Week 4: June 22 – 28

On Monday and Tuesday, I helped again with another leaf disk assay, though this time I worked not just with Konstantin, but with the VitisGen Powdery Mildew Phenotyping Center.


VitisGen, which I’ve been alluding to in a few of my posts but have not actually addressed, is a collaborative network consisting of grape breeders, plant pathologists, USDA personnel, and faculty/staff from many universities, who research ways to streamline the grape breeding process, primarily by integrating genotypic and phenotypic data to develop molecular markers. Here at the station, I work with members from Cornell University and USDA-ARS. Molecular markers are DNA sequences within the plant’s genome that are associated with a trait. By identifying molecular markers for target traits, plant breeders can screen undesirable individuals more efficiently, saving time, money, and land.

The traits VitisGen focuses their efforts on are those of the most significance to growers and breeders. The 3 most important traits are low temperature responses, fruit quality, and powdery mildew resistance, though other diseases and traits are also investigated as part of a local phenotyping effort. My and Beth’s project is such an effort, seeking out molecular markers for black rot resistance, while Konstantin’s project does the same with Downy Mildew.

On Tuesday night and Wednesday morning we inoculated a second population, the  progeny of ‘Horizon’ x ‘Illinois 547-1’, with black rot. It went quicker this time due to more help from more people: Bruce, Aaron, and Steve (enjoy your retirement!) were generous enough to donate their evenings to Beth and me.

Grape cluster

So, now that both of our populations are inoculated, we just have to sit back and wait for the disease to take hold. In 2 weeks we expect symptoms will begin to be visible, allowing us to rate individuals in the population for their relative resistance to the disease. In the meantime, however, Beth and  I have decided to start a fun little project, isolating strains of fungi from grapevines throughout Geneva. On Wednesday, we went out to the vineyard and collected a bunch of ugly, diseased leaf samples, surface sterilized them with bleach, and then waited a day for the pycnidia to sporulate.

Unfortunately I didn’t take any pictures of this process, since its all pretty small and we lack a fancy picture-taking microscope, but this video shows how the pycnidia release the spores. It kind of looks like stuff coming out of a pimple, if you’re familiar with that particular brand of grossness, and then I knock off the spores with a needle and plate them on a petri dish.

I used a rig like this, stick-n-poke style. Works well.
I used a rig like this, stick-n-poke style. Works well.

Beth and I had a great time during our leaf collection ooh-ing and ahh-ing in the vineyard about how diseased grapes can become when they’re not sprayed. Here are some pictures of our enjoyment, for your enjoyment.

Beth all up in the vine
Beth all up in the vine
A crunchy leaf
A crunchy leaf
Me all up in the vine
Me all up in the vine
Petiolar lesion from black rot
Petiolar lesion from black rot: eventually will girdle the leaf
Severely stunted and black rot-infected vine
Severely stunted and black rot-infected vine

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