Phytophthora root rot (PRR) is the most severe and damaging disease in avocado plantations in South Africa. The causal agent, Phytophthora cinnamomi, is an oomycete that also causes disease on thousands of other plant species. The pathogen is a heterothallic species that can reproduce by sexual or asexual means. It can persist in soil or infected plant material for extended periods of time, and there is no means to eradicate this oomycete from infected areas once the pathogen has successfully established in soils. Currently, phosphite injections, along with the use of good agricultural practices, are commonly used as methods of control for PRR.

Given the severity of the disease, however, little is known regarding the biology, population diversity, and the molecular basis for the P. cinnamomi - avocado interaction. Current research of ARP therefore focuses on characterizing the genetic diversity and monitoring pathogen populations using microsatellite markers, and using genomics and genetics tools to characterize effectors genes (RxLR and Crinkler) as well as other genes that are known to contribute to the pathogenicity of the oomycete. The sensitivity and effectiveness of phosphite control and its mode of action towards P. cinnamomi is also being investigated.

 

 * Read more about Phytophthora cinnamomi on our Fact sheet.

 

ARP Team Members

Aaron Maringa: Investigating the adhesion of the oomycete Phytophthora cinnamomi during the early infection of avocado.

Katelyn Baird: Characterising the role of Phytophthora cinnamomi NLP proteins in plant cell infection.

Ncobile Kunene: Development of a transformation system for Phytophthora cinnamomi.

Dr Sylvans Ochola: Establishment of Nicotiana benthamiana pathosystem for functional characterization of Phytophthora cinnamomi effectors and avocado R genes.

Kayla Midgley: Characterising the role of Phytophthora cinnamomi CRN effector proteins in host plant cell death.

Susanna Anbu: -Expression profiling of Nep-like protein (NLP) effector genes during infection in avocado.

Shalya Moodley: Assessing the virulence of dominant Phytophthora cinnamomi genotypes from South African avocado orchards.

 

 

