Molecular Characterization and Genetic Variation of Root-knot Nematode (Meloidogyne spp.,) in Selected Legume Production Areas of Eastern Kenya

Sequences from the species under study were closely related to sequences retrieved from sequences databases especially those sequences which were less divergent due to less substitutions, deletions and insertions. It can be concluded that SSUrDNA are useful in identification, inferring genetic diversity and phylogenetic relationships between the isolated root knot nematodes. There is need for a rapid and reliable method to identify populations of root-knot nematodes in order to design effective control programs.Root-knot nematodes are sedentary endoparasites of plant roots and the primarynematode pathogens of most cultivated crops worldwide, includinglegumes. Root- Knot Nematodes of the genus Meloidogyne is the most economically important nematode pests affecting cowpea and pigeon pea in Eastern Kenya. This study sought to identify the Meloidoigyne species of root-knot nematodes on selected legumes in Mbeere district and characterize the genetic diversity of the species using small subunit (SSU) rDNA. PCR amplifications of the extracted purified DNA were carried out using primers specific for the intergenic spacer region between the 5S and 18S ribosomal DNA and the expected size of about 720bp was obtained. Purified PCR products were then sequenced and thirteen 5S-18S rDNA sequences obtained. The sequences were aligned using CLUSTALW2, Sequence statistics, pairwise differences, and estimates of divergence were determined with MEGA5. Nucleotide diversities were estimated in DnaSPv5. Phylogenetic tree was drawn using Phylowin and edited in MEGA5. From the findings of the study it has been established that root knot nematodes affecting the cowpea and pigeon pea in Mbeere district are M. javanica, M. incognita and M. arenaria. Judging from the extent of differences in base composition biases between sequences, it was concluded that the sequences under study have not evolved with the same pattern of substitution

Agricultural Nematology in East and Southern Africa : Problems, Management Strategies and Stakeholder Linkages

This is the peer reviewed version of the following article: Herbert Talwana, et al, ‘Agricultural nematology in East and Southern Africa: problems, management strategies and stakeholder linkages’, Pest Management Science Vol. 72 (2): 226-245, February 2016, which has been published in final form at http://dx.doi.org/10.1002/ps.4104. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. © 2015 Society of Chemical Industry.By 2050, Africa’s population is projected to exceed two billion. Africa will have to increase food production more than 50% in the coming 50 years to meet the nutritional requirements of its growing population. Nowhere is the need to increase agricultural productivity more pertinent than in much of sub-Saharan Africa where it is currently static or declining. Optimal pest management will be essential, because intensification of any system creates heightened selection pressures for pests. Plant-parasitic nematodes and their damage potential are intertwined with intensified systems and can be an indicator of unsustainable practices. As soil pests, nematodes are commonly overlooked or misdiagnosed, particularly where appropriate expertise and knowledge transfer systems are meager or inadequately funded. Nematode damage to roots results in less efficient root systems that are less able to access nutrients and water, which can produce symptoms typical of water or nutrient deficiency, leading to misdiagnosis of the underlying cause. Damage in subsistence agriculture is exacerbated by growing crops on degraded soils and in areas of low water retention where strong root growth is vital. This review focuses on the current knowledge of economically important nematode pests affecting key crops, nematode control methods, and the research and development needs for sustainable management, stakeholder involvement and capacity building in the context of crop security in East and Southern Africa, especially Kenya, Tanzania, Uganda and Zimbabwe.Peer reviewe

GWAS provides biological insights into mechanisms of the parasitic plant (Striga) resistance in sorghum

