Micropropagation of Begonia and a study of genome stability in Begonia rex

The development of procedures and media for the micropropagation of B. rex are described. Media for the production of plantlets from a number of other Begonia hybrids are also provided. Growth analysis data is given for plants produced in vivo from leaf cuttings and in vitro from mature leaf petioles and immature leaves derived from singly and multiply recycled axenic plantlets. No significant difference was found in phenotype or quantitative vegetative characters for any of the populations assessed. The results presented from studies on the development of broad spectrum media for the propagation of a number of B. rex cultivars using axenic leaf explants on factorial combinations of hormones illustrate the major influence played by the genotype on explant response in vitro and suggest media on which a range of B. rex cultivars may be propagated. Procedures for in vitro irradiation and colchicine treatments to destabilize the B. rex genome have also been described. Variants produced from these treatments indicate the utility of in vitro procedures for the expression of induced somatic variation. Colour variants produced from irradiation treatment have been cultured and prove stable. Polyploids produced as variants from irradiation treatment have been subcultured but prove unstable. Media for the induction and proliferation of callus are outlined. The influence of callus subculture and aging on the stability of the B. rex genome is assessed by chromosomal analysis of cells, in vitro and in regenerants. The B. rex genome is destabilized in callus culture but attenuation of variation occurs on regeneration. Diploid cell lines are maintained in callus subcultures and supplementation of regenerative media with high cytokinin concentrations, casein hydrolysate or adenine failed to produce variants. Callus aging however resulted in the production of polyploids. The presence and expression of pre-existing somatic variation in B. rex pith and root tissue is assessed and polyploids have been produced from pith tissues cultured in vitro. The stability of the B. rex genome and the application of tissue culture to micropropagation and breeding of B. rex are discussed.

Fundamental studies on the application of enzymes when brewing with unmalted oats and sorghum

The use of unmalted oats or sorghum in brewing has great potential for creating new beer types/flavors and saving costs. However, the substitution of barley malt with oat or sorghum adjunct is not only innovative but also challenging due to their specific grain characteristics. The overall objectives of this Ph.D. project were: 1) to investigate the impact of various types and levels of oats or sorghum on the quality/processability of mashes, worts, and beers; 2) to provide solutions as regards the application of industrial enzymes to overcome potential brewing problems. For these purposes, a highly precise rheological method using a controlled stress rheometer was developed and successfully applied as a tool for optimizing enzyme additions and process parameters. Further, eight different oat cultivars were compared in terms of their suitability as brewing adjuncts and two very promising types identified. In another study, the limitations of barley malt enzymes and the benefits of the application of industrial enzymes in high-gravity brewing with oats were determined. It is recommended to add enzymes to high-gravity mashes when substituting 30% or more barley malt with oats in order to prevent filtration and fermentation problems. Pilot-scale brewing trials using 10–40% unmalted oats revealed that the sensory quality of oat beers improved with increasing adjunct level. In addition, commercially available oat and sorghum flours were implemented into brewing. The use of up to 70% oat flour and 50% sorghum flour, respectively, is not only technically feasible but also economically beneficial. In a further study on sorghum was demonstrated that the optimization of industrial mashing enzymes has great potential for reducing beer production costs. A comparison of the brewing performance of red Italian and white Nigerian sorghum clearly showed that European grown sorghum is suitable for brewing purposes; 40% red sorghum beers were even found to be very low in gluten.

