Histochemical and microspectrophotometric analyses of early wound responses of resistant and susceptible Populus tremuloides inoculated with Entoleuca mammata ( Hypoxylon mammatum)
B. Bucciarelli et al., Histochemical and microspectrophotometric analyses of early wound responses of resistant and susceptible Populus tremuloides inoculated with Entoleuca mammata ( Hypoxylon mammatum), CAN J BOTAN, 77(4), 1999, pp. 548-555
Citations number
31
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE
Stem tissue of resistant and susceptible genotypes of Populus tremuloides M
ichx. wounded or wound-inoculated with Entoleuca mammata (Wahlenberg: Fr.)
J.D. Rogers & Y.-M. Ju was prepared for histochemical and microspectrophoto
metric analysis. Samples were collected over a 96-h period. Parenchyma cell
walls associated with the response zone of infected resistant and suscepti
ble genotypes accumulated phenolic substances having lignin-like properties
. Features of the lignified zone distinguished resistant from susceptible g
enotypes. This zone in the resistant genotype was uniformly lignified, whil
e in the susceptible genotype, it was discontinuous. Wound callus developed
in the infected resistant but not in the susceptible genotype. In the form
er, callus developed internal to the lignified zone, contained phenolic sub
stances, and was visible 48 h after inoculation. In the susceptible, callus
failed to develop. Wounded tissue of both genotypes displayed no distingui
shing response characteristics. Both produced equivalent amounts of callus,
accumulated similar levels of lignin-like substances, and deposited it in
identical locations. It is concluded that resistant P. tremuloides limits i
nfection by E. mammata by two distinct mechanisms: (i) by the development o
f an intact and localized lignified barrier zone and (ii) by the developmen
t of wound callus rich in phenolic substances. The susceptible is ineffecti
ve at developing either of these barriers.