Integrating High throughput Sequencing into Survey Design Reveals Turnip Yellows Virus and Soybean Dwarf Virus in Pea (Pisum Sativum) in the United Kingdom

There is only limited knowledge of the presence and incidence of viruses in peas within the United Kingdom, therefore high-throughput sequencing (HTS) in combination with a bulk sampling strategy and targeted testing was used to determine the virome in cultivated pea crops. Bulks of 120 leaves collected from twenty fields from around the UK were initially tested by HTS, and presence and incidence of virus was then determined using specific real-time reverse-transcription PCR assays by testing smaller mixed-bulk size samples. This study presents the first finding of turnip yellows virus (TuYV) in peas in the UK and the first finding of soybean dwarf virus (SbDV) in the UK. While TuYV was not previously known to be present in UK peas, it was found in 13 of the 20 sites tested and was present at incidences up to 100%. Pea enation mosaic virus-1, pea enation mosaic virus-2, pea seed-borne mosaic virus, bean yellow mosaic virus, pea enation mosaic virus satellite RNA and turnip yellows virus associated RNA were also identified by HTS. Additionally, a subset of bulked samples were re-sequenced at greater depth to ascertain whether the relatively low depth of sequencing had missed any infections. In each case the same viruses were identified as had been identified using the lower sequencing depth. Sequencing of an isolate of pea seed-borne mosaic virus from 2007 also revealed the presence of TuYV and SbDV, showing that both viruses have been present in the UK for at least a decade, and represents the earliest whole genome of SbDV from Europe. This study demonstrates the potential of HTS to be used as a surveillance tool, or for crop-specific field survey, using a bulk sampling strategy combined with HTS and targeted diagnostics to indicate both presence and incidence of viruses in a crop.

Research on Detection Method of Pea Seed Vigor based on Hyperspectral Imaging Technology

Rapid and noninvasive detection methods of seed vigor, an important index to evaluate seed quality, have been the research focus in recent years. In this paper, the detection method of pea seed vigor based on hyperspectral imaging technology was researched. First, the spectral images of different vigor grade samples with artificial aging were captured, and the original spectrum was pretreated with multiple scattering correction. Secondly, SPA and PCA were used to select respective bands. Finally, PLS-DA and LS-SVM model were established to identify the seed vigor of the pea seed, based on the whole band spectrum, the characteristic bands extracted by SPA and PCA respectively. The results showed that PLS-DA and LS-SVM models are effective, but LS-SVM had better performance. Through comparison, the method using full band spectrum was more accurate, the efficiency of method using 5 characteristic bands extracted by PCA was the highest while the way of extracting the representative band by SPA was the most meaningful to this study which achieved similar accuracy to the full band with only 20 bands. The SPA-LS-SVM method afforded the recognition accuracy (100%) for modeling set and validation set used to determine the vigor of pea seeds. The overall results suggest that hyperspectral imaging technology is useful for classification of different vitality pea seeds with non-destructive manner, which can provide a basis for further development of online scoring devices

Pea seed-borne mosaic virus (PSbMV) Risk Analysis of Field Pea based on Susceptibility, Yield Loss and Seed Transmission

Pea seed-borne mosaic virus (PSbMV), a non-persistently aphid-transmitted potyvirus, has been reported in field pea (Pisum sativum L.) growing regions worldwide. In 2014, PSbMV was first identified in field peas in North Dakota. Susceptibility and yield losses attributed to PSbMV infection are influenced by viral pathotype and host genotype. Isolate ND14-1, recovered from North Dakota infected seed and identified as pathotype 4 (P4), was mechanically inoculated onto 20 field pea cultivars under greenhouse conditions. PSbMV susceptibility, number of seeds and pods per plant, yield, symptom expression, and PSbMV seed transmission rates were assessed by cultivar. A risk assessment was developed based on cultivar susceptibility, yield reduction, and PSbMV seed transmission. Risk factors were weighted based on perceived importance to commercial field pea producers. Three cultivars were classified as low risk, seven cultivars were classified as intermediate risk and ten cultivars were classified as high risk. Two of the low risk cultivars, Aragorn and Cruiser, were confirmed to be resistant to this isolate of PSbMV. Cultivar Arcadia was susceptible to PSbMV infection with mild expression of symptoms, but classified as low risk based on a low seed transmission rate and diminished yield losses. This risk assessment could prove a useful tool for growers in field pea cultivar selection where PSbMV is prevalent.

