Novas evidências experimentais da resistência genética na cultivar de feijoeiro comum México 222 e validação do marcador molecular SW12

Ministério da Educação, Universidade Estadual de Maringá e à Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior.O objetivo deste estudo foi caracterizar a resistência genética da cultivar México 222 às raças 7 e 23 de Colletotrichum lindemuthianum, e validar a utilização do marcador molecular SW12 ligado ao gene de resistência Co-3. O objetivo deste estudo foi determinar a herança da resistência à antracnose usando o cruzamento entre as cultivares México 222 (R) × Michigan Dark Red Kidney (S) inoculado com a raça 7, além de investigar, por meio de testes de alelismo, a independência dos genes já caracterizados Co-1, Co-2, Co-3, Co-4, Co-5, Co-6 e Co-7. Os testes de herança realizados em indivíduos F2 do cruzamento México 222 × MDRK, inoculados com a raça 7, revelaram a existência de dois genes dominantes de resistência na cultivar México 222. Adicionalmente, os testes de alelismo nas populações F2 dos cruzamentos México 222 × Cornell 49-242 e México 222 × AB 136, inoculados com a raça 7, revelaram também a presença de dois genes em México 222. A ausência de segregação foi observada em 100 indivíduos F2 resultantes de cada um dos cruzamentos México 222 × G 2333 e México 222 × H1 line, inoculados com a raça 7, revelando a presença de alelismo. Por sua vez, a natureza da resistência de México 222 à raça 23 de C. lindemuthianum é monogênica. Os resultados permitiram concluir que México 222, G 2333 e H1 line possuem alelos de um mesmo locus que conferem resistência à raça 7 de C. lindemuthianum. O marcador molecular SW12 testado na população F2 do cruzamento Mexico 222 × Widusa revelou que este marcador está ligado ao gene Co-3 gene, em fase de acoplamento a uma distância de 5,8 cM.The aim of this study was to determine the inheritance of resistance to anthracnose using the cross between the cultivars Mexico 222 (R) × Michigan Dark Red Kidney (S) inoculated with race 7, and to investigate the independence of the genes of Mexico 222 from those previously characterized Co-1, Co-2, Co-3, Co-4, Co-5, Co-6 and Co-7 genes. The inheritance tests performed on the F2 population from Mexico MDRK × 222 cross, inoculated with race 7, revealed the existence of two dominant genes for resistance in the cultivar Mexico 222. Additionally, tests for allelism in F2 populations from Mexico 222 × Cornell 49-242 and Mexico 222 × AB 136 crosses, inoculated with race 7, also revealed the presence of two genes in Mexico 222. The absence of segregation was observed in 100 F2 individuals from each population derived from Mexico 222 × G 2333 and Mexico 222 × H1 line crosses, inoculated with race 7, revealing the presence of allelism. However, the nature of resistance Mexico 222 to race 23 of C. lindemuthianum is monogenic. The results showed that the genes of Mexico 222, G 2333 and H1 line, actually are alleles of the same locus that confers resistance to race 7 C. lindemuthianum. The molecular marker SW12 tested in the F2 population from the Mexico 222 × Widusa cross revealed that this marker is linked to Co-3 gene, in coupling phase, at a distance of 5.8 cM

Potassium Fertilization in the Production of Vegetables and Fruits

Consumption of vegetables worldwide has increased, not only by population growth but also by the trend of changes in consumers’ eating habits, making it inevitable to increase production. The consumer of vegetables has become more demanding, having to produce them in quantity and quality, as well as maintaining their supply throughout the year. Hydroponics is an alternative technique of cultivation in a protected environment, in which the nutritious solution is replaced by the nutrient solution. Among the essential mineral nutrients for plants, K stands out for its influence on quality attributes that affect the concentration of phytonutrients critical for human health. It acts as the determinants in the commercialization of vegetables, and can be found in various foods such as vegetables, and fruits. Adequate levels of this nutrient will benefit the consumer’s health and also prevent disease. Among the essential plant nutrients, K stands out for its influence on quality attributes that affect the concentration of phytonutrients critical to human health. The horticulturist should prioritize the use of potassic fertilizers with lower salt content, if possible free of chlorine and containing magnesium and sulfur. However, it is essential to remember that the high potassium content in plants can induce deficiency of calcium and magnesium

