#15: Brassica alba Staining

I finally have pictures of slides I stained myself! For a science project, I wanted to qualtiatively compare lignin deposition in root cross-sections of Brassica alba plant roots. I originally planned to use Phloroglucinol-HCL, but I'm not allowed to use high concentrations of HCL (aka no burning something down), so I used the Toluidine Blue stain. 

Toluidine Blue is a metachromatic dye that stains tissue sections for plant histology. It stains lignin, especially in the xylem, green-blue or blue and pectic-rich cell walls, especially in the phloem and parenchyma, reddish-purple.

In order to use this stain, I first diluted the concentrated liquid. I then cut thin cross sections of the plant root right below the soil. I carefully placed these on the slide and then added a few drops of the diluted stain. After 15 seconds, I used the corner of a paper towel to soak up the extra. I flipped each cross-section so that it was upright to look at under the microscope (this took a very, very, very long time, but I eventually got quite good at maneuvering little root pieces).

Also, I could tell the difference between plant roots and shoot cross-sections by the vascular bundle placements. Roots have a central x-shaped vascular cylinder, or stele, that is important for structural strength. Shoots, on the other hand, