A Novel Botrytis Species Is Associated with a Newly Emergent Foliar Disease in Cultivated Hemerocallis

Abstract

Foliar tissue samples of cultivated daylilies (Hemerocallis hybrids) showing the symptoms of a newly emergent foliar disease known as ‘spring sickness’ were investigated for associated fungi. The cause(s) of this disease remain obscure. We isolated repeatedly a fungal species which proved to be member of the genus Botrytis, based on immunological tests. DNA sequence analysis of these isolates, using several different phyogenetically informative genes, indicated that they represent a new Botrytis species, most closely related to B. elliptica (lily blight, fire blight) which is a major pathogen of cultivated Lilium. The distinction of the isolates was confirmed by morphological analysis of asexual sporulating cultures. Pathogenicity tests on Hemerocallis tissues in vitro demonstrated that this new species was able to induce lesions and rapid tissue necrosis. Based on this data, we infer that this new species, described here as B. deweyae, is likely to be an important contributor to the development of ‘spring sickness’ symptoms. Pathogenesis may be promoted by developmental and environmental factors that favour assault by this necrotrophic pathogen. The emergence of this disease is suggested to have been triggered by breeding-related changes in cultivated hybrids, particularly the erosion of genetic diversity. Our investigation confirms that emergent plant diseases are important and deserve close monitoring, especially in intensively in-bred plants.

Identification and characterization of Botrytis medusae, a novel cryptic species causing grey mould on wine grapes in Australia

“…Recently, several Botrytis species were shown to exhibit endophytic stages in their lifecycles in a range of flowering plants (Barnes & Shaw, ; Sowley et al ., ; Grant‐Downton et al ., ; Shaw et al ., ). Shaw et al .…”

“…Recently, several Botrytis species were shown to exhibit endophytic stages in their lifecycles in a range of flowering plants (Barnes & Shaw, 2003;Sowley et al, 2009;Grant-Downton et al, 2014;Shaw et al, 2016). Shaw et al (2016) found B. cinerea, B. pseudocinerea, B. mali isolates and an undescribed Botrytis sp.…”

Botrytis species: relentless necrotrophic thugs or endophytes gone rogue?

“…The disease is subtle, showing symptoms such as chlorosis, necrosis and distortion of emerging leaves in the spring. A causative agent had not been formally diagnosed until Grant-Downton et al (2014) identified a fungus isolated repeatedly from infected leaf material as a member of the genus Botrytis. The new species is phylogenetically closest to B. squamosa and B. elliptica (pathogens of onion and lily, respectively) and was named B. deweyae.…”

Analysis of Cryptic, Systemic Botrytis Infections in Symptomless Hosts

“…and other species, including Botrytis deweyae , which cause no visible symptoms on the plant at the initial time of infection, are long-lived, can be isolated from newly grown host tissues, but cause necrotic lesions as the plant moves into a reproductive phase. Cultivated hosts in which this form of infection has been studied include Hemerocallis (Grant-Downton et al, 2014 ), hybrid commercial Primula (Barnes and Shaw, 2002 , 2003 ), and lettuce (Sowley et al, 2010 ). In wild-growing plants, Rajaguru and Shaw ( 2010 ) found widespread infection in leaves of Taraxacum and, to a lesser extent, wild Primula vulgaris .…”