Blast it all

Of all the wilts, blasts, declines, spots, blights (early and late), smuts, fires, and other types of plant maladies that I’ve gotten to tour this semester as a TA for Plant Pathology, it’s the rusts – as boring and creaky as they sound – that have captured my heart. They’re everything you want in a fungus: edgy, shape-shifting, clever, misbehaved, and mysterious. They’re also some of our most important plant pathogens, culturally and economically. It was the coffee rust Hemileia vastatrix and its devastation of coffee plantations in Ceylon (now called Sri Lanka) in the 1870s that pushed the Brits to acquire a taste for tea. A wheat rust, Puccinia graminis, has evaded our best efforts at breeding resistant varieties of wheat, and creeps ever closer to the Middle East and the Indian subcontinent. Here in the Northeast, Cedar-apple rust (Gymnosporangium juniperis-virginae) sprouts bright orange horns and adorns cedar and juniper trees with unmistakeable alien blobs. Do some googling – you won’t be disappointed.

So what makes a rust a rust? Many of them do indeed create a blistery, red, orange or brown spore-producing growth that coats the host plant. Wheat rust, for example, would be hard to describe with any other word.

Licensed under Public Domain via Common

Wheat stem rust, Puccinia graminis. Photo licensed under Public Domain.

But part of what makes the whole group of “rusts” so sinister is that most have two separate plant hosts. The organism hops from host to alternate host seasonally and under the guise of five different spore types – making them very hard to pin down.

Why five spore types? For the rust fungi, it’s a matter of movement: something that most fungi lack in any obvious sense. So instead of wings or legs or even flagellae to carry these fungi across from host to host, these fungi delegate these tasks to a number of specialized spores. Each spore performs a different type of movement or storage: there’s genetic movement, of course, which happens in two different spore types (one spore to split the genes up, another to recombine them); but also there’s a spore for waiting/overwintering, a spore to hop from primary to alternate host, a different spore to hop back from the alternate host to the primary host, and yet another spore to re-infect the same primary host plant over and over again. It’s this last spore, called a uredia, that often causes the “rust” effect on the host plants.

Pucciniagraminis-teliaweb

Teliospores of Puccinia graminis, viewed at 200x. Photo by the author.

Something that will never get old for me is the ability of microscopes to make a flake of a leaf or a speck of carpet dust into a visual Versailles under magnification. As a TA for the Plant Pathology lab, most of what we do is look at structures under high power – needless to say, I’m one happy clam. So today, as my fellow TA Emma and I were conducting the chaos of 40 students trying to trace out the steps of the life cycles of wheat–barberry rust and white pine–currant rust, I took a moment just to view a particularly lovely slide of teliospores – they’re the red blobs, roughly diamond-shaped, with a lateral cross-wall pictured at left– as they emerged from a telium on a wheat plant.

Maybe you don’t have a microscope, but you can still appreciate these creatures in many ways. An easy challenge to you all: go to any nearby apple tree (crabapple will do), and start looking at leaves with blotchy brown spots on them: turn the leaves upside down, and see what you see. If you find yourself starting suddenly at what looks like a mole sprouting thick tufts of wiry hairs – which I bet you will find if you look – you, my friend, are in the dear company of cedar-apple rust aecia. Who cares what exactly that means: you’re a guest in their world, so take a hand lens, get curious, and enjoy the alien beauty of these fungi.

Doing the Runway Strut: Fall 2014

By Ben Lemmond

Not unlike humans, fall fashion is a major event in the fungi kingdom. The theme this fall is retro-seventies blend of yellow, red, tan, and faded orange. Here are some of the superstars I’ve spotted out and about this week. Also, watch the instructional video below on lending a helping hand (or stick) to a puffball in need.

Graphite Terrarium

By Ben Lemmond

“Be not concerned,” Dr. Cathy Paris advises us, in a soft, lilting voice that could outsparkle Glinda the Good Witch: the twenty-page packet on graminoids that she’s just handed us is “mostly diagrams.” In it we see the somewhat archaically-classified “tribes” of grasses. One can imagine them roving across the land in waves, heads nodding in some ancient agreement (“May our lemmas always be longer than the lowest glume…” “Yes, yes, it is so.”) Every Wednesday, which is Field Botany day in my world, my cohort and I spend a full, 9-5 day with Cathy Paris and Liz Thompson addressing the nuances of the botanical world with direct, unabashedly precise language, squinting along as we’re steered from spikelet to achene to tubercle in an ever-zooming lens of detail.

This is the class that feels most like learning a foreign language. Specifically, there’s an overload of new terminology with no real-life reference points: words you simply have to memorize, because they only attach to one, very specific meaning that exists nowhere else except deep inside the maze of plant anatomy. To actually retain this language requires a little reinforcement, a task that I’m sure we’ve all approached differently. I’ve taken to drawing everything in class because it’s the only way to add dimension to the detail, to take its foreignness and make it familiar. I tried to do that in a different class, our Friday “Field Practicum” class, where we visit sites and decipher the whole story – and it just didn’t work to turn into images. The puzzles of the sites we visit may be bigger in scope, but the way we solve them somehow doesn’t necessitate the translation of a sketch. Perhaps it’s because patching together narratives from imperfect fragments is what social creatures like ourselves are expertly designed to do. At any rate: a few images of class and sketches from my botany notebook, a world I’ve made for myself to remember:

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