A Nutrition-Sensitive Agroecology Intervention in Rural Tanzania Increases Children's Dietary Diversity and Household Food Security But Does Not Change Child Anthropometry: Results from a Cluster-Randomized Trial.

BACKGROUND: There are urgent calls for the transformation of agriculture and food systems to address human and planetary health issues. Nutrition-sensitive agriculture and agroecology promise interconnected solutions to these challenges, but evidence of their impact has been limited. OBJECTIVES: In a cluster-randomized trial (NCT02761876), we examined whether a nutrition-sensitive agroecology intervention in rural Tanzania could improve children's dietary diversity. Secondary outcomes were food insecurity and child anthropometry. We also posited that such an intervention would improve sustainable agricultural practices (e.g., agrobiodiversity, intercropping), women's empowerment (e.g., participation in decision making, time use), and women's well-being (e.g., dietary diversity, depression). METHODS: Food-insecure smallholder farmers with children aged <1 y from 20 villages in Singida, Tanzania, were invited to participate. Villages were paired and publicly randomized; control villages received the intervention after 2 y. One man and 1 woman "mentor farmer" were elected from each intervention village to lead their peers in agroecological learning on topics including legume intensification, nutrition, and women's empowerment. Impact was estimated using longitudinal difference-in-differences fixed-effects regression analyses. RESULTS: A total of 591 households (intervention: n = 296; control: n = 295) were enrolled; 90.0% were retained to study end. After 2 growing seasons, the intervention improved children's dietary diversity score by 0.57 food groups (out of 7; P < 0.01), and the percentage of children achieving minimum dietary diversity (≥4 food groups) increased by 9.9 percentage points during the postharvest season. The intervention significantly reduced household food insecurity but had no significant impact on child anthropometry. The intervention also improved a range of sustainable agriculture, women's empowerment, and women's well-being outcomes. CONCLUSIONS: The magnitude of the intervention's impacts was similar to or larger than that of other nutrition-sensitive interventions that provided more substantial inputs but were not agroecologically focused. These data suggest the untapped potential for nutrition-sensitive agroecological approaches to achieve human health while promoting sustainable agricultural practices.

Association mapping of stem rust race TTKSK resistance in US barley breeding germplasm.

KEY MESSAGE: Loci conferring resistance to the highly virulent African stem rust race TTKSK were identified in advanced barley breeding germplasm and positioned to chromosomes 5H and 7H using an association mapping approach. African races of the stem rust pathogen (Puccinia graminis f. sp. tritici) are a serious threat to barley production worldwide because of their wide virulence. To discover and characterize resistance to African stem rust race TTKSK in US barley breeding germplasm, over 3,000 lines/cultivars were assessed for resistance at the seedling stage in the greenhouse and also the adult plant stage in the field in Kenya. Only 12 (0.3 %) and 64 (2.1 %) lines exhibited a resistance level comparable to the resistant control at the seedling and adult plant stage, respectively. To map quantitative trait loci (QTL) for resistance to race TTKSK, an association mapping approach was conducted, utilizing 3,072 single nucleotide polymorphism (SNP) markers. At the seedling stage, two neighboring SNP markers (0.8 cM apart) on chromosome 7H (11_21491 and 12_30528) were found significantly associated with resistance. The most significant one found was 12_30528; thus, the resistance QTL was named Rpg-qtl-7H-12_30528. At the adult plant stage, two SNP markers on chromosome 5H (11_11355 and 12_31427) were found significantly associated with resistance. This resistance QTL was named Rpg-qtl-5H-11_11355 for the most significant marker identified. Adult plant resistance is of paramount importance for stem rust. The marker associated with Rpg-qtl-5H-11_11355 for adult plant resistance explained only a small portion of the phenotypic variation (0.02); however, this QTL reduced disease severity up to 55.0 % under low disease pressure and up to 21.1 % under heavy disease pressure. SNP marker 11_11355 will be valuable for marker-assisted selection of adult plant stem rust resistance in barley breeding.

The emergence of Ug99 races of the stem rust fungus is a threat to world wheat production.

Race Ug99 of the fungus Puccinia graminis tritici that causes stem or black rust disease on wheat was first detected in Uganda in 1998. Seven races belonging to the Ug99 lineage are now known and have spread to various wheat-growing countries in the eastern African highlands, as well as Zimbabwe, South Africa, Sudan, Yemen, and Iran. Because of the susceptibility of 90% of the wheat varieties grown worldwide, the Ug99 group of races was recognized as a major threat to wheat production and food security. Its spread, either wind-mediated or human-aided, to other countries in Africa, Asia, and beyond is evident. Screening in Kenya and Ethiopia has identified a low frequency of resistant wheat varieties and breeding materials. Identification and transfer of new sources of race-specific resistance from various wheat relatives is underway to enhance the diversity of resistance. Although new Ug99-resistant varieties that yield more than current popular varieties are being released and promoted, major efforts are required to displace current Ug99 susceptible varieties with varieties that have diverse race-specific or durable resistance and mitigate the Ug99 threat.

Identification and Evaluation of Sources of Resistance to Stem Rust Race Ug99 in Wheat.

The race Ug99 of Puccinia graminis f. sp. tritici causing stem rust disease of wheat was initially identified in Uganda in 1998. It was designated as TTKSK based on the North American nomenclature and has caused periodic losses to wheat crops in East Africa. Ug99 has recently moved out of Africa to Yemen and West Asia. The most effective approach to prevent losses from stem rust is through the deployment of resistant cultivars. More effective sources of resistance need to be identified and incorporated in the existing commercial cultivars. The first Stem Rust Resistance Screening Nursery (1stSRRSN) assembled by the International Maize and Wheat Improvement Center (CIMMYT) consisted of elite and advanced CIMMYT bread wheat lines and was evaluated for resistance to Ug99 in Njoro, Kenya for four consecutive seasons (2005 to 2007). Seedling reactions were determined in the greenhouse at the Cereal Disease Laboratory, St. Paul, MN. Two race-specific genes, Sr24 and Sr25, were found to confer resistance to Ug99, although Sr24 became ineffective to a mutant race of Ug99, TTKST, in 2007. Three previously uncharacterized genes, one each from synthetic wheat, Chinese germplasm, and other genetic backgrounds, were detected. Although 30% of the screened lines were susceptible in the seedling stage, these lines displayed various levels of adult plant resistance (APR) in the field tests. Presence of the APR gene Sr2, identified based on the pseudo-black chaff phenotype on glumes and darkened internode, was common in wheat lines with APR. The information on the resistance identified in the 1stSRRSN constitutes an important source for breeding wheat for durable resistance.