Influence of Nitrogen Sources on D-Lactic Acid Biosynthesis by Sporolactobacillus laevolacticus DSM 442 Strain

The purpose of this study was to explore the possibility of replacing an expensive yeast extract contained in the fermentation medium for D-lactic acid (D-LA, R-lactic acid) biosynthesis with an alternative nitrogen source. The screening studies were conducted under stationary conditions and showed that pea seed hydrolysate was the most beneficial substrate in the process of D-LA biosynthesis by the strain Sporolactobacillus laevolacticus DSM 442 among the used inorganic and organic nitrogen sources, waste materials, food and agricultural products. After 96 h, 75.5 g/L D-LA was obtained in batch cultures in a medium containing pea seed hydrolysate, with an average productivity of 0.79 g/L/h, yield of 75.5%, and optical purity of 99.4%. In batch cultures fed once, in a medium with an analogous composition, 122.6 g/L D-LA was obtained after 120 h, and the average yield, productivity and optical purity were 87.6%, 1.021 g/L/h, and 99.6%, respectively. Moreover, the amount of D-LA obtained in the fermentation medium enriched with the above-mentioned cheap agricultural product was similar to the amounts obtained in the medium containing yeast extract in both stationary and bioreactor cultures. Our research shows that hydrolyzed pea seeds, which belong to the legume family, may be a promising nitrogen source for the production of D-LA on an industrial scale.

Characterization and toxicity effect of leachate from municipality landfill

Leachate from Municipal Solid Waste (MSW) landfill has long known to be an environmental concern worldwide. The composition of landfill leachate may contain metals, ammonia, organics, other toxicants and carcinogens, having major environmental concern, with implications for plant, animal and human health. The pollution of soil, surface and ground water is also some of the major immediate concern related to leachate. This problem is growing at alarming rate in some of the developing countries including Ethiopia, and Adigrat happens to one such fast growing small city Ethiopia. However, in the absence of any significant relevant study for Adigrat City MSW leachate, the present work was undertaken to study the physico-chemical characterization of leachate from the Adigrat MSW leachate and investigate its toxicity effect on pea seed germination (Pisum sativum). The characterization was performed on the leachate from Adigrat MSW landfill. Subsequently, the leachate toxicity assessment on pea seed germination was also carried out. The result shows presence of several unacceptable components in the leachate that in some instance was detected at such levels that may pose environmental risk. It was also found that the low pH may add corrosiveness to any contaminated environmental components. Anions (like Cl−) and heavy metals (like Pb, Zn and Cd) detected in the leachate may also be concern for any possible environmental exposure. Additionally, the pea seed germination experiment suggests existence of such components in the leachate that possibly mask its nutritional property during germination.

β-Amyrin Synthase1 Controls the Accumulation of the Major Saponins Present in Pea (Pisum sativum)

The use of pulses as ingredients for the production of food products rich in plant proteins is increasing. However, protein fractions prepared from pea or other pulses contain significant amounts of saponins, glycosylated triterpenes which can impart an undesirable bitter taste when used as an ingredient in foodstuffs. In this paper, we describe the identification and characterization of a gene involved in saponin biosynthesis during pea seed development, by screening mutants obtained from two Pisum sativum TILLING (Targeting Induced Local Lesions in Genomes) populations in two different genetic backgrounds. The mutations studied are located in a gene designated PsBAS1 (β-amyrin synthase1) which is highly expressed in maturing pea seeds and which encodes a protein previously shown to correspond to an active β-amyrin synthase. The first allele is a nonsense mutation, while the second mutation is located in a splice site and gives rise to a mis-spliced transcript encoding a truncated, non-functional protein. The homozygous mutant seeds accumulated virtually no saponin without affecting seed nutritional or physiological quality. Interestingly, BAS1 appears to control saponin accumulation in all other tissues of the plant examined. These lines represent a first step in the development of pea varieties lacking bitterness off-flavours in their seeds. Our work also shows that TILLING populations in different genetic backgrounds represent valuable genetic resources for both crop improvement and functional genomics.