Background Sorghum yields in sub-Saharan Africa (SSA) are greatly reduced by parasitic plants of the genus Striga (witchweed). Vast global sorghum genetic diversity collections, as well as the availability of modern sequencing technologies, can be potentially harnessed to effectively manage the parasite. Results We used laboratory assays – rhizotrons to screen a global sorghum diversity panel to identify new sources of resistance to Striga; determine mechanisms of resistance, and elucidate genetic loci underlying the resistance using genome-wide association studies (GWAS). New Striga resistant sorghum determined by the number, size and biomass of parasite attachments were identified. Resistance was by; i) mechanical barriers that blocked parasite entry, ii) elicitation of a hypersensitive reaction that interfered with parasite development, and iii) the inability of the parasite to develop vascular connections with hosts. Resistance genes underpinning the resistance corresponded with the resistance mechanisms and included pleiotropic drug resistance proteins that transport resistance molecules; xylanase inhibitors involved in cell wall fortification and hormonal regulators of resistance response, Ethylene Response Factors. Conclusions Our findings are of fundamental importance to developing durable and broad-spectrum resistance against Striga and have far-reaching applications in many SSA countries where Striga threatens the livelihoods of millions of smallholder farmers that rely on sorghum as a food staple

GWAS provides biological insights into mechanisms of the parasitic plant (Striga) resistance in sorghum

Abstract Background Sorghum yields in sub-Saharan Africa (SSA) are greatly reduced by parasitic plants of the genus Striga (witchweed). Vast global sorghum genetic diversity collections, as well as the availability of modern sequencing technologies, can be potentially harnessed to effectively manage the parasite. Results We used laboratory assays – rhizotrons to screen a global sorghum diversity panel to identify new sources of resistance to Striga; determine mechanisms of resistance, and elucidate genetic loci underlying the resistance using genome-wide association studies (GWAS). New Striga resistant sorghum determined by the number, size and biomass of parasite attachments were identified. Resistance was by; i) mechanical barriers that blocked parasite entry, ii) elicitation of a hypersensitive reaction that interfered with parasite development, and iii) the inability of the parasite to develop vascular connections with hosts. Resistance genes underpinning the resistance corresponded with the resistance mechanisms and included pleiotropic drug resistance proteins that transport resistance molecules; xylanase inhibitors involved in cell wall fortification and hormonal regulators of resistance response, Ethylene Response Factors. Conclusions Our findings are of fundamental importance to developing durable and broad-spectrum resistance against Striga and have far-reaching applications in many SSA countries where Striga threatens the livelihoods of millions of smallholder farmers that rely on sorghum as a food staple. </jats:sec

GWAS Provides Biological Insights into Mechanisms of the Parasitic Plant (Striga) Resistance in Sorghum

Abstract Background: Sorghum yields in sub-Saharan Africa (SSA) are greatly reduced by parasitic plants of the genus Striga (witchweed). Vast global sorghum genetic diversity collections, as well as the availability of modern sequencing technologies, can be potentially harnessed to effectively manage the parasite. Results: We used laboratory assays – rhizotrons to screen a global sorghum diversity panel to identify new sources of resistance to Striga; determine mechanisms of resistance, and elucidate genetic loci underlying the resistance using genome-wide association studies (GWAS). New Striga resistant sorghum determined by the number, size and biomass of parasite attahements were identified. In total 13 sorghum genotypes had higher or comparable resistance levels as IS9830 and N13 used as resistance checks. Resistance was by; i) mechanical barriers that blocked parasite entry, ii) elicitation of a hypersensitive reaction that interfered with parasite development, and iii) the inability of the parasite to develop vascular connections with hosts. Resistance genes underpinning the resistance corresponded with the resistance mechanisms and included pleiotropic drug resistance proteins that transport resistance molecules; xylanase inhibitors involved in cell wall fortification and hormonal regulators of resistance response, Ethylene Response Factors. Conclusions: Our findings are of fundamental importance to developing durable and broad-spectrum resistance against Striga and have far-reaching applications in many SSA countries where Striga threatens the livelihoods of millions of smallholder farmers that rely on sorghum as a food staple.</jats:p

Additional file 2 of GWAS provides biological insights into mechanisms of the parasitic plant (Striga) resistance in sorghum

Additional file 2

Additional file 4 of GWAS provides biological insights into mechanisms of the parasitic plant (Striga) resistance in sorghum

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Additional file 3 of GWAS provides biological insights into mechanisms of the parasitic plant (Striga) resistance in sorghum

Additional file 3

Additional file 1 of GWAS provides biological insights into mechanisms of the parasitic plant (Striga) resistance in sorghum

Additional file 1