PROF. MUTITU EUNICE W.

Coffee Berry Disease which affects green Arabica coffee (Coffea arabica) berries is caused by the fungus Colletotrichum kahawae and is a major problem in Arabica coffee production in African countries. Breeding for resistance to this disease is therefore to a major priority in these countries avoid intensive chemical usage for its control. Recently, microsatellite and Amplified Fragment Length Polymorphisms (AFLP) markers for a gene conferring resistance to the disease were identified and mapped onto the chromosomal region carrying the gene. To improve the repeatability of the AFLP markers, four of the marker bands were selected for cloning and sequencing to facilitate specific primers to be designed. Three of the resultant primers did not amplify products that exhibited polymorphism characteristic of the parent AFLP bands; but one primer pair amplified a product that dominantly identified the presence of the parent AFLP marker at an optimum temperature of 62°C followed by electrophoresis in agarose. The reliability of the designed primers was confirmed by analysis in 95 plants from a F2 population previously used to map the chromosomal fragment carrying the resistance. The importance of the results in enhancing the utility of the parent AFLP marker in relation to analytical costs and position on the chromosomal fragment is discussed.

Tomato is attacked by several plant parasitic nematodes but root-knot nematodes are the most devastating and cause considerable losses in Kenya. Studies were undertaken under greenhouse and field conditions to determine the suppressiveness of a wide range of plant species to root-knot (Meloidogyne spp.) nematodes. Potted plants were inoculated with 6000 eggs and /or juveniles while the field experiments were in nematode infested fields. Among the plants tested, Tagetes patula, Gossypium hirsutum, Desmodium uncinatum, Chloris gayana, Zea mays, Alstroemeria sp., Capsicum annuum, Crotalaria juncea, Arachis hypogaea, Sorghum bicolor, Tithonia diversifolia and Pennisetum purpureum were rated as poor hosts with galling and egg mass indices ranging from 0 to 3. High galling and egg mass indices ranging from 7-9 were recorded on Lablab purpureus, Coriandum, sativum, Statice sp., Brassica oleracea var. gloria, Helianthus annuus, Vigna subterranea while Muguna pruriens, Lactuca sativa, Allium ampeloprasum, Sesamum indicum, Allium cepa, Onnis sp., Brassica Oleracea Var. chinensis, Asparagus sp., Brassica oleracea var. botrytis, Ornithogolum arabicum. Tuberose sp. and Chrysanthemum indicum, were rated moderately resistant with galling and egg mass indices ranging from 3 to 6. Damage by nematodes was significantly (P=0.05) reduced in tomato planted after sweetcorn or in sweetcorn with Tagetes patula, Crotalaria juncea, Sorghum bicolor and Asparagus sp. in the field. This study shows that despite the fact that Meloidogyne spp. have wide host ranges, there is a wide range of economically important plants from which suitable candidates can be selected for use as rotation or interplants in their management.