Metabolite database for root,tuber, and banana crops to facilitate modern breeding in understudied crops

Roots, tubers, and bananas (RTB) are vital staples for food security in the world's poorest nations. A major constraint to current RTB breeding programmes is limited knowledge on the available diversity due to lack of efficient germplasm characterization and structure. In recent years large‐scale efforts have begun to elucidate the genetic and phenotypic diversity of germplasm collections and populations and, yet, biochemical measurements have often been overlooked despite metabolite composition being directly associated with agronomic and consumer traits. Here we present a compound database and concentration range for metabolites detected in the major RTB crops: banana (Musa spp.), cassava (Manihot esculenta), potato (Solanum tuberosum), sweet potato (Ipomoea batatas), and yam (Dioscorea spp.), following metabolomics‐based diversity screening of global collections held within the CGIAR institutes. The dataset including 711 chemical features provides a valuable resource regarding the comparative biochemical composition of each RTB crop and highlights the potential diversity available for incorporation into crop improvement programmes. Particularly, the tropical crops cassava, sweet potato and banana displayed more complex compositional metabolite profiles with representations of up to 22 chemical classes (unknowns excluded) than that of potato, for which only metabolites from 10 chemical classes were detected. Additionally, over 20% of biochemical signatures remained unidentified for every crop analyzed. Integration of metabolomics with the on‐going genomic and phenotypic studies will enhance ’omics‐wide associations of molecular signatures with agronomic and consumer traits via easily quantifiable biochemical markers to aid gene discovery and functional characterization.     

Synergism of cellulase,pectinase and xylanase on hydrolyzing differently pretreated sweet potato residues

Abstract

The synergism of cellulase (C), pectinase (P), and xylanase (X) for the saccharification of sweet potato residues (SPR) was investigated. The removal of starch from SPR was easily achieved by using amylase, but the cellulose conversion of de-starched SPR was relatively low, thus dilute H₂SO₄, NaOH, and H₂O₂ pretreatment was conducted to improve the enzymatic digestibility. The lignin content of NaOH pretreated SPR was the lowest, whereas H₂SO₄ pretreatment resulted in the lowest contents of hemicellulose and pectin. The combination of C, P, and X exhibited different sugar production patterns, C–P displayed synergistic action on glucose and galactose production from each type of SPR, C–X also exhibited synergistic effect on glucose production except when H₂SO₄ pretreated SPR was used, whereas no synergism between P–X on monosaccharide production was observed. The presence of synergism between cellulase and mixed accessory enzymes [C–(PX)] on glucose formation was determined by C–X, and the degree of synergism between C–P and C–(PX) on glucose production had a positive relationship with pectin content. The highest cellulose conversion of 96.2% was obtained from NaOH pretreated SPR using mixed enzymes comprising C, P, and X with the ratio of 8:1:1.     

The incidence of sweet potato virus disease and virus resistance of sweet potato grown in Uganda

Sweet potato virus disease (SPVD) was common (25–30% average incidences), and farmers recognised it as an important disease, in sweet potato crops in southern Mpigi, Masaka and Rakai Districts in Uganda, but SPVD was rare in Soroti and Tororo Districts. Whiteflies, which are the vector of sweet potato chlorotic stunt crinivirus (SPCSV) a component cause of SPVD, were correspondingly common on sweet potato crops in Mpigi and rare on crops in Tororo. However, aphids, which are the vectors of sweet potato feathery mottle potyvirus (SPFMV), the other component cause of SPVD, were not found colonising sweet potato crops, and itinerant alate aphids may be the means of transmission. Different sweet potato cultivars were predominant in the different districts surveyed and four local cultivars obtained from Kanoni in S. Mpigi, where whiteflies and SPVD were common, were more resistant to SPVD than four cultivars from Busia in Tororo District, where whiteflies and SPVD were rare. However, nationally released cultivars were even more resistant than the local cultivars from Kanoni. Yield results and interviews with farmers indicated that farmers in S. Mpigi were making compromises in their choice of cultivars to grow, some key factors being SPVD susceptibility, and the yield, taste, and marketability, duration of harvest and in-ground storability of the storage roots. These compromises need to be included in an assessment of yield losses attributable to SPVD.     

Experimental archaeology gardens assessing the productivity of ancient Māori cultivars of sweet potato, Ipomoea batatas [L.] Lam. in New Zealand

This paper presents estimates of yield for effort of the cultivar, ‘Taputini,’ which is sweet potato that was eaten by the Māori of New Zealand before European contact in the 18th century. The two experimental archaeology gardens were planted at sites on either side of Cook Strait: the one with clay soils is on the South Island at Robin Hood Bay; the one with sandy soils is at Whatarangi on the North Island. The records of labor input required to cultivate these gardens over seven years for Robin Hood Bay and six years for Whatarangi compared with crop yields provide data on the economics of pre-European kũmara gardening. Also reported are some of the properties of the soil. These gardens produced an average of 12 metric tons (1,000 kilograms=1 metric ton) per hectare (ha), which is not much less than contemporary yields for modern cultivars and 3 to 4 times most previous estimates of pre-European production.     

Formation of cluster roots and mycorrhizal status of Comptonia peregrina and Myrica pensylvanica in Maine, USA

Extent of cluster (proteoid) root formation in the field was examined in relation to availability of P and successional status of the site in two actinorhizal, N₂-fixing shrubs. Comptonia peregrina (L.) Coult. and Myrica pensylvanica Loisel. In C. peregrina cluster roots were present at all 13 sites and comprised between 0.2 and 19% of total fine root dry weight. Cluster root formation was most extensive at recently disturbed sites and was negatively correlated with cover of associated woody species (r =−0.85), litter depth (r =−0.81) and available (extractable) soil P (r =−0.75). In M. pensylvanica cluster roots were present at all 11 sites and comprised between 6 and 20% of total fine root dry weight. On mineral soils (n = 6), extent of cluster root formation was negatively correlated (r =−0.86) with cover of associated woody species and with litter depth (r =−0.78; P = 0.07). Comptonia peregrina and M. pensylvanica lack functional mycorrhizae at these sites because only intracellular infections were found and these lacked arbuscules. None of 22 non-N₂-fixing, dominant woody species associated with C. peregrina and M. pensylvanica formed cluster roots. Cluster roots probably allow C. peregrina and M. pensylvanica to obtain sufficient P from nutrient-poor soils in the absence of functional mycorrhizae. Extensive cluster root formation on disturbed, early successional sites may aid these species in colonizing these sites because they have to form only one symbiosis (with Frankia ) and not two (with Frankia and a mycorrhizal fungus).     

Diphyllobothrium latum infection after eating domestic salmon flesh.

Diphyllobothrium latum infection in human is not common in Korea and only thirty seven cases have been reported since 1921. We report two cases of fish tapeworm infection after ingestion of raw cherry salmon (Oncorhynchus masou) caught in the domestic river. Among four family members who ate together raw salmon flesh six months ago, just two, mother and daughter, were infected. It is our expectation that the salmon associated tapeworm infections would be enlisted as one of the major parasitic problems with the growing consumption of salmon in Korea.