Profiling phytochemical and nutritional components of potato

Potatoes (Solanum Tuberosum L.) contain secondary metabolites that may have an impact on human health. The aim of this study was to assess the levels of some of these compounds in a wide range of varieties, including rare, heritage and commercial cultivars. Vitamin C, total carotenoids, phenolics, flavonoids, antioxidant activity and glycoalkaloids were determined, using spectroscopy and chromatography, in the skin and flesh of tubers grown in field trials. Transcript levels of key synthetic enzymes were assessed by qPCR. Accumulation of selected metabolites was higher in the skin than in the flesh of tubers, except ascorbate, which was undetected in the skin. Differences were on average 2.5 to 3-fold for carotenoids, 6-fold for phenolics, 15 to 16-fold for flavonoids, 21-fold for glycoalkaloids and 9 to 10-fold for antioxidant activity. Higher contents of carotenoids were associated with yellow skin or flesh, and higher values of phenolics, flavonoids and antioxidant activity with blue flesh. Variety ‘Burren’ had maxima values of carotenoids in skin and flesh, variety ‘Nicola’ of ascorbate, variety ‘Congo’ of phenolics, flavonoids and antioxidant activity in both tissues, except antioxidant activity in the skin, which was higher in ‘Edzell Blue’. Varieties ‘May Queen’ and ‘International Kidney’ had highest glycoalkaloid content in skin and flesh respectively. The effect of the environment was diverse: year of cultivation was significant for all metabolites, but site of cultivation was not for carotenoids and glycoalkaloids. Levels of expression of phenylalanine ammonia-lyase and chalcone synthase were higher in varieties accumulating high contents of phenolic compounds. However, levels of expression of phytoene synthase and L-galactono-1,4-lactone dehydrogenase were not different between varieties showing contrasting levels of carotenoids and ascorbate respectively. This work will help identify varieties that could be marketed as healthier and the most suitable varieties for extraction of high-value metabolites such as glycoalkaloids.

Hypoallergenic legume crops and food allergy: factors affecting feasibility and risk.

Currently, the sole strategy for managing food hypersensitivity involves strict avoidance of the trigger. Several alternate strategies for the treatment of food allergies are currently under study. Also being explored is the process of eliminating allergenic proteins from crop plants. Legumes are a rich source of protein and are an essential component of the human diet. Unfortunately, legumes, including soybean and peanut, are also common sources of food allergens. Four protein families and superfamilies account for the majority of legume allergens, which include storage proteins of seeds (cupins and prolamins), profilins, and the larger group of pathogenesis-related proteins. Two strategies have been used to produce hypoallergenic legume crops: (1) germplasm lines are screened for the absence or reduced content of specific allergenic proteins and (2) genetic transformation is used to silence native genes encoding allergenic proteins. Both approaches have been successful in producing cultivars of soybeans and peanuts with reduced allergenic proteins. However, it is unknown whether the cultivars are actually hypoallergenic to those with sensitivity. This review describes efforts to produce hypoallergenic cultivars of soybean and peanut and discusses the challenges that need to be overcome before such products could be available in the marketplace.

Densidad de siembra y fertilización nitrogenada en trigo : 1-cultivares Marcos Juárez INTA y Norkinpan 70

p.9-16

Biología y demografía de Brevicoryne brassicae (L.) (Homoptera: Aphididae) sobre cuatro cultivares de Brassica oleracea L.

p.87-91

Respuesta fotoperiódica de tres cultivares de lino (Linum usitatissimum L.)

p.265-270

Reacción en plántula a oidio Blumeria graminis f. sp. tritici de cultivares de trigo tetraploide, cultivares diferenciales y especies emparentadas con trigo

p.111-117

Generación del rendimiento de okra : comparación de dos cultivares en dos fechas de siembra

p.207-212

Introgresión diferencial de los genes Rht1 y Rht2 en cultivares de trigo pan en las distintas subregiones trigueras argentinas

p.107-113

Análisis genético del cromosoma 5A en dos variedades de trigo

p.199-202

Componentes del rendimiento en cultivares de soja del grupo V con distinto hábito de crecimiento

p.201-206

Variabilidad y evolución del rendimiento en cultivares argentinos de maíz duro

p.125-132

Evaluación del contenido mineral en seis cultivares de zanahoria (Daucus carota L.)

p.69-74

Comportamiento de cultivares de soja para consumo humano como grano verde

p.183-192