Abstract Detail

Poster Session

Kolp, Matthew [1], Double, Mark [2], Fulbright, Dennis W [3], MacDonald, William [2], Jarosz, Andrew M [1].

Diversity of secondary fungi inhabiting chestnut blight cankers caused by Cryphonectria parasitica in American chestnut (Castanea dentata) populations.

Cryphonectria parasitica, the fungal pathogen that causes chestnut blight on American chestnut (Castanea dentata), has decimated chestnuts throughout its native range.  This necrotrophic fungus enters through wounds in the outer bark and rapidly kills host cells.  Once infected, the cambium and inner bark become necrotic, resulting in a canker that can expand and girdle a stem, killing tissues distal to the canker.  However, not all cankers expand at the same rate, nor do all cankers completely girdle the tree.  We have observed that older cankers on living stems are invaded by secondary fungi.  We hypothesize that a succession of these fungi may play a role in reducing chestnut blight severity.  To test this hypothesis, we sampled cankers from two populations of chestnut in Michigan and one in Wisconsin in 2012.  In 2013, we added two more Michigan chestnut populations to our survey, along with cankers in Maryland with the aim of identifying secondary fungi that invaded cankers.  Isolates were identified initially using cultural characteristics, then confirmed using sequences of the Internal Transcribed Spacer (ITS) region using ITS1 and ITS4 primers.  The species of secondary fungi and their frequencies in cankers was variable spatially across the seven chestnut populations.  Of the isolates recovered from cankers at five separate sites in Michigan in 2013, the frequency of secondary fungi ranged from 40% at Frankfort to 8.7% at Roscommon, with the other three populations, County Line, Leelanau, and Missaukee County, falling within this range at 21.1%, 32% and 22.5% secondary fungi, respectively.  Cankers sampled in Maryland and West Salem, Wisconsin in 2013 yielded isolates of secondary fungi at frequencies of 23.5% and 11%, respectively.  Trichoderma spp. and Penicillium spp. were isolated from cankers at all sites, but the frequency of these genera varied across populations.  Species within both genera have been reported to be competitive soil saprotrophs and have been used as biological control agents.  Other fungi (e.g. Paraconiothyrium, Umbelopsis) were isolated from cankers at most sites at varying frequencies.  Future research will involve re-sampling cankers to document the temporal succession of secondary fungal invaders, as well as identifying Trichoderma spp. and other commonly isolated secondary fungi to species.

1 - Michigan State University, Plant Biology, 612 Wilson Road, #143, East Lansing, MI, 48824, USA
2 - West Virginia University, Plant and Soil Sciences, 1090 Agricultural Sciences Bldg, PO Box 6108, Morgantown, WV, 26506, USA
3 - Michigan State University, Plant Soil and Microbial Sciences, 612 Wilson Road, #158, East Lansing, MI, 48824, USA

Keywords:
chesnut blight
Cryphonectria parasitica
American chestnut
Trichoderma spp.
Penicillium spp.
fungal ecology.

Presentation Type: Offered Paper - Poster
Session: P5
Location: Lincoln Room/Kellogg Hotel and Conference Center
Date: Monday, June 9th, 2014
Time: 8:00 PM
Number: P5004
Abstract ID:177
Candidate for Awards:Graduate Student Poster Presentation Award