Unusual rothschildianum photograph

I would like to share with you an unusual picture:
It is a rothschildianum leaf imprint showing the stomata.
We use guard cell size to know if a plant is 2N or 4N after oryzalin treatment.
Hope you enjoy!

very interesting.
Can you tell us more about what you do???

Great photos! I would also love to hear more.

Unusual aint the half of it! That is incredible! Please tell more (Dont you just love this forum?)

Wow! Very interesting.

Fascinating! So what stomata traits differentiates 2N from 4N?

Interesting.

Impressive. What's a guard-cell please? I'd love to hear all there is to it!

The guard cells are a pair of highly specialized cells which are intended open-close the stomatal pores to allow gas exchange.

The 4N test is quite simple:

Cell size is proportional to ploidy, so the guard-cell size from a 4N plant is higher of the same kind of cell from a 2N plant.

We keep some plants untreated (as a control) of each cross to know the cell size of a "normal" plant, then, we compare the guard-cell size of plants treated and untreated of each cross.

This method is not a "direct" test to certify a plant as 4N since we are not counting the number of cromosomes but it works quite fine.

Eliseo

so what is this one? 2N?4N? None of the above?

I thought someone way back in time claimed orchid stomata where fixed "open" Clearly in your photos that is not true, at least for roth.

SlipperKing said:

I thought someone way back in time claimed orchid Clearly in your photos that is not true, at least for roth.

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As far as I know, the stomata are fixed "open" only during a few days after deflasking... but soon the plant is able to open/close the stomas normally.

I have not made direct observations but that would be really easy to test.

Funny, I was just showing a customer of ours last week how to do this. He has a bunch of Cattleya seedlings, and this is an easy and cheap way to determine which of the seedlings have converted to being tetraploid.

Robert

SlipperKing said:

I thought someone way back in time claimed orchid stomata where fixed "open" Clearly in your photos that is not true, at least for roth.

Click to expand...

Birk certainly wrote that in his revised growers manual

cool!

Can you tell the difference between a 3n and 4n plant using this method?

eaborne said:

Can you tell the difference between a 3n and 4n plant using this method?

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Not with total confidence... the cell size is significatively different in 2N and 4N plants and it is more or less easy to see the difference... but some plants are "dubious"... In any case...cromosome count is much more confident... and expensive

goldenrose said:

so what is this one? 2N?4N? None of the above?

Click to expand...

I think we need a side by side pic of a normal 2N plant next to it to compare?

SlipperKing said:

I thought someone way back in time claimed orchid stomata where fixed "open" Clearly in your photos that is not true, at least for roth.

Click to expand...

I also heard that, but since then I've heard the refinement that most orchid stomata are open during light exposure regardless of humidity conditions.

Since then I've come across a decent article by Zotz that indicated that maybe up to 40 ~+/-% of orchids are CAM or C3/CAM switch hitter plants which open stomata at night (to conserve water). But at this time I haven't come across any documentation that indicates that any slipper species are anything but simple C3 plants, and will open stomata during the day regardless of hydration conditions.

I think the bulk of Cattleya are CAM plants.

I agree with Rick. A side-by-side comparison would be very helpful for those
of us who are basically clueless.