The family Geminiviridae comprises a group of plant-infecting circular ssDNA viruses that severely constrain agricultural production throughout the temperate regions of the world, and are a particularly serious threat to food security in sub-Saharan Africa. While geminiviruses exhibit considerable diversity in terms of their nucleotide sequences, genome structures, host ranges and insect vectors, the best characterised and economically most important of these viruses are those in the genus Begomovirus. Whereas begomoviruses are generally considered to be either monopartite (one ssDNA component) or bipartite (two circular ssDNA components called DNA-A and DNA-B), many apparently monopartite begomoviruses are associated with additional subviral ssDNA satellite components, called alpha- (DNA-αs) or betasatellites (DNA-βs). Additionally, subgenomic molecules, also known as defective interfering (DIs) DNAs that are usually derived from the parent helper virus through deletions of parts of its genome, are also associated with bipartite and monopartite begomoviruses. The past three decades have witnessed the emergence and diversification of various new begomoviral species and associated DI DNAs, in southern Africa, East Africa, and proximal Indian Ocean islands, which today threaten important vegetable and commercial crops such as, tobacco, cassava, tomato, sweet potato, and beans. This review aims to describe what is known about these viruses and their impacts on sustainable production in this sensitive region of the world.

Soil ecosystem perturbation due to agronomic practices can negatively impact soil productivity by altering the diversity and function of soil health determinants. Currently, the influence of rice cultivation and off-season periods on the dynamics of soil health determinants is unclear. Therefore, soil enzyme activities (EAs) and bacterial community compositions in rice-cultivated fields at postharvest (PH) and after a 5-month off-season period (5mR), and fallow-fields (5-years-fallow, 5YF; 10-years-fallow, 10YF and/or one-year-fallow, 1YF) were assessed in two agroecological regions of Mozambique. EAs were mostly higher in fallow fields than in PH, with significant (p < 0.05) differences detected for β-glucosidase and acid phosphatase activities. Only β-glucosidase activity was significantly (p < 0.05) different between PH and 5mR, suggesting that β-glucosidase is responsive in the short-term. Bacterial diversity was highest in rice-cultivated soil and correlated with NO3−, NH4+ and electrical conductivity. Differentially abundant genera, such as Agromyces, Bacillus, Desulfuromonas, Gaiella, Lysobacter, Micromonospora, Norcadiodes, Rubrobacter, Solirubrobacter and Sphingomonas were mostly associated with fallow and 5mR fields, suggesting either negative effects of rice cultivation or the fallow period aided their recovery. Overall, rice cultivation and chemical parameters influenced certain EAs and shaped bacterial communities. Furthermore, the 5-month off-season period facilitates nutrient recovery and proliferation of plant-growth-promoting bacteria.

Coconut is one of the main cash crop in Mozambique, which occupied the second position after Tanzania in coconut production in Africa. Coconut production was drastically affected by the occurrence of a devastating Coconut Lethal Yellowing Disease (CLYD) epidemics, which reduced significantly the coconut yields. CLYD symptoms triggered upon phytoplasma infection, i.e. premature fruit dropping, necrosis of the inflorescence and progressive yellowing of the leaves, are used to identify infected trees. However, the diagnostic based uniquely on symptoms is not conclusive to confirm infection, and needs to be confirmed by molecular methods. In this study, three previously described reference primers for phytoplasma detection were tested on infected samples collected in Mozambique. Since those primers gave incongruent results, 20 new primer pairs targeting the 16S rDNA region, were newly designed. To evaluate their performance in detecting coconut infecting phytoplasma, 108 samples were tested and selected positive samples confirmed by sequencing. Our results showed a new primer pair more accurate and reliable compared to the reference pairs for CLYD detection in Mozambique. Moreover, the new primer pair was able to detect a new putative phytoplasma variant in Mozambique. Therefore, this study makes an important contribution to CLYD phytoplasma molecular diagnostics and its causative agent, giving insights that may be applied to the study of CLYD phytoplasma infection systems.