Nevertheless, most farmers thought these symptoms were usual; only few reported visiting the doctor. Findings clearly indicated a high level of risk exposure to pesticides among farmers of the study area, calling upon immediate interventions toward increasing awareness about alternative pest control practices with less pesticide use.