TY - JOUR
T1 - Infection and development of Phoma medicaginis on moderately resistant and susceptible alfalfa genotypes
AU - Castell-Miller, C. V.
AU - Zeyen, R. J.
AU - Samac, D. A.
PY - 2007/9
Y1 - 2007/9
N2 - In North America, spring black stem and leaf spot, caused by Phoma medicaginis, is one of the most important diseases of alfalfa (Medicago sativa). Symptoms appear initially as small, dark brown to black spots that eventually enlarge and on leaves the spots are associated with chlorosis and defoliation. The infection process of P. medicaginis was previously investigated on susceptible alfalfa genotypes, but little is known about this process with alfalfa plants with differing degrees of resistance. We used light and scanning electron microscopy to follow infection and development of P. medicaginis from pycnidiospore deposition on leaf surfaces through pycnidia formation on selected susceptible and resistant alfalfa genotypes from the USDA core collection. In both old and young leaves, spore germination, penetration, development of mycelium, and pycnidia formation were delayed by approximately 24 h on moderately resistant alfalfa genotypes compared with susceptible genotypes. A similar delay in visible symptom development occurred until about 192 h after inoculation, after which the amount of chlorosis in all genotypes was similar.
AB - In North America, spring black stem and leaf spot, caused by Phoma medicaginis, is one of the most important diseases of alfalfa (Medicago sativa). Symptoms appear initially as small, dark brown to black spots that eventually enlarge and on leaves the spots are associated with chlorosis and defoliation. The infection process of P. medicaginis was previously investigated on susceptible alfalfa genotypes, but little is known about this process with alfalfa plants with differing degrees of resistance. We used light and scanning electron microscopy to follow infection and development of P. medicaginis from pycnidiospore deposition on leaf surfaces through pycnidia formation on selected susceptible and resistant alfalfa genotypes from the USDA core collection. In both old and young leaves, spore germination, penetration, development of mycelium, and pycnidia formation were delayed by approximately 24 h on moderately resistant alfalfa genotypes compared with susceptible genotypes. A similar delay in visible symptom development occurred until about 192 h after inoculation, after which the amount of chlorosis in all genotypes was similar.
KW - Alfalfa
KW - Infection process
KW - Medicago sativa
KW - Phoma medicaginis
KW - Spring black stem and leaf spot
UR - http://www.scopus.com/inward/record.url?scp=39149106076&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=39149106076&partnerID=8YFLogxK
U2 - 10.1080/07060660709507472
DO - 10.1080/07060660709507472
M3 - Article
AN - SCOPUS:39149106076
SN - 0706-0661
VL - 29
SP - 290
EP - 298
JO - Canadian Journal of Plant Pathology
JF - Canadian Journal of Plant Pathology
IS - 3
ER -