Overview of groundnuts research in Uganda: Past, present and future

The Groundnut Department at National Semi-Arid Research Resources Institute (NaSARRI) is mandated to conduct research on groundnuts (Arachis hypogaea L) in Uganda. It undertakes research aimed at cultivar development, maintenance and conservation through germplasm collection, characterization, evaluation, breeding, maintenance and generation of appropriate crop management technologies for sustained production. Most of the varieties traditionally grown by farmers in Uganda are landraces adapted more for survival than yield. Yields from such varieties average 800 kg/ha of dry pods yet yields of 3,000kg/ha have been achieved from on-station plots. Yields per hectare are low, because of a combination of factors such as unreliable rains, mostly non-irrigated cultures, traditional small-scale farming with little mechanization, outbreaks of pest infestations and diseases, the use of low-yielding seed varieties and increased and/or continued cultivation on marginal land. Political instability and the frequently unsupportive oilseed policies have also played their role in low groundnut productivity. Therefore, there is excellent potential for yield improvement. Research efforts have, since the 1920s, endeavored to breed varieties that are high yielding, resistant to major pests and diseases, tolerant to drought, high in oil content and have a short to medium maturity period, as well as to develop appropriate production packages. These efforts have resulted in the release of 14 varieties, the most recent being Igola-1, Serenut 1R, Serenut 2T, Serenut 3R and Serenut 4T. These varieties have helped to alleviate some of the production problems listed above. However, the market and field stability of those varieties, in light of emerging stresses, calls for continuous research while at the same time keeping crop improvement, quality and safety linked to practical applications. Emerging issues like aflatoxin, leafminers and biotechnology need to be addressed and incorporated into the research agenda. Deployment of novel breeding approaches like molecular breeding to complement conventional breeding would increase the efficiency of cultivar development. Additionally, to maintain or increase market share, producers and exporters need to adapt the type of groundnuts being cultivated to consumer requirements.Key words: Arachis, Breeding NaSARRI, Uganda

Banana Xanthomonas wilt: a review of the disease, management strategies and future research directions

Banana production in Eastern Africa is threatened by the presence of a new devastating bacterial disease caused by Xanthomonas vasicola pv. musacearum (formerly Xanthomonas campestris pv. musacearum). The disease has been identified in Uganda, Eastern Democratic Republic of Congo, Rwanda and Tanzania. Disease symptoms include wilting and yellowing of leaves, excretion of a yellowish bacterial ooze, premature ripening of the bunch, rotting of fruit and internal yellow discolorationof the vascular bundles. Plants are infected either by insects through the inflorescence or by soil-borne bacterial inoculum through the lower parts of the plant. Short- and long-distance transmission of thedisease mainly occurs via contaminated tools and insects, though other organisms such as birds may also be involved. Although no banana cultivar with resistance to the disease has been identified as yet,it appears that certain cultivars have mechanisms to ‘escape’ the disease. Management and control of the disease involve methods that reduce the inoculum’s density and spread of the pathogen. Removalof the male bud (de-budding) has proven to be very effective in preventing the disease incidence since the male bud appears to be the primary infection site. The economic impact of banana Xanthomonaswilt is not fully understood but its impact on food security in the region is very significant. While germplasm screening for the disease is ongoing, efforts to genetically engineer resistance in somebanana cultivars are also making good progress. This paper presents a review of the disease and management strategies that have been successful in curtailing its spread

Genetic diversity and population structure of Peronosclerospora sorghi isolates of Sorghum in Uganda

Sorghum is the third most important staple cereal crop in Uganda after maize and millet. Downy mildew disease is one of the most devastating fungal diseases which limits the production and productivity of the crop. The disease is caused by an obligate fungus, Peronosclerospora sorghi (Weston & Uppal) with varying symptoms. Information on the genetic diversity and population structure of P.sorghi in sorghum is imperative for the screening and selection for resistant genotypes and further monitoring possible mutant(s) of the pathogen. Isolates of P. sorghi infecting sorghum are difficult to discriminate when morphological descriptors are used. The use of molecular markers is efficient, and reliably precised for characterizing P. sorghi isolates. This study was undertaken to assess the level of genetic diversity and population structure that exist in P. sorghi isolates in Uganda. A total of 195 P. sorghi isolates, sampled from 13 different geographic populations from 10 different regions (agro-ecological zones) was used. Eleven (11) molecular markers, comprising of four Random amplified microsatellite (RAM) and seven (7) Inter-Simple Sequence Repeat (ISSR) markers were used in this study. The analysis of molecular variation (AMOVA) based on 11 microsatellite markers showed significant (P < 0.001) intra-population (88.9 %, PhiPT = 0.111) and inter-population (8.4 %, PhiPR = 0.083) genetic variation, while the genetic variation among regions (2.7 %, PhiRT = 0.022) was not significant. The highest genetic similarity value (0.987 = 98.7 %) was recorded between Pader and Lira populations and the lowest genetic similarity (0.913 = 91.3 %) was observed between Namutumba and Arua populations. The mean Nei's genetic diversity index (H) and Shannon Information Index (I) were 0.308 and 0.471 respectively. Seven distinct cluster groups were formed from the 195 P. sorghi isolates based on their genetic similarity. Mantel test revealed no association between genetic differentiation and geographical distance (R2 = 0.0026, p = 0.02) within the 13 geographic populations

