Root-knot nematodes, Meloidogyne spp., adversely affect production of Coffea arabica in many coffee growing regions. Meloidogyne konaensis causes severe damage to the root systems of C. arabica cv. Typica 'Guatemala' grown in Kona, Hawaii. Infection by M. konaensis can cause wilting and yellowing of the leaves followed by defoliation and in severely infected areas, death of the tree.; A control method currently being utilized by farmers is the grafting of the nematode tolerant species. C. liberica var. dewevrei, to a C. arabica cv. Typica scion. Greenhouse experiments confirmed C. liberica's tolerance for M. konaensis infection. Vigorous, healthy roots and rapid shoot growth occurred in the presence of galls and high nematode populations. Coffea purpurea and C. canephora cv. Nemaya also had reduced M. konaensis populations in comparison to C. arabica although C. purpurea did not have the vigorous growth that was observed in C. liberica and C. canephora. Nematode numbers were variable among C. liberica and C. canephora individuals, suggesting that outcrossing had occurred.; Genetic transformation of C. arabica cv. Typica was explored as an alternative or additional control method against root-knot nematodes. Cystatin, a modified cysteine proteinase inhibitor from rice, and a cowpea trypsin inhibitor have been found to have adverse effects on nematode development and subsequently reproduction. The constructs used in this study are cystatin driven by a tubulin promoter, Tub-OcI-AD86, or cystatin linked with the cowpea trypsin inhibitor under the control of the CaMV35S promoter (35S-OcI-DeltaD86/GO/CpTI).; Leaf discs and somatic embryos obtained from tissue culture were used as the target tissue for coffee transformation. Small, immature, globular-shaped somatic embryos were the most efficient target tissue for particle bombardment whereas mature, torpedo-shaped somatic embryos were the most efficient for Agrobacterium tumefaciens-mediated transformation. Longer co-cultivation time with A. tumefaciens enhanced transformation efficiency. Nine to 14 days was the optimal duration for co-cultivation. Wounding the explant and adding acetosyringone to the bacteria culture prior to inoculation also improved efficiency. Particle bombardment was found to be the most effective transformation technique for C. arabica. More lines were regenerated and more plants within a line existed from bombarded somatic embryos.; Transgenic coffee plants were tested for resistance to M. konaensis . Nematode eggs were applied at the base of each plant according to size. Twenty-six percent of plants transformed with the nematode resistance genes were considered resistant, supporting 70% less M. konaensis than wild-type C. arabica of similar size. Twenty-two percent of transgenic plants had an increased susceptibility to M. konaensis, supporting 150% more nematodes than the wild-type.; PCR confirmed the insertion of the gene constructs in regenerated plantlets whereas quantitative RT-PCR measured the relative quantities of cystatin mRNA being produced in the roots during M. konaensis infection. Genes similar to the introduced plant proteinase inhibitors were discovered in C. arabica that may inhibit nematode development to some degree. The introduction of the nematode resistance constructs probably caused silencing of the endogenous genes in the susceptible coffee phenotypes.; Coffea arabica cv. Typica plants resistant to M. konaensis were produced through the introduction of plant proteinase inhibitor genes, cystatin and cowpea trypsin inhibitor. This management system may be an effective control method for root-knot nematodes on coffee although further long-term evaluation is necessary to confirm the durability of the resistance.
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