Stomatal openings on boxwood leaves yield entry portals for leaf infection by Calonectria pseudonaviculata
- 10 Downloads
The distribution, density, and size of leaf stomata for eight boxwood taxa were investigated using both light and electron microscopy. Stomata, the pores that facilitate gaseous exchange during photosynthesis, were primarily located on the abaxial (lower) epidermis of boxwood leaves with minimal distribution on or along the central vein of the adaxial (upper) surface. Inoculation of boxwood leaves with Calonectria pseudonaviculata at different leaf sites showed that infection occurred only in areas where stomata were present. Scanning and transmission electron microscopic examination of the inoculated leaves also confirmed that the fungal pathogen gains leaf entry through stomatal openings and not by direct penetration of the cuticle. Among the eight boxwood taxa examined, stomatal densities ranged from 116 ± 15 (B. sinica ‘NaNa’) to 326 ± 21 (B. harlandii) stomata per mm2; stomatal size ranged from 500 ± 84 um2 (B. harlandii) to 1052 ± 117 um2 (B. sinica ‘NaNa’); and stomatal area per leaf (density × size) ranged from 88.63 mm2 (‘Justin Brouwers’) to 154.3 mm2 (B. harlandii). No relationship between stomatal density or size and infection rate was observed; relationships between infection rate and stomatal location and stomatal area on the abaxial surface were demonstrated.
KeywordsBoxwood blight Buxus Disease resistance Electron microscopy
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Statement of human and animal rights
This article does not contain any studies with human or animal subjects performed by any of the authors.
- Douglas SM (2012) Boxwood blight-A new disease for Connecticut and the U.S. The Connecticut Agricultural Experiment Station. http://www.ct.gov/caes/lib/caes/documents/publications/disease_alerts/caes_disease_alert_boxwood_blight_01-11-12.pdf. Accessed 16 March 2018
- Gehesquiere B (2014) Cylindrocladium buxicola nom. cons. prop. (syn. Calonectria pseudonaviculata) on Buxus: molecular characterization, epidemiology, host resistance and fungicide control. Dissertation, Ghent University, BelgiumGoogle Scholar
- Hagan AK, Conner K (2013) Boxwood blight – a new disease of boxwood in the nursery and landscape in Alabama. http://alfafarmers.org/uploads/files/Boxwood_Blight_ACES.pdf. Accessed 20 March 2018
- Iriarte F, Paret M, Knox G (2015) IFAS Disease alert: Boxwood blight. http://washington.ifas.ufl.edu/newsletters/2015/06/02/pest-alert-boxwood-blight/. Accessed 16 March 2018
- Williams-Woodward JL (2014) Boxwood blight found in Georgia – disease alert. http://plantpath.caes.uga.edu/extension/extension/documents/GABoxwoodBlightAlertv1.pdf. Accessed 15 March 2018