Analysis of RNAi strategies against migratory parasitic nematodes of banana

The main objective of the research project is to studythe potentialof inducing an effective host resistance againstmigratory endo-parasitic nematodes through RNA- mediated interferencetechnology (RNAi).The study is mainly targeted at the migratoryendo-parasitic nematodes Radopholus similis and Pratylenchus coffeae ,which are the most important root pathogens of banana in the tropics.Since these nematodes invade the roots and move inter- andintra-cellularly through the root by disintegrating the cell wall asthey move along, the invasion and subsequent establishment of thenematode inthe plant can be prevented by knocking down nematode genesthat encode cell-wall degrading enzymes (e.g ?-1, 4-endoglucanase). Inaddition to genes specific to plant-parasitic nematodes such as ?-1,4-endoglucanase, genes that affect the parasitic life of the nematodeeitherdirectly or indirectly are also being targeted for silencing. Bydownregulating genes that play important roles in the embryonic andlarval development or nematode locomotion, the complete progression ofpathogenesis can be adversely affected. Based on this hypothesis, thisstudy aims to develop an alternative control strategy against migratoryendo-parasitic nematodes by knocking down the above mentionedparasitism or housekeeping genes. To achieve these goals, dsRNA will bedelivered to nematodes through in vitro and in planta routes. Thenematodes will be subjected to in vitro RNAi by soaking with dsRNA ofselected parasitism genes of the nematodes and these treated nematodesare then used to infect a host plant to investigate specific genes thataffect nematode parasitism. As a control strategy against the migratoryendo-parasitic nematodes, we attempt to engineer host plants, mainlybanana and chick pea to produce dsRNA of the nematode s essential genesbased on the hypothesis that the in planta-produced dsRNA can triggerRNAi response in nematodes that feed on these transgenic plants.nrpages: 250status: publishe

Comparative genomics of apomictic root-knot nematodes:Hybridization, ploidy, and dynamic genome change

The Root-Knot Nematodes (RKN; genus Meloidogyne) are important plant parasites causing substantial agricultural losses. The Meloidogyne incognita group (MIG) of species, most of which are obligatory apomicts (mitotic parthenogens), are extremely polyphagous and important problems for global agriculture. While understanding the genomic basis for their variable success on different crops could benefit future agriculture, analyses of their genomes are challenging due to complex evolutionary histories that may incorporate hybridization, ploidy changes, and chromosomal fragmentation. Here we sequence 19 genomes, representing five species of key RKN collected from different geographic origins. We show that a hybrid origin that predated speciation within the MIG has resulted in each species possessing two divergent genomic copies. Additionally, the apomictic MIG species are hypotriploids, with a proportion of one genome present in a second copy. The hypotriploid proportion varies among species. The evolutionary history of the MIG genomes is revealed to be very dynamic, with non-crossover recombination both homogenising the genomic copies, and acting as a mechanism for generating divergence between species. Interestingly, the automictic MIG species M. floridensis differs from the apomict species in that it has become homozygous throughout much of its genome

Analysis of RNAi strategies against migratory parasitic nematodes of banana

The main objective of the research project is to studythe potentialof inducing an effective host resistance againstmigratory endo-parasitic nematodes through RNA- mediated interferencetechnology (RNAi).The study is mainly targeted at the migratoryendo-parasitic nematodes Radopholus similis and Pratylenchus coffeae ,which are the most important root pathogens of banana in the tropics.Since these nematodes invade the roots and move inter- andintra-cellularly through the root by disintegrating the cell wall asthey move along, the invasion and subsequent establishment of thenematode inthe plant can be prevented by knocking down nematode genesthat encode cell-wall degrading enzymes (e.g ?-1, 4-endoglucanase). Inaddition to genes specific to plant-parasitic nematodes such as ?-1,4-endoglucanase, genes that affect the parasitic life of the nematodeeitherdirectly or indirectly are also being targeted for silencing. Bydownregulating genes that play important roles in the embryonic andlarval development or nematode locomotion, the complete progression ofpathogenesis can be adversely affected. Based on this hypothesis, thisstudy aims to develop an alternative control strategy against migratoryendo-parasitic nematodes by knocking down the above mentionedparasitism or housekeeping genes. To achieve these goals, dsRNA will bedelivered to nematodes through in vitro and in planta routes. Thenematodes will be subjected to in vitro RNAi by soaking with dsRNA ofselected parasitism genes of the nematodes and these treated nematodesare then used to infect a host plant to investigate specific genes thataffect nematode parasitism. As a control strategy against the migratoryendo-parasitic nematodes, we attempt to engineer host plants, mainlybanana and chick pea to produce dsRNA of the nematode s essential genesbased on the hypothesis that the in planta-produced dsRNA can triggerRNAi response in nematodes that feed on these transgenic plants.nrpages: 250status: publishe

RNA interference in Pratylenchus coffeae: knock down of Pc-pat-10 and Pc-unc-87 impedes migration

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