Micronutrient deficiencies in African soils and the human nutritional nexus: opportunities with staple crops.

A synthesis of available agronomic datasets and peer-reviewed scientific literature was conducted to: (1) assess the status of micronutrients in sub-Saharan Africa (SSA) arable soils, (2) improve the understanding of the relations between soil quality/management and crop nutritional quality and (3) evaluate the potential profitability of application of secondary and micronutrients to key food crops in SSA, namely maize (Zea mays L.), beans (Phaseolus spp. and Vicia faba L.), wheat (Triticum aestivum L.) and rice (Oryza sativa L.). We found that there is evidence of widespread but varying micronutrient deficiencies in SSA arable soils and that simultaneous deficiencies of multiple elements (co-occurrence) are prevalent. Zinc (Zn) predominates the list of micronutrients that are deficient in SSA arable soils. Boron (B), iron (Fe), molybdenum (Mo) and copper (Cu) deficiencies are also common. Micronutrient fertilization/agronomic biofortification increases micronutrient concentrations in edible plant organs, and it was profitable to apply fertilizers containing micronutrient elements in 60-80% of the cases. However, both the plant nutritional quality and profit had large variations. Possible causes of this variation may be differences in crop species and cultivars, fertilizer type and application methods, climate and initial soil conditions, and soil chemistry effects on nutrient availability for crop uptake. Therefore, micronutrient use efficiency can be improved by adapting the rates and types of fertilizers to site-specific soil and management conditions. To make region-wide nutritional changes using agronomic biofortification, major policy interventions are needed.

Characterization of Seedling Infection Types and Adult Plant Infection Responses of Monogenic Sr Gene Lines to Race TTKS of Puccinia graminis f. sp. tritici.

Stem rust, caused by Puccinia graminis f. sp. tritici, historically was one of the most destructive diseases of wheat and barley. The disease has been under effective control worldwide through the widespread use of host resistance. A number of stem rust resistance genes in wheat have been characterized for their reactions to specific races of P. graminis f. sp. tritici. Adult plant responses to race TTKS (also known as Ug99) of monogenic lines for Sr genes, a direct measurement of the effectiveness for a given gene, have not been investigated to any extent. This report summarizes adult plant infection responses and seedling infection types for monogenic lines of designated Sr genes challenged with race TTKS. High infection types at the seedling stage and susceptible infection responses in adult plants were observed on monogenic lines carrying Sr5, 6, 7a, 7b, 8a, 8b, 9a, 9b, 9d, 9g, 10, 11, 12, 15, 16, 17, 18, 19, 20, 23, 30, 31, 34, 38, and Wld-1. Monogenic lines of resistance genes Sr13, 22, 24, 25, 26, 27, 28, 32, 33, 35, 36, 37, 39, 40, 44, Tmp, and Tt-3 were effective against TTKS both at the seedling and adult plant stages. The low infection types to race TTKS observed for these resistance genes corresponded to the expected low infections of these genes to other incompatible races of P. graminis f. sp. tritici. The level of resistance conferred by these genes at the adult plant stage varied between highly resistant to moderately susceptible. The results from this study were inconclusive for determining the effectiveness of resistance genes Sr9e, 14, 21, and 29 against race TTKS. The understanding of the effectiveness of individual Sr genes against race TTKS will facilitate the utilization of these genes in breeding for stem rust resistance in wheat.

The Spread of Stem Rust Caused by Puccinia graminis f. sp. tritici, with Virulence on Sr31 in Wheat in Eastern Africa.

