Detection of gfp expression from gfp-labelled bacteria spot inoculated onto sugarcane tissues

Green fluorescent protein (GFP) as a marker gene has facilitated biological research in plant-microbe interactions. However, there is one major limiting factor in the detection of GFP in living organisms whose cells emit background autofluorescence. In this study, Herbaspirillum sp. B501gfp1 bacterial cells were spot inoculated onto 5 month-old sterile micro-propagated sugarcane tissues to detect if the GFP fluorescence expression could be distinguished from the tissue’s background fluorescence. Stem tissues and leaf sections mounted on glass slides were directly inoculated with a single touch using the tip of a syringe previously dipped into the inoculum containing 108 bacterial cells/ml. We observed that GFP fluorescence could be easily distinguished in the stem than in the leaf tissues. However, the brightness level of the fluorescence varied with time as a result of fluctuations in the bacterial celldensity. The presence of chloroplasts in the leaf tissues of sugarcane requires the use of bright GFP variants when monitoring bacteria-plant interactions using GFP labelled bacteria

Colonization ability of Herbaspirillum spp. B501gfp1 in sugarcane, a non-host plant in the presence of indigenous diazotrophic endophytes

Inoculating sugarcane with a mixture of diazotrophic endophytic bacteria has shown that they can provide substantial amount of biologically fixed nitrogen to the plant. The genera of diazotrophic endophytes previously isolated from sugarcane have been reported associating with other nonleguminousplants showing a broad host range. This study examined the colonization ability of a wild rice isolate, Herbaspirillum spp., in sugarcane plants in the presence of indigenous endophytes using two inoculum concentrations (102 and 108 bacterial cells ml-1). Internal tissue colonization was observed in plants inoculated with both the 102 and 108 B501gfp1 bacterial cells ml-1 inoculum concentrations. However, extensive colonization and higher bacterial numbers were determined only in the basal stem tissues of plants inoculated with the 108 bacterial cells ml-1

Morphological characterization of cashew (Anacardium occidentale L.) in four populations in Malawi

An assessment of the genetic diversity in cashew (Anacardium occidentale L.) would assist in planning for future selection of good high yield germplasm that will produce nuts of high quality and fetch highprices on the market. The genetic diversity and relationship among 40 accessions of cashew collected from 4 populations (Liwonde, Nkope, Kaputu and Chikwawa) was characterized using quantitative andqualitative traits. The study results have revealed similarity values between 35 to 66%. Analyses of genetic similarity based on unweighted pair group method of arithmetic averages (UPGMA) grouped the 40 accessions into 4 clusters with 14 sub-clusters and the principal component analysis revealed that apple length, apple nut ratio, nut weight, kernel weight, out turn percent and flower sex ratio accounted for most of the variation. The variation could be attributed to genetic history, ecogeographic origin andselection for desired agronomic traits by farmers. Accessions LW41, NE2, NE4, CH18 and PAL26 showed potential for selection in nut and kernel weight and out turn percent suggesting that this could be a valuable source of variation for tree improvement programme in cashew nuts. The findingssuggest availability of broad genetic base that could be exploited for future cashew selection and breeding in Malawi

Scaling up agroforestry farming systems: Lessons from the Malawi Agroforestry Extension Project

The study examined the factors affecting agroforestry technology upscaling and identified gaps in scaling up approaches of agroforestry technologies. One hundred and sixty-four farmers in Malawi Agroforestry Extension (MAFE) project districts of Mzimba, Ntcheu and Mangochi were interviewed. Logistic model was used in analysing data from the study. Results show that farmers’ extension access, perceived usefulness of agroforestry technology, main source of income, educational level of household head, and number of field plots were the main factors affecting the scaling up of the agroforestry technologies in the area. Among others, the study recommended that farmers and extension workers should be actively and jointly engaged in the design of agroforestry projects for effective upscaling and that agroforestry extension services should be promoted for farmers to perceive the usefulness of the technologies to enhance scaling up of the technology.Keywords: Malawi Agroforestry, Soil fertility, Scaling up of agroforestr

Effect of seed collection times and pretreatment methods on germination of Terminalia sericea Burch. ex DC

A nursery experiment was conducted to study the effects of seed collection times and pretreatment methods on the germination of Terminalia sericea Burch. ex DC. (Combretaceae). T. sericea is amultipurpose tree species occurring in the miombo woodlands whose seedling production is hampered by very low seed germination rate. Seeds were subjected to four treatment methods each at fourdifferent duration of exposure; soaking in hot water, immersion in concentrated sulphuric acid (95%), nicking and soaking in cold water and fire scorching. First collection was done when 60% of the fruitswere deep-green to brown while second collection was done when all fruits were purple-brown to pinkpurple. Nicking and soaking in cold water for 12 h gave the highest cumulative germination percentage(51%) for the first collection and appears to be the most feasible and suitable pretreatment method for small scale farmers than use of sulphuric acid. Soaking in hot water for 15 and 20 min and immersion inconcentrated sulphuric acid (95%) for 3 and 4 h gave poorest germination (0%). However, in the second collection, use of concentrated sulphuric acid for 2 h gave highest germination (14%) followed by nicking and soaking in cold water for 24 h (12%). Sulphuric acid is expensive, requires proper handling techniques; therefore nicking and soaking in cold water for 12 h is being recommended as a cheaper and less hazardous pretreatment method to improve germination in T. sericea

Minituber production potential of selected Potato (Solanum tuberosum L.) genotypes in different propagation media

Potato farmers in Malawi and other developing countries lack healthy and quality potato seed. This is mainly due to limited seed multiplication programmes to provide farmers with clean potato seed. A study to evaluate minituber production potential for selected genotypes in different media types would assist in planning for future selection of good high yielding varieties. It will also assist in planning for rapid seed multiplication programme of pathogen free planting materials to increase production of potato in the country. Three different propagation media (vermiculite, sand and sawdust) and seven different genotypes (two local genotypes- Magalabada and Rosita, five introduced genotypes-Up to date, Buffelspoort, Van der plank, Lady Rosetta and Bp 1 2007) were investigated. Plantlets grown on vermiculite performed better with higher mini tuber yield of 1740 g/m2 for all genotypes while 850 and 292 g/m2 in sand and sawdust, respectively. Among the genotypes ‘Up to date’ and Lady Rosetta produced more tubers of between 12 tubers/plant and 10 tubers/plant. Thus, vermiculite increases the number and size of Minitubers which is a very important step for rapid multiplication of potato seed. The study findings provide valuable information for potential genotypes and propagation media to assist in scaling up seed multiplication programmes for pathogen free planting materials. Keywords: Propagation media, genotype, potato, minituber.African Journal of Biotechnology, Vol 13(48) 4430-443