New Publications

Wingfield BD, Berger DK, Coetzee MPA, Duong TA, Martin A, Pham NQ, Van den Berg N, Wilken PM, Arun-Chinnappa KS, Barnes I, Buthelezi S, Dahanayaka BA, Durán A, Engelbrecht J, Feurtey A, Fourie A, Fourie G, Hartley J, Kabwe ENK, Maphosa M, Narh Mensah DL, Nsibo DL, Potgieter L, Poudel B, Stukenbrock EH, Thomas C, Vaghefi N, Welgemoed T, Wingfield MJ. (2022) IMA genome‑F17. 13:19. 10.1186/s43008-022-00104-3
Wienk R, Mostert‑O’Neill M, Abeysekara N, Manosalva P, Freeman B, van den Berg N. (2022) Genetic diversity, population structure and clonal verification in South African avocado cultivars using single nucleotide polymorphism (SNP) markers. Tree Genetics and Genomes 18(41) 10.1007/s11295-022-01573-8 PDF
Joubert M, van den Berg N, Theron J, Swart V. (2022) Transcriptomics Advancement in the Complex Response of Plants to Viroid Infection. International Journal of Molecular Sciences 23(7677) 10.3390/ijms23147677 PDF
Backer R, Engelbrecht J, van den Berg N. (2022) Differing Responses to Phytophthora cinnamomi Infection in Susceptible and Partially Resistant Persea americana (Mill.) Rootstocks: A Case for the Role of Receptor-Like Kinases and Apoplastic Proteases. Frontiers in Plant Science 13 10.3389/fpls.2022.928176 PDF
Hartley J, Engelbrecht J, Van den Berg N. (2022) Detection and prevalence of Rosellinia necatrix in South African avocado orchards. European Journal of Plant Pathology 10.1007/s10658-022-02532-8
Fick A, Swart V, Van den Berg N. (2022) The ups and downs of plant NLR expression during pathogen infection. Frontiers in Plant Science 13:921148. 10.3389/fpls.2022.921148
Midgley KA, van den Berg N, Swart V. (2022) Unraveling plant cell death during Phytophthora Infection. Microorganisms 10(6) 10.3390/microorganisms10061139 PDF
Miyambo TM, Backer R, Engelbrecht J, Joubert F, van der Merwe NA, van den Berg N. (2022) The Identification and Characterization of Endopolygalacturonases in a South African Isolate of Phytophthora cinnamomi. Microorganisms 10(1061) 10.3390/microorganisms10051061 PDF
Fick A, Swart V, Backer R, Bombarely A, Engelbrecht J, van den Berg N. (2022) Partially Resistant Avocado Rootstock Dusa® Shows Prolonged Upregulation of Nucleotide Binding-Leucine Rich Repeat Genes in Response to Phytophthora cinnamomi Infection. Frontiers in Plant Science 13:793644. 10.3389/fpls.2022.793644
Engelbrecht J, Duong TA, Paap T, Hulbert JM, Hanneman J, Van den Berg N. (2022) Population genetic analyses of Phytophthora cinnamomi reveals three lineages and movement between natural vegetation and avocado orchards in South Africa. 10.1094/PHYTO-10-21-0414-R
Magagula P, Taylor N, Swart V, Van den Berg N. (2021) Efficacy of Potential Control Agents Against Rosellinia necatrix and Their Physiological Impact on Avocado. Plant Disease 105(11):PDIS-08. 10.1094/PDIS-08-20-1751-RE
Joubert M, Backer R, Engelbrecht J, Van den Berg N. (2021) Expression of several Phytophthora cinnamomi putative RxLRs provides evidence for virulence roles in avocado. PLoS ONE 16(7):e0254645. 10.1371/journal.pone.0254645 PDF
Engelbrecht J, Duong TA, Prabhu AS, Seedat M, van den Berg N. (2021) Genome of the destructive oomycete Phytophthora cinnamomi provides insights into its pathogenicity and adaptive potential. BMC Genomics 22:302. 10.1186/s12864-021-07552-y
Van den Berg N, Swart V, Backer R, Fick A, Wienk R, Engelbrecht J, Prabhu S. (2021) Advances in understanding defense mechanisms in Persea americana against Phytophthora cinnamomi. Frontiers in Plant Science 12:123. 10.3389/fpls.2021.636339
Mufamadi Z, Fourie G, Willis-Boyum A, van den Berg N. (2020) Husk rot disease: causal agents and disease epidemiology. SAMAC Journal PDF
Malefo M, Mathibela O, Makgopa E, Crampton BG. (2020) Investigating the role of Bowman-Birk serine protease inhibitor in Arabidopsis plants under drought stress. Plant Physiology and Biochemistry 149:286-293. 10.1016/J.PLAPHY.2020.02.007
Welgemoed T, Pierneef R, Sterck L, Van de Peer Y, Swart V, Scheepers KD, Berger DK. (2020) De novo assembly of transcriptomes from a B73 maize line introgressed with a QTL for resistance to gray leaf spot disease reveals a candidate allele of a lectin receptor-like kinase. Frontiers in Plant Science http://bit.ly/2SmKPmT
Van den Berg N, Du Toit M, Morgan SW, Fourie G, De Beer ZW. (2019) First Report of Fusarium euwallaceae on Persea americana in South Africa. Plant Disease 10.1094/PDIS-10-18-1818-PDN
Zumaquero A, Martinez-Ferri E, Matas AJ, Reeksting B, Olivier NA, Pliego-Alfaro F, Barcelo A, van den Berg N, Pliego C. (2019) Rosellinia necatrix infection induces differential gene expression between tolerant and susceptible avocado rootstocks. PLoS ONE 14(2):e0212359. 10.1371/journal.pone.0212359
Backer R, Naidoo S, van den Berg N. (2019) The NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) and Related Family: Mechanistic Insights in Plant Disease Resistance. Frontiers in Plant Science 10:102. 10.3389/fpls.2019.00102
Nsibo DL, Barnes I, Kunene NT, Berger DK. (2019) Influence of farming practices on the population genetics of the maize pathogen Cercospora zeina in South Africa. Fungal Genetics and Biology 125:36-44. 10.1016/j.fgb.2019.01.005
Kuhn DN, Livingstone DS, Richards JH, Manosalva P, van den Berg N, Chambers AH. (2019) Application of genomic tools to avocado (Persea americana) breeding: SNP discovery for genotyping and germplasm characterization. Scientia Horticulturae 246:1-11. 10.1016/j.scienta.2018.10.011
van den Berg N, Mohamed W, Olivier NA, Swart V, Crampton B. (2018) Transcriptome analysis of an incompatible Persea americana-Phytophthora cinnamomi interaction reveals the involvement of SA- and JA-pathways in a successful defense response. PLoS ONE 13(10):e0205705. 10.1371/journal.pone.0205705
van den Berg N, Hartley J, Engelbrecht J, Mufamadi Z, Mavuso Z, van Rooyen Z. (2018) First Report of White Root Rot caused by Rosellinia necatrix on Persea americana in South Africa. Plant Disease 102(9):1850. 10.1094/PDIS-10-17-1637-PDN
van den Berg N, Christie JB, Engelbrecht J, Aveling TAS. (2018) Callose and β-1,3-glucanase inhibit Phytophthora cinnamomi in a resistant avocado rootstock. Plant Pathology 67(5):1150-1160. 10.1111/ppa.12819
Engelbrecht J, Duong TA, van den Berg N. (2017) New microsatellite markers for population studies of Phytophthora cinnamomi, an important global pathogen. Scientific Reports 7:17631. 10.1038/s41598-017-17799-9
Wingfield BD, Berger DK, Steenkamp ET, Lim H-J, Duong TA, Bluhm BH, De Beer ZW, De Vos L, Fourie G, Naidoo K, Olivier NA, Lin Y, Van der Peer Y, Joubert F, Crampton BG, Swart V, Soal N, Tatham C, Van der Nest MA, Van der Merwe NA, Van Wyk S, Wilken PM, Wingfield MJ. (2017) IMA Genome-F 8 Draft genome of Cercospora zeina, Fusarium pininemorale, Hawksworthiomyces lignivorus, Huntiella decipiens and Ophiostoma ips. IMA Fungus 8 (2):385‑396. 10.5598/imafungus.2017.08.02.10 PDF
Prabhu A, Ndlovu B, Engelbrecht J, van den Berg N. (2017) Generation of composite Persea americana (Mill.) (avocado) plants: A proof-of-concept-study. PLoS ONE 12(10): e0185896. 10.1371/journal.pone.0185896
Swart V, Crampton BG, Ridenour JB, Bluhm BH, Olivier NA, Meyer JJM, Berger DK. (2017) Complementation of CTB7 in the maize pathogen Cercospora zeina overcomes the lack of in vitro cercosporin production. Molecular Plant-Microbe Interactions 30(9):710-724. 10.1094/MPMI-03-17-0054-R
Reitmann A, Berger DK, van den Berg N. (2017) Putative pathogenicity genes of Phytophthora cinnamomi identified via RNA-Seq analysis of pre-infection structures. European Journal of Plant Pathology 147(1):211-228. 10.1007/s10658-016-0993-8