Production and identification of doubled haploids in tropical maize.
The production of maize doubled haploid (DH) lines is a technique commonly used by private companies, but not by Brazilian public institutions. Research on this technique is essential to develop and improve the production of DH lines grown under tropical conditions. We assessed the ability of a gynogenetic haploid inducer system to induce haploids in a tropical environment, assessed the induction rate of haploids identified using the R-navajo morphological marker, checked for interference from the generation of hybrid donors on haploid induction, measured the ability of flow cytometry, and simple sequence repeat marker techniques to identify doubled haploids. Seeds from the inducer Krasnodar Embryo Marker Synthetic (KEMS) line were sown in Ponta Grossa, PR, and Cravinhos, SP, and the plants were crossed to produce six hybrids and their F2 generations. The seeds were separated according to the R-navajo morphological marker indicator of haploidy (purple endosperm and white embryo) and germinated in a controlled environment. Chromosomal duplication was performed in seedlings selected as putative haploids. We performed subsequent confirmation of ploidy and the success of duplication using flow cytometry and SSR marker techniques. We concluded that DH lines can be obtained from hybrids crossed with the inducer KEMS line. The generation of inbred hybrids did not affect the induction rate or chromosomal duplication in haploids. The use of flow cytometry and SSR markers was effective in verifying chromosomal duplication in haploids.
Quantitative trait loci associated with resistance to gray leaf spot and grain yield in corn
A incorporacao de resistencia genetica a doencas e o aumento na produtividade de graos estao entre os principais objetivos dos programas de desenvolvimento de hibridos. A identificacao de locos de caracteres quantitativos (QTL) por meio de analises estatisticas associadas a marcadores moleculares possibilita a rapida obtencao de hibridos resistentes e produtivos. Nesta pesquisa, objetivou-se identificar locos de caracteres quantitativos (QTL) associados com resistencia a cercosporiose e com producao de graos em germoplasma de milho tropical. Foram utilizadas duas linhagens contrastantes em niveis de reacao a doenca (genotipos pertencentes a GENESEEDS - Ltda), seu hibrido F1 e a populacao segregante F2. Essas plantas foram fenotipadas quanto a resistencia a doenca e quanto a producao de graos e genotipadas com 94 marcadores de microssatelites. A associacao dos marcadores ao QTL foi realizada por meio de analises de marcas individuais, utilizando as metodologias de regressao linear e analise da maxima verossimilhanca. Observou-se que o tipo de efeito predominante no controle genetico da resistencia a cercosporiose foi o aditivo e para o controle genetico da producao de graos foi de dominância. Os marcadores microssatelites mais promissores para serem utilizados em estudos de selecao assistida para resistencia a cercosporiose sao umc2082 na posicao 4.03 e umc1117 na posicao 4.04 e para producao de graos, umc1042 e umc1058 nas posicoes 2.07 e 4.11.
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.