Upload
rufus-j-akinrinlola
View
197
Download
2
Embed Size (px)
Citation preview
RESISTANCE AGAINST PHYTOPHTHORA ROOT AND STEM
(PSRSR) ROT OF SOYBEAN
RUFUS AKINRINLOLA
FOCUS:
PSRSR and impact on soybean The disease cycle of PSRSR Resistance to PSRSR Conclusion
PSRSR AND IMPACT ON SOYBEAN
Phytophthora soybean root and stem rot (PSRSR)
PSRSR is caused by Phytophthora sojae
First discovered in 1948 Indiana
PSRSR is a soilborne disease
Affects all stages of growth
Optimum temperature: 25-30°C
Favored by high humidity and rainfall
Dorrance et al, 2007
PSRSR AND IMPACT ON SOYBEAN
Impacts on soybean PSRSR could attack all soybean parts PSRSR causes seed rot, seedling damping off, root and stem
rot.
Causes stunted growth and reduced standing
Yield loss may be up to 50%
PSRSR could wipe out susceptible varieties
PSRSR destroys upto 300 000acres of soybean in Ohio (1970s)
Worldwide annual loss close to $2 billion (Tyler, 2007) Dorrance et al, 2007
PSRSR AND IMPACT ON SOYBEAN: symptoms
Dorrance et al, 2007
Stem rotSeedling damping off
Root rot
Stunted growth and reduced standing
Tyler, 2007
Spring Under favorable wet high moisture and warm temperature conditions oospores germinate and form mycelia
Mycelia produce sporangia which releases zoospores
DISEASE CYCLE PHYTOPHTHORA SOJAECausing the Phytophthora root and stem rot
(PRSR) of Soybean (Glycine max).
Rufus Akinrinlola PLPT 802
Dead infected plants residues remain in the soil and overwinter for the next growing season
Wind and rain splash spread sporangia and other infective propagules from infected plant to initiate secondary infection in uninfected susceptible host
Secondary inoculum source
Summer
Fall
Oospores overwinter in soil and debris during hatch conditions
Oogonium form by sexual crossing of hypha and produces the survival oospores in the soil
Winter
Zoospores swim towards root exudates of young soybean root tips initiating primary infection
Attachment, encystment and penetration on zoospores into root surface induce root rot and hyphal colonization of the stem induces stem rot
Hyphal tips of Mycelia can also colonize root tips and induce infection
25 - 30°COptimum temperature
Plant description
polycyclic
RESISTANCE TO PSRSR
R-GENE MEDIATED RESISTANCE.
ROOT RESISTANCE.
PARTIAL RESISTANCE.
Dorrance et al, 2007
RESISTANCE TO PSRSR
R-gene mediated resistance.
Involves 14Rps
Expressed as HR
It’s race specific
Active from germinationWu et al, 2010; Dorrance et al, 2007
RESISTANCE TO PSRSR: R-gene mediated resistance
RESISTANCE TO PSRSR
Partial resistance.
Race non-specific/horizontal tolerance
It’s stable and heritable
It’s a multi-genic trait
Limits lesion expansion
Limits severity of root rot
Limits yields losses Dorrance et al, 2007; Wu et al, 2010
RESISTANCE TO PSRSR
Root resistance
Expressed in the root
It is quantitatively inherited
It is an incomplete resistance
It involves several genes
CONCLUSION
Phytophthora soybean root and stem rot is a major soilborne disease of soybean
Annual losses due to the disease worth $2billion
It affects all parts of soybean
The disease is polycyclic in cycle and mostly initiated by zoospores
It’s majorly controlled through resistant varieties
R-gene resistance, partial and root resistance are the major resistance
Commination of both partial and R-gene mediated resistance gives the best protection
QUESTIONS ?
REFERENCES Dorrance, A. E., Robertson, A. E., Cianzo, S., Giesler, L. J., Grau, C. R., Draper, M. A., ... & Anderson, T.
R. (2009). Integrated management strategies for Phytophthora sojae combining host resistance and seed treatments. Plant Disease, 93(9), 875-882.
Dorrance, A. E., Mills, D., Robertson, A. E., Draper, M. A., Giesler, L., & Tenuta, A. (2007). Phytophthora root and stem rot of soybean. The Plant Health Instructor, 1.
Tyler, B. M. (2007). Phytophthora sojae: root rot pathogen of soybean and model oomycete. Molecular plant pathology, 8(1), 1-8.
Wu, X. L., Zhao, J. M., Sun, S., Yang, F., Wang, Y. C., Gai, J. Y., & Xing, H. (2010). A survey of soybean germplasm for resistance to Phytophthora sojae. Euphytica, 176(2), 261-268.