الفهرس | Only 14 pages are availabe for public view |
Abstract Cereal grains have been the principal component of human diet for thousands of years and have played a major role in shaping human civilization. Around the world, rice, wheat, and maize, and to a lesser extent, sorghum and millets are important staples critical to daily survival of billions of people. More than 50%, reaches values exceeding 80% in the poorest countries, of world daily caloric intake is derived directly from cereal grain consumption (Awika, 2011). Cereals constitute about 55% of the African food basket and for every 1% increase in food prices, food expenditure in developing countries decreases by 0.75% (FAO, 2006). Egypt is amongst the highest importers of cereals in the world as it has occupied the fourth rank (16.8 million tons) of the top ten grain importers in the world (EPI, 2013) and is the largest wheat importer (Abdel-Razek, 2013; European Bank for Reconstruction and Development, 2013 and FAO, 2014). In the developing countries, the problem of competition from insect pests is further complicated with a rapid annual increase in the human population (2.5-3.0 percentage) in comparison to a 1.0 percentage increase in food production. In seeking to make improvements to cereal grain supply, an important element to consider is postharvest losses (PHLs), major donors have recently been focusing on loss reduction strategies (FAO/AfDB, 2009 and World Bank, 2010). Insect infestations have been reported as the major cause of food grain losses in most developing countries (Talukder et al., 2004). Protection of various agricultural crops against insect pests that cause severe economic damage is an issue being researched worldwide (Hilder and Boulter., 1999; Kramer et al., 2000; Flinn et al., 2006). One of many possibilities to achieve higher productivity in agricultural crops is to use pesticides for crop protection. But, pesticide residues can contaminate the environment, food and many of them are poisonous to humans and other organisms (Snedeker, 2001). Transgenic biotechnology can be utilized as an alternative choice for preservation of crops during storage from attack by insect pests using insect growth-inhibiting proteins, e.g., proteinase inhibitors (Ohtsubo and Richarson, 1992; Yoza et al., 2002 and Oppert et al., 2003). There are many biocidal proteins that occur in nature, which are potential biopesticides for stored-grain protection. One strategy involves using transgenes to control a wide range of pests. The insecticidal activity of chicken avidin protein has been known since the year 1959 when it was first reported as a toxin to the housefly, Muscadomestica (L.), when administered in the diet to larvae (Levinson and Bergmann, 1959). Avidin protein causes mortality in many species of stored-product insects by preventing the absorption of dietary biotin (Morgan et al., 1993). This gene has been incorporated into many plants and these transgenic plants showed remarkable resistant to stored products insects (Kramer et al., 2000; Burgess et al.,2002; Markwick et al.,2003; Yoza et al., 2005 and Cooper et al., 2009). The objective of this thesis was to develop transgenicwheat plants expressing the modified avidin gene, coding for a protein lethal to stored cereals insects, so can act as a biopesticide alternative to traditional chemical insecticides through the following steps: 1. Construction of the plant expression plasmid vector carrying a modifiedavidin gene as well as the selectable marker bar gene. 2. Genetic transformation of the Egyptian bread wheat cultivar (Giza 168) with this construct using biolistic gene gun. 3. Molecular analyses of the transgenic plants, to assess the presence and integration of the avidin gene and ensure its expression. 4. Challenging the avidin transgenic wheat flour with the grain weevil (Sitophilus granarius) to test their insecticidal effect. |