Stem rust resistance in wheat cultivars with Sr31 has been effective and durable worldwide for more than 30 years. Isolates of Puccinia graminis f. sp. tritici with virulence to Sr31 were detected in Uganda in 1999 (1). During 2003 and 2004, a majority of current Kenyan cultivars and a large portion of CIMMYT wheat germplasm with gene Sr31 planted in Kenya were susceptible to stem rust. Six isolates collected during 2004 at different locations in Kenya were tested for virulence on the 16 North American stem rust race differentials with the following Sr genes: Sr5, 6, 7b, 8a, 9a, 9b, 9d, 9e, 9g, 10, 11, 17, 21, 30, 36, and Tmp. An extended set of designated Sr genes (Sr13, 19, 22, 24, 25, 26, 29, 31, 32, 33, 35, 37, 39, 40, 44, and Wld-1) was also tested at the seedling stage. An isolate from Uganda collected in 1999 with virulence on Sr31 was used for comparison. Urediniospores suspended in a lightweight mineral oil were inoculated onto 7-day-old seedlings. Inoculated plants were placed in a dew chamber for 14 h at 18°C in the dark and then for an additional period of 3 to 4 h placed under fluorescent light. Plants were incubated in a greenhouse at 18 ± 2°C with a photoperiod of 16 h. Infection types (IT), described by Stakman et al. (3), were assessed after 14 days postinoculation. All isolates from Kenya exhibited a low infection type (IT 0) on line W2691SrTt-1 (donor of Sr36), a low infection type (IT 2) on cv. Triumph 64 (donor of SrTmp), and high infection types (IT 3 or 4) on all other lines in the differential set (2); thus these isolates were keyed to race TTKS. The virulence pattern of the isolate collected in 1999 from Uganda was identical to that from Kenya on the differential set and on the extended set of designated Sr genes. In this study, these isolates produced a high infection type (IT 3) on Einkorn and CnSSr21Tm (a derivative of Triticum monococcum in Chinese Spring background), two sources of Sr21 used in our study, whereas the isolate with Sr31-virulence from Uganda in 1999 was reported to be avirulent on Sr21 (1). These isolates produced high infection types on single gene lines with Sr31 and winter wheat cvs. Custer, Foster, GA-Dozier, Patton, and Pioneer 26R61, which were known to carry the 1BL.1RS translocation with Sr31. These isolates were also virulent on SrWld-1, a gene used in spring wheat for its resistance to North American stem rust isolates. In addition to Sr36 and SrTmp, other stem rust resistance genes that were effective against TTKS at the seedling stage include Sr13, 22, 24, 25, 26, 27, 29, 32, 33, 35, 37, 39, 40, and 44. Cultivars, breeding germplasm, and single gene lines are currently being evaluated for adult plant reaction in Kenya. Results from this study indicated that stem rust isolates with virulence on Sr31 are now wide spread in the Eastern Africa highlands and pose a threat to wheat production in the region, as well as in other wheat production areas where Sr31 resistance is important. A rapid deployment of effective resistance genes to this race in breeding programs throughout Eastern Africa and Asia is needed to reduce this threat. References: (1) Z. A. Pretorius et al. Plant Dis. 84:203, 2000. (2) A. P. Roelfs and J. W. Martens. Phytopathology 78:526, 1988. (3) E. C. Stakman et al. U.S. Department of Agriculture. ARS E-617, 1962.

Kenya explores new ways of producing literacy materials for basic education.

PIP: For most developing countries, educational innovation in the 1980s will mean making the most of meager available resources in an era of shrinking foreign aid and growing educational need. According to a 1976 survey, slightly over 1/2 of Kenya's adult population was illiterate in 1976, with illiteracy concentrated among women. By 1981, some 15,000 full-time and part-time adult literacy teachers had been recruited by the Department of Adult Education, created in 1979. Since 1979, primers have been developed for the adult education program in only 15 of the more than 40 indigenous languages. In a search for ways to provide appropriate adult learning materials, pilot projects were begun in 2 districts, Meru and Kisumu. About 30 participants attended a 2-week workshop in Meru in 1980 to discuss curriculum for the low-cost literacy materials project, and the facilitators learned new techniques to pass on to the teachers. In early 1981, workshops to train teachers in low-cost materials production techniques were held in the 2 districts. About 290 teachers in Meru and 75 in Kisumu underwent training in screening techniques to determine learners' interests, exploring locally available resources for teaching aids, producing, and pretesting materials, and operating simple reproduction equipment. The workshops blended theory and practical work and were responsive to evaluation results. The projects were later expanded to the whole country, and it is hoped that by late 1983 all districts will have been covered and an evaluation carried out. The project experience has demonstrated that Third World countries do not have to be dependent on modern educational technology. Low-cost print is 1 way of supplying a technology appropriate in both cost and in meeting local needs.^ieng