The responses of juvenile leaves of two Eucalyptus species, with contrasting susceptibility to infection by Mycosphaerella leaf disease, were compared. The anatomical changes, accumulation of phenolics, suberin, lignin and anthocyanin and the retention of chlorophyll were studied in leaf lesions of varying developmental stages caused by species of Mycosphaerella. Enhanced resistance of Eucalyptus nitens in southern Australia was attributed to the formation of an effective lignified and suberized necrophylactic periderm, to restrict pathogen spread. Leaves of E. nitens contained isobilateral palisade which resulted in both abaxial and adaxial cell division and the initiation of a strong reinforced cellular zone from an early lesion stage. Eucalyptus globulus formed a slower, distorted necrophylactic periderm through hypertrophic changes to existing mesophyll and limited cell divisions of the single adaxial palisade layer. Deposits of lignin and suberin did not occur until later in lesion development, which were not effective in preventing further disease development. From this study it is hypothesized that tolerance of eucalypts to Mycosphaerella pathogens may be associated with constitutive mesophyll density. © 2007 The Authors.

Item Type:	Refereed Article
Research Division:	Agricultural, Veterinary and Food Sciences
Research Group:	Forestry sciences
Research Field:	Tree improvement (incl. selection and breeding)
Objective Division:	Plant Production and Plant Primary Products
Objective Group:	Forestry
Objective Field:	Hardwood plantations
UTAS Author:	Smith, AH (Dr Anna Smith)
UTAS Author:	Gill, WM (Dr Warwick Gill)
UTAS Author:	Pinkard, E (Dr Elizabeth Pinkard)
UTAS Author:	Mohammed, CL (Professor Caroline Mohammed)
ID Code:	50502
Year Published:	2007
Web of Science® Times Cited:	42
Deposited By:	Agricultural Science
Deposited On:	2007-08-01
Last Modified:	2009-11-05
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