No abstract

Agricultural transformation is key to poverty reduction and food security in sub-Saharan Africa (SSA). In Rwanda, this transformation has focused on shifting subsistence-based production to market-oriented farming. Over the last one decade and a half, major emphasis has been placed on the intensification of production systems, promotion of farmers' cooperatives, and enhancement of farmers' access to markets. Although the country recorded an increase in food crop commercialization, subsistence farming is still prevalent amongst smallholder farmers. Yet, in the few studies conducted on agricultural transformation, smallholder commercialization has received scanty attention. As the country aims to achieve commercialized agriculture, there is a need to understand what factors can influence farmers' decisions to participate in the output markets. This study analyses the levels of market participation and drivers of output commercialization, using a sample of 256 Common bean farmers from northern Rwanda. A double-hurdle model was used to analyse the data. Results indicated that 30% of the farmers participated in the market with an average commercialization index of 0.42. Land size, agricultural training and group membership of household head had a positive effect on households' participation to bean market. The distance to the nearest access road that can be used throughout the year reduces the probability of commercialization at household level. The degree of market participation was positively influenced by price, education level of the household head and livestock income. On the other hand, distance to key markets had a negative effect on the degree of households' commercialization. The findings of this paper show that participation in bean markets is still low, with disparities in the commercialized quantities amongst those who participate. Female-headed households were more likely to participate in bean markets, selling higher volumes than male-headed households. This gender difference suggests that bean production can be an important source of income for women smallholder farmers. The study recommends more efforts in improving road networks connecting to key markets, facilitating cross-border trade and increasing agricultural training amongst the farmers. Additionally, the use of improved inputs in bean production as well as income diversification through livestock rearing should be encouraged. All the interventions should be gender-sensitive so as not to deny women their source of livelihood through bean production and marketing.

We announce the genome sequence for Xanthomonas species strain Nyagatare, isolated from beans showing unusual disease symptoms in Rwanda. This strain represents the first sequenced genome belonging to an as-yet undescribed Xanthomonas species known as species-level clade 1. It has at least 100 kb of genomic sequence that shows little or no sequence similarity to other xanthomonads, including a unique lipopolysaccharide synthesis gene cluster. At least one genomic region appears to have been acquired from relatives of Agrobacterium or Rhizobium species. The genome encodes homologues of only three known type-three secretion system effectors: AvrBs2, XopF1 and AvrXv4. Availability of the genome sequence will facilitate development of molecular tools for detection and diagnostics for this newly discovered pathogen of beans and facilitate epidemiological investigations of a potential causal link between this pathogen and the disease outbreak.

Common bean production is constrained by different diseases the major ones being, Angular Leaf Spot (ALS), bean root rot, anthracnose, Common Bright Bacteria (CBB), Bean Common Cosaic Virus (BCMV) and Bean Common Mosaic Necrotic Virus, (BCMNV). The aim of this study was to identify new and better sources of broad resistance to both bean ALS and Root Rot diseases among nutritional bean varieties. Fifty seven varieties were planted in the screen house of CIAT Africa based at Kawanda Agricultural Research Laboratories Institute (KARL). Virulent inocula actually used at CIAT were used to test these genotypes. Different varieties were resistant to specific isolates but interestingly, only ACC 714 contained broad resistance to both Andean and MesoAmerican isolates of bean Angular Leaf Spot as well as Fusarium root rot and Pythium root rot at mean, median and mode basis. Since different nutritional bean varieties have varying levels of resistance to different pathogens, it may be possible to pyramid these resistance genes into appropriate background so as to provide durable resistance in biofortified bean genotypes higher in iron and zinc content.

Anthracnose, caused by Colletotrichum lindemuthianum, is a major disease of common bean and results in high yield loss. Due to the high degree of pathogenic variability of the fungus and the continual emergence of new races, genetic resistance in the host is not durable. Gene pyramiding using Marker Assisted Selection (MAS) is proposed as a viable approach to improve the durability of major genes conditioning resistance to anthracnose. In this study a common bean line Urugezi x AND 1062 susceptible to anthracnose but already improved for Pythium root rot resistance was improved for anthracnose resistance through a backcross breeding program. Genotypic selection was done in Rubilizi laboratory in Kigali, Rwanada whereas phenotypic selection was conducted in an anthracnose hotspot at Rwerere, a research Centre of the Rwanda Agricultural and Animal Resources Development Board (RAB). Analysis of variance for effect of bean varieties and anthracnose isolates on disease expression showed significant differences (p < 0.001) among varieties and isolates and for the interaction between isolates and varieties. Developed BC 2 F 1 plants were 41% of them resistant and 59% susceptible to anthracnose. However, the observed proportion of 26 resistants and 37 susceptible in BC 2 F 1 plants didn't fit the goodness of fit of the expected proportion of 75 resistants to 25 susceptible. Only 41% of BC 2 F 1 plants inherited the resistance genes and were phenotypically resistant. Presence of SCAR-markers, SAB3 and SBB14, in the developed resistant lines h suggested successful resistance transfer of anthracnose resistance genes.