Tolerance of Plants to Toxicity Induced by Micronutrients

Micronutrient elements such as zinc, boron copper, iron, manganese, molybdenum, and chlorine are frequently responsible by the regulatory activity of the cell organelles, being nutrients that are absorbed and found in lower concentrations in plant tissues, they also contribute to supply the nutritional exigency of the plant. Study with Zea mays plants exposed to Zn toxicity + Si presented significant increases in stomatal conductance, net photosynthetic rate, transpiration rate, and water use efficiency, respectively, in comparison with treatment only with Zn. In relation to chlorophylls a, b and total and carotenoids presented non-significant increases, when compared to plants exposed to Zn toxicity. This study revealed the positive contribution of the Si on gas exchange and reduction of the negative effects provoked on chlorophylls and carotenoids in maize plants under Zn toxicity. Other results described that prolonged exposure to excessive Cu resulted in serious toxic effects on the rice seedlings. In contrast, Tre pretreatment has been shown to be beneficial in alleviating Cu toxicity, which was mainly attributed to the ability of Tre to restrict Cu uptake and accumulation to maintain Cu homeostasis, and to induce production of antioxidant and Gly enzymes to alleviate excessive Cu-triggered oxidative stress. Stress caused by the excessive supply of micronutrients to plants frequently promotes repercussions on oxidant system, inducing the overproduction of reactive oxygen species. The oxidative damage is a situation characterized by the large ROS accumulation and insufficient detoxification promoted by antioxidant enzymes, such as catalase and glutathione peroxidase. Different mechanisms have been proposed to explain the tolerance of plants to toxicity induced by micronutrients, as uses of other elements and substances, in which it can positively act with specific transporters, metal ion homeostasis and compartmentalization of micronutrients into the vacuole

Cowpea Breeding for Drought Tolerance — From Brazil to World

The aims of this chapter are to (i) present the importance of the cowpea crop, (ii) demonstrate problems related to drought, (iii) describe aspects related to flower structure and hybridization, and (iv) reveal how the genotype selection with tolerance to water deficit will promote increase of the yield in this culture. This chapter describes that Nigeria, Niger, and Brazil are the leading producers of cowpea crop worldwide, and this crop has a large influence on the economy of these countries. However, the drought problem can be frequently observed in areas with agricultural potential, with negative effects on production components and a consequent decrease of the yield in this culture. Breeding programs aimed at drought tolerance using selection strategies linked to genetic, biochemical, physiological, nutritional, and agronomic characteristics can help increase the yield and reduce losses promoted by the drought. In addition, flower structure and hybridization technique used in Núcleo de Pesquisa Vegetal Básica e Aplicada (NPVBA/UFRA) are presented, as well as populations are evaluated and plant management are explained in detail. This chapter describes the results obtained in other breeding programs aimed at drought tolerance and also explains the potential uses to increase the crop yield

Consequences of Water Deficit on Metabolism of Legumes

The aim of this chapter is (i) to define water deficit and its consequences on growth and development of higher plants; (ii) to present the interferences induced on metabolism, including gas exchange, biochemical compounds, and osmotic substances; and (iii) to explain how these alterations will affect the growth, development, and production of leguminous plants. This chapter reports that the performance in leguminous is affected by water deficiency, which can cause lower growth and development. For gas exchange, leaf relative water content, stomatal conductance, and transpiration rate suffered decrease when cultivated under water deficit. Biochemical compounds, such as soluble amino acids, soluble proteins, proline, and abscisic acid (ABA), are intensively modified after a period under water restriction. The results prove that ABA mediates actively and significantly the proline accumulation and consequent osmotic adjustment in Vigna unguiculata leaves that were induced to water deficit and rehydration

Management Practices for Insect Resistance in Bt Maize

The failure to reduce the population of a phytophagous species recognized as a key pest in a given situation usually occurs by not using the principles of Integrated Pest Management (IPM). The control of insect pests in agriculture has been done mainly through the application of chemical insecticides. However, chemical insecticides has lost effectiveness due to the selection of populations of resistant insects and cause adverse environmental effects. The main resistance management programs (IRM) strategy is the use of ‘high dose/refuge’, which involves the use of high dose of Bt protein in plants, promoting high mortality of heterozygotes associated with the planting of refuge, ie, a proportion of the crop in which it must be planted a non-Bt variety, allowing the survival of susceptible individuals. The emergence of Bt crops is an important step between the tactics available for pest control in various crops such as maize, canola, cotton and, in the near future, soybeans