Identification, characterization, and gene expression analysis of nucleotide binding site (NB)-type resistance gene homologues in switchgrass

Abstract Background Switchgrass (Panicum virgatum L.) is a warm-season perennial grass that can be used as a second generation bioenergy crop. However, foliar fungal pathogens, like switchgrass rust, have the potential to significantly reduce switchgrass biomass yield. Despite its importance as a prominent bioenergy crop, a genome-wide comprehensive analysis of NB-LRR disease resistance genes has yet to be performed in switchgrass. Results In this study, we used a homology-based computational approach to identify 1011 potential NB-LRR resistance gene homologs (RGHs) in the switchgrass genome (v 1.1). In addition, we identified 40 RGHs that potentially contain unique domains including major sperm protein domain, jacalin-like binding domain, calmodulin-like binding, and thioredoxin. RNA-sequencing analysis of leaf tissue from ‘Alamo’, a rust-resistant switchgrass cultivar, and ‘Dacotah’, a rust-susceptible switchgrass cultivar, identified 2634 high quality variants in the RGHs between the two cultivars. RNA-sequencing data from field-grown cultivar ‘Summer’ plants indicated that the expression of some of these RGHs was developmentally regulated. Conclusions Our results provide useful insight into the molecular structure, distribution, and expression patterns of members of the NB-LRR gene family in switchgrass. These results also provide a foundation for future work aimed at elucidating the molecular mechanisms underlying disease resistance in this important bioenergy crop

The Uganda rural farmers scheme: women’s accessibility to agricultural credit

This study investigates factors related to loan approval, disbursement, repayment, and loan rationing among 1,012 farmers in the Rural Farmers Scheme (RFS), Uganda, between 1987 and May 1995. Results indicate that women had a higher loan approval rate and loan repaid/loan borrowed ratio than men, but lower actual disbursement levels. Loan rationing among women and men was not statistically different, and no justification was found for microfinance institutions discriminating against women in giving loans based on repayment rates. A wide gap exists between loan amounts approved and disbursed. Strategies are outlined for improving the pool of women loan applicants.Loan application, Loan approval, Loan disbursement, Loan rationing, Smallholder farming, Women

Banana Xanthomonas wilt: a review of the disease, management strategies and future research directions

Banana production in Eastern Africa is threatened by the presence of a new devastating bacterial disease caused by Xanthomonas vasicola pv. musacearum (formerly Xanthomonas campestris pv. musacearum). The disease has been identified in Uganda, Eastern Democratic Republic of Congo, Rwanda and Tanzania. Disease symptoms include wilting and yellowing of leaves, excretion of a yellowish bacterial ooze, premature ripening of the bunch, rotting of fruit and internal yellow discoloration of the vascular bundles. Plants are infected either by insects through the inflorescence or by soil-borne bacterial inoculum through the lower parts of the plant. Short- and long-distance transmission of the disease mainly occurs via contaminated tools and insects, though other organisms such as birds may also be involved. Although no banana cultivar with resistance to the disease has been identified as yet, it appears that certain cultivars have mechanisms to ‘escape’ the disease. Management and control of the disease involve methods that reduce the inoculum’s density and spread of the pathogen. Removal of the male bud (de-budding) has proven to be very effective in preventing the disease incidence since the male bud appears to be the primary infection site. The economic impact of banana Xanthomonas wilt is not fully understood but its impact on food security in the region is very significant. While germplasm screening for the disease is ongoing, efforts to genetically engineer resistance in some banana cultivars are also making good progress. This paper presents a review of the disease and management strategies that have been successful in curtailing its spread