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This research programme focuses on bacterial diseases of trees, both plantation and native tree species and to a lesser extent, fruit trees. We have two major research focuses – one on taxonomy and the other on pathogenicity factors exhibited by a select group of pathogens. The taxonomic research involves identifying new species using modern approaches, mainly in the Enterobacteriaceae. The majority of bacteria we have identified thus far have been opportunistic plant pathogens whilst others have been associated with plants as endophytes. This has led to a number of studies where we have attempted to understand how these opportunists can function as successful plant pathogens despite the fact that they occur in other ecological niches which are often diverse, such as in diesel fuel.

Our interest has primarily been on Pantoea ananatis and related Pantoea species, although we do have research projects on Xanthomonas spp. and Ralstonia solanacearum. P. ananatis is responsible for bacterial blight and die-back of Eucalyptus, brown stalk rot of maize and occurs on onion seed in South Africa. Our studies have centred on taxonomy and on developing rapid and reliable methods of distinguishing between the species of Pantoea. We are now expanding this research and are using a phylogenomic approach to examine this genus. Other elements currently under investigation include understanding the epidemiology and biology of primarily P. ananatis, but this has been expanded to include the other pathogens mentioned above as well. We have identified a number of pathogenicity factors in P. ananatis and this has given us some insight into its life as a phytopathogen. The approach we have used has involved both comparative and functional genomics. The pathogenicity factors investigated have included motility, Type VI secretion system, quorum sensing and exopolysaccharide production.

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Human ZR, Crous CJ, Roets F, Venter SN, Wingfield MJ, de Beer ZW. (2017) Biodiversity and ecology of flower-associated actinomycetes in different flowering stages of Protea repens. Antonie van Leeuwenhoek 10.1007/s10482-017-0942-3
De Maayer P, Aliyu H, Vikram S, Blom J, Duffy B, Cowan DA, Smits THM, Venter SN, Coutinho TA. (2017) Phylogenomic, pan-genomic, pathogenomic and evolutionary genomic insights into the agronomically relevant enterobacteria Pantoea ananatis and Pantoea stewartii. Frontiers in Microbiology 8(1755) 10.3389/fmicb.2017.01755
Beukes CW, Palmer M, Manyaka P, Chan W-Y, Avontuur JR, Van Zyl E, Huntemann M, Clum A, Pillay M, Palaniappan K, Varghese N, Mikhailova N, Stamatis D, Reddy TBK, Daum C, Shapiro N, Markowitz V, Ivanova N, Kyrpides N, Woyke T, Blom J, Whitman WB, Venter SN, Steenkamp ET. (2017) Genome data provides high support for generic boundaries in Burkholderia sensu lato. Frontiers in Microbiology 8 10.3389/fmicb.2017.01154
Venter SN, Palmer M, Beukes CW, Chan W-Y, Shin G, Van Zyl E, Seale T, Coutinho TA, Steenkamp ET. (2017) Practically delineating bacterial species with genealogical concordance. Antonie van Leeuwenhoek 10.1007/s10482-017-0869-8
Palmer M, Steenkamp ET, Coetzee MPA, Chan W-Y, Van Zyl E, De Maayer P, Coutinho TA, Blom J, Smits THM, Duffy B, Venter SN. (2017) Phylogenomic resolution of the bacterial genus Pantoea and its relationship with Erwinia and Tatumella. Antonie van Leeuwenhoek 10.1007/s10482-017-0852-4
Human ZR, Slippers B, De Beer ZW, Wingfield MJ, Venter SN. (2017) Antifungal actinomycetes associated with the pine bark beetle, Orthotomicus erosus, in South Africa. South African Journal of Science 113(1/2):2016-0215. 10.17159/sajs.2017/20160215 PDF
Weller-Stuart T, De Maayer P, Coutinho T. (2017) Pantoea ananatis: genomic insights into a versatile pathogen. Molecular Plant Pathology 10.1111/mpp.12517
Nesamari R, Coutinho TA, Roux J. (2017) Investigations into Encephalartos insect pests and diseases in South Africa identifies Phytophthora cinnamomi as a pathogen of the Modjadji cycad. Plant Pathology 10.1111/ppa.12619
Weller-Stuart T, Toth I, De Maayer P, Coutinho T. (2017) Swimming and twitching motility are essential for attachment and virulence of Pantoea ananatis in onion seedlings. Molecular Plant Pathology 10.1111/mpp.12432
Genome data provides high support for generic boundaries in Burkholderia sensu lato
Kwenda S, Motlolometsi TV, Birch PRJ, Moleleki LN. (2016) RNA-seq profiling reveals defense responses in a tolerant potato cultivar to stem infection by Pectobacterium carotovorum ssp. brasiliense. Frontiers in Plant Science 7(1905) 10.3389/fpls.2016.01905
Human ZR, Moon K, Bae M, De Beer ZW, Cha S, Wingfield MJ, Slippers B, Oh D-C, Venter SN. (2016) Antifungal Streptomyces spp. associated with the infructescences of Protea spp. in South Africa. Frontiers in Microbiology 7(1657) 10.3389/fmicb.2016.01657
Kwenda S, Birch PRJ, Moleleki LN. (2016) Genome-wide identification of potato long intergenic noncoding RNAs responsive to Pectobacterium carotovorum subspecies brasiliense infection. BMC Genomics 17(614) 10.1186/s12864-016-2967-9
Carstensen GD, Venter SN, Wingfield MJ, Coutinho TA. (2016) Two Ralstonia species associated with bacterial wilt of Eucalyptus. Plant Pathology 10.1111/ppa.12577
Sibanda S, Theron J, Shyntum DY, Moleleki LN, Coutinho TA. (2016) Characterization of two LuxI/R homologs in Pantoea ananatis LMG 2665 T. Canadian Journal of Microbiology 62(11):893-903. 10.1139/cjm-2016-0143
Beukes CW, Stepkowski T, Venter SN, Clapa T, Phalane FL, le Roux MM, Steenkamp ET. (2016) Crotalarieae and Genisteae of the South African Great Escarpment are nodulated by novel Bradyrhizobium species with unique and diverse symbiotic loci. Molecular Phylogenetics and Evolution 100:206-218. 10.1016/j.ympev.2016.04.011
Palmer M, De Maayer P, Poulsen M, Steenkamp ET, Van Zyl E, Coutinho TA, Venter SN. (2016) Draft genome sequences of Pantoea agglomerans and Pantoea vagans isolates associated with termites. Standards in Genomic Sciences 11(23) 10.1186/s40793-016-0144-z PDF
Kwenda S, Gorshkov V, Ramesh AM, Naidoo S, Rubagotti E, Birch PRJ, Moleleki LN. (2016) Discovery and profiling of small RNAs responsive to stress conditions in the plant pathogen Pectobacterium atrosepticum. BMC Genomics 17(1) 10.1186/s12864-016-2376-0
du Raan S, Coutinho TA, van der Waals JE. (2015) Cardinal temperature differences, determined in vitro, between closely related species and subspecies of pectinolytic bacteria responsible for blackleg and soft rot on potatoes. European Journal of Plant Pathology 144(2):361-369. 10.1007/s10658-015-0773-x
Steenkamp ET, van Zyl E, Beukes CW, Avontuur J, Chan W-Y, Palmer M, Mthombeni LS, Phalane FL, Sereme TK, Venter SN. (2015) Burkholderia kirstenboschensis sp. nov. nodulates papilionoid legumes indigenous to South Africa. Systematic and Applied Microbiology 38(8):545-554. 10.1016/j.syapm.2015.09.003
De Maayer P, Chan W-Y, Martin DAJ , Blom J, Venter SN, Duffy B, Cowan DA, Smits THM, Coutinho TA. (2015) Integrative conjugative elements of the ICEPan family play a potential role in Pantoea ananatis ecological diversification and antibiosis. Frontiers in Microbiology 6:576. 10.3389/fmicb.2015.00576
Nesamari R, Millar IM, Coutinho TA, Roux J. (2015) South African cycads at risk: Aulacaspis yasumatsui (Hemiptera: Coccoidea: Diaspididae) in South Africa. African Entomology 23(1):198-206.
Shyntum D, Theron J, Moleleki L, Toth I, Venter SN, Coutinho TA. (2015) Pantoea ananatis utilizes a type VI secretion system for pathogenesis and bacterial competition. Molecular Plant-Microbe Interactions 28(4):420-431. 10.1094/MPMI-07-14-0219-R
Coutinho TA, van der Westhuizen L, Roux J, McFarlane SA, Venter SN. (2015) Significant host jump of Xanthomonas vasicola from sugarcane to a Eucalyptus grandis clone in South Africa. Plant Pathology 64(3):576-581. 10.1111/ppa.12298
Weller-Stuart T, Chan W-Y, Coutinho TA, Venter SN, Smits THM, Duffy B, Goszczynska T, Cowan DA, de Maayer P. (2014) Draft genome sequences of the onion center rot pathogen Pantoea ananatis PA4 and maize brown stalk rot pathogen P. ananatis BD442. Genome Announcements 2(4) e00750-14
De Maayer P, Chan WY, Rubagotti E, Venter SN, Toth IK, Birch PR, Coutinho TA. (2014) Analysis of the Pantoea ananatis pan-genome reveals factors underlying its ability to colonize and interact with plant, insect and vertebrate hosts. BMC Genomics 15:404. 10.1186/1471-2164-15-404 PDF
Ngadze E, Coutinho TA, Icishahayo D, van der Waals JE. (2014) Effect of calcium soil amendments on phenolic compounds and soft rot resistance in potato tubers. Crop Protection 62:40-45. 10.1016/j.cropro.2014.04.009
Mitchell RG, Wingfield MJ, Steenkamp ET, Roux J, Verryn S, Coutinho TA. (2014) Comparison of the tolerance of Pinus patula seedlings and established trees to infection by Fusarium circinatum. Southern Forests 76(3):151-159. 10.2989/20702620.2014.899061 PDF
Shyntum DY, Venter SN, Moleleki LN, Toth I, Coutinho TA. (2014) Comparative genomics of type VI secretion systems in strains of Pantoea ananatis from different environments. BMC Genomics 15:163. 10.1186/1471-2164-15-163
Steenkamp ET, Makhari OM, Coutinho TA, Wingfield BD, Wingfield MJ. (2014) Evidence for a new introduction of the pitch canker fungus Fusarium circinatum in South Africa. Plant Pathology 63(3):530-538. 10.1111/ppa.12136 PDF