The heritability of resistance to early blight in diploid potatoes (Solanum tuberosum, subsp.Phureja andStenotomum)
The heritability of resistance to early blight caused byAlternaria solani (Ell. & Martin) Son was estimated for field grown, diploid potatoes at Fletcher, North Carolina in 1981. Fourteen breeding lines, selected from a random mated hybrid population ofSolanum tuberosum, subsp.phureja andstenotomum, were used. Resistance was measured as the slope obtained by regressing the logit of the disease proportion Y, measured as % defoliation, on time. A wide range of resistance was found. Narrow-sense heritability, as determined by offspring-midparent regression, on an individual plant basis, was calculated to be 0.825.
Biochemical and molecular studies of early blight disease in tomato
Tomato early blight occurs worldwide and it is prevalent wherever tomatoes are grown. Alternaria solani Sorauer, the causal agent, has been recognized as a serious foliar pathogen of tomato and there are very few cultivars which possess resistance against early blight. Alternaric acid is the major toxin of A. solani. In this study, alternaric acid and fungal culture filtrate were used as an elicitor in NDT-96 (tolerant) and GP-5 (susceptible) tomato varieties in order to study and compare their abilities to induce defense-related enzymes, viz., catalase, peroxidase, β-1,3 glucanase, phenylalanine-ammonia-lyase (PAL), chitinase and polyphenol-oxidase (PPO) along with total phenols, and total soluble proteins. NDT-96 showed a rapid induction of all these pathogenesis-related enzymes except catalase along with total phenols as compared to GP-5 with both the treatments. Differential expression of total soluble proteins revealed higher protein content in NDT-96 as compared with GP-5. A 49.48 kDa protein was observed to be absent in GP-5. In addition, 25 microsatellite markers (SSR) were screened for polymorphisms among the above mentioned two tomato varieties. Of these, SSR 286 revealed a significant polymorphic band of 108 bp in NDT-96.
The status of FAO and codex alimentarius developments on vegetable proteins
The FAO is interested in increasing world protein supplies both by advising and assisting developing countries to increase their production of staple foods and by encouraging the development of technology to produce protein concentrates both from vegetable and animal sources to supplement diets which are low in protein content. Recent revisions of the amount of protein required in the diet in relation to total per capita energy requirements and the difficulties encountered in introducing novel foods into established dietary patterns has led FAO to concentrate on increased agricultural productions in developing countries as the primary means of combatting malnutrition. In the meantime, in North America and Europe, advances in the technology of processing vegetable proteins has given highly acceptable products simulating meats which are being used as meat extenders and meat analogues. The consequent increase in vegetable protein production has revealed a need for international, agreement on standardization, and it has been agreed that this will be undertaken by the Joint FAO/WHO Food Standards’ Programme. The program operates chiefly through the Codex Alimentarius, Commission, an international governmental body, the purpose of which is to protect consumers against health hazard in food and against fraud. The Commission, which has 116 member governments, controls an intensive program of work covering the composition, labeling, additives, contaminants, pesticide residues, hygiene, sampling and analysis aspects of foods and has established a procedure which allows member governments ample opportunity to reach agreement on food standards and to accept them for incorporation into national legislation. The Codex Commission, at its 12th session, decided to establish a Committee on Vegetable Proteins with the following terms of references: “to elaborate definitions and world-wide standards for vegetable protein products deriving from soybeams, cottonseed, groundnuts, cereals and from other vegetable sources as they come into use for human consumption, and to elaborate guidelines on utilization of such vegetable protein products in the food supply system, on nutritional requirements and safety on labeling and on other aspects as may seem appropriate.” The question of which country will host the Committee is still under discussion.