Fast and Sensitive Detection of Soil-Borne Cereal Mosaic Virus in Leaf Crude Extract of Durum Wheat

Soil-borne cereal mosaic virus (SBCMV) is a furovirus with rigid rod-shaped particles containing an ssRNA genome, transmitted by Polymyxa graminis Led., a plasmodiophorid that can persist in soil for up to 20 years. SBCMV was reported on common and durum wheat and it can cause yield losses of up to 70%. Detection protocols currently available are costly and time-consuming (real-time PCR) or have limited sensitivity (ELISA). To facilitate an efficient investigation of the real dispersal of SBCMV, it is necessary to develop a new detection tool with the following characteristics: no extraction steps, very fast results, and high sensitivity to allow pooling of a large number of samples. In the present work, we have developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) protocol with such characteristics, and we have compared it with real-time PCR. Our results show that the sensitivity of LAMP and real-time PCR on cDNA and RT-LAMP on crude extracts are comparable, with the obvious advantage that RT-LAMP produces results in minutes rather than hours. This paves the way for extensive field surveys, leading to a better knowledge of the impact of this virus on wheat health and yield.

Two dominant genes in barley (Hordeum vulgare L.) complementarily encode perfect resistance to Japanese soil-borne wheat mosaic virus

Japanese soil-borne wheat mosaic virus (Furovirus) is a damaging pathogen of wheat and barley. This virus can survive in the soil for several decades, so the deployment of resistant cultivars represents the only practical control measure. Here, a genetic analysis has identified two regions of the barley genome-one on chromosome 2H and the other on chromosome 3H-as harboring gene(s) encoding resistance to this virus. The joint presence of both loci, termed Jmv1 and Jmv2, made the plants essentially immune, with resistance being dominant over susceptibility at each locus. Phylogenetic analysis showed that the virus is not closely related to the type Furovirus species Soil-borne wheat mosaic virus. There was a difference between the RNA1- and RNA2-based phylogenies of the virus species in Furovirus implying the independent segregation of the virus subgenomes.

A genetic analysis of the resistance in barley to Soil-borne wheat mosaic virus

Soil-borne wheat mosaic virus (SBWMV), a ubiquitous pathogen commonly encountered in temperate regions of the Northern hemisphere, can damage a number of economically important cereal crops, notably wheat and barley. Given that the plasmodiophorid cercozoan Polymyxa graminis, which acts as the vector of SBWMV, can survive in the soil for many decades, the only feasible control measure is the deployment of resistant cultivars. Here, a quantitative trait locus (QTL) approach was taken to characterize the genetic basis of the SBWMV resistance exhibited by the barley cultivar Haruna Nijo. The analysis revealed that between 33% and 41% of the variation for the measure chosen to represent resistance was under the control of a gene(s) mapping to a region at the distal end of the short arm of chromosome 2H. In contrast to most of the genes known to encode resistance to soil-borne mosaic viruses, the allele specifying resistance was dominant over those present in a susceptible genotype.

Soil-borne wheat mosaic virus infectious clone and manipulation for gene-carrying capacity

A full-length infectious cDNA clone of soil-borne wheat mosaic virus (SBWMV; genus Furovirus; family Virgaviridae) was developed for agrobacterium delivery. The cloned virus can be agroinfiltrated to Nicotiana benthamiana for subsequent infection of wheat (Triticum aestivum, L.). The utility of the virus as a vector for gene silencing and expression was assessed through sequence insertions in multiple sites of RNA2. Virus-induced photobleaching was observed in N. benthamiana but not in wheat, despite the stability of the inserts. The SBWMV infectious clone can be used for further studies to investigate the biology of SBWMV through mutagenesis.