Current Activities

I'm helping to compile data from a study looking at a potential new species of Phytophthora, and conducting kochs postulates on several isolates in collaboration with another lab. I'm also pulling together the data from my poster to put into a paper written by a post doc in our lab to try to get that published too. I'm running a mist chamber inoculation concurrently with my field work to compare findings at 2 different temperatures under very moist conditions. I will also be repeating a detache leaf inoculation using P. ramorum as I obtained rather strange results last time.

that's all for now

APS meeting

Here I am at the American Phytopathological Society Meeting in Portland OR earlier this week. I presented this poster on the pathogenic fitness of the clonal lineages of Phytophthora ramorum.

Disease spread

The first photo shows P. syringae spreading aerially, probably by rain splash during winter. The second photo shows P. nicotianae spreading within the plant during late spring/early summer.

research in the news

Here is an article from February of last year on the Salem news website, talking about the importance of research on Phytophthora spp. and other pathogens for the nursery industry in Oregon which recently exceeded $1bn in sales value. Several people I work with are mentioned and my project on the epidemiology of Phytophthora spp on Rhododendron is mentioned.

Field experiment

Finally I am having some success at inoculating my field experiment. Here is a graph showing my initial data. There are significant differences between species and between cultivars and as expected P. syringae (7) is the most aggressive pathogen so far. This photo shows a Rhododendron inoculated with Phytophthora syringae as part of my field experiment. You can see how the infection has spread aerially by rain splash to near by leaves and has dripped down on to the two leaves below the inoculated leaf.

trip to the state capitol

On Friday I went to the capitol building in Salem to testify in favour of house bill 2508 for the abolition of fees for graduate students with a tuition waiver. I went along with other members of the Coalition of Graduate Employees (CGE) the union for the grads on OSU's campus, and the GTFF which is the equivalent at the University of Oregon. The GTFF and CGE are part of the larger union, the American Federation of Teachers (AFT).

the proposed HB 2508 would stop the universities in Oregon from charging fees on top of tuition to graduate students when we have funding which provides a tuition waiver. The current situation sees 17% of my net pay go back to the university each year, last year this amounted to $2840.

Here is a photo of members of CGE and the GTFF in front of the capitol after testifying for over an hour to a concerned committee.
It was a great experience and it seemed that they committee really took on board our message although in these economic times of severe budget cuts it seems unlikely that any dramatic changes will occur in the near future but hopefully this will begin to open up conversations about how we can improve the situation for graduate students in Oregon.

The CGE has also posted remarks about Friday's trip on their blog and you can download an audio recording of the proceedings from Friday's hearing here. The hearing for HB 2508 begins 16min 29sec into the recording and I testify at 38min 15sec and it closes at 1hr 36min 26sec after 12 testimonies in favour of the bill and 1 agains the bill (someone sent to represent the university).

Statistics and Abstract

I've been analysing the data obtained from the experiments last term where I dipped whole plants in inoculum and measured the number of lesions and the area of the lesions on the plant. I have submitted an abstract for a poster to present at one or two meetings this summer.

Phytophthora ramorum - pathogenic fitness of the three clonal lineages

Clare Elliott, Virginia McDonald and Niklaus Grunwald

The Oomycete pathogen Phytophthora ramorum causes sudden oak death on oak and ramorum blight on a wide range of ornamental plants causing severe economic losses to the nursery industry. The US population of P. ramorum consists of three distinct clonal lineages referred to as NA1, NA2, and EU1. The hypothesis of differences in pathogenic fitness among these three lineages was tested through the infection of detached leaves and whole plants in wounded and un-wounded inoculations of Rhododendron. In independent experiments the fitness of isolates within lineages was determined using the fitness components lesion area (LA), sporulation capacity (SC), incubation period (IP_w) and the area under the lesion expansion curve (AULEC) on two cultivars of Rhododendron; the more susceptible cv. R. catawbiense ‘Boursault’ and the moderately resistant cv. ‘Lee’s Dark Purple’. For all wounded detached leaf experiments and for the whole plant work 3 isolates from each clonal lineage were tested, and for the un-wounded detached leaf assay the sample size was increased to 10 isolates per lineage. In the non-wounded whole plant experiments incidence was measured by number of infection points and number of leaves infected and severity was measured by total lesion area and average lesion area per leaf. LA demonstrated significant differences among lineages in two out of three wounded detached leaf experiments; however, SC, IP_w and AULEC showed no consistent significant differences among lineages. There was also no consistent significant cultivar by lineage interaction among the wound inoculated experiments. The non-wounded whole plant dip inoculations showed a trend towards a difference between the NA1 lineage and EU1 and NA2 (0.1>p>0.05) but variability among isolates within lineages means that these slight differences are not statistically significant. In one out of the two experiments on whole plants significant differences between isolates within lineages were observed (p<0.026). style="">

This study indicates that there are minor differences in fitness components among P. ramorum clonal lineages but suggests also that within lineage variability is great. Experiments are ongoing with an increased sample size of 10 isolates per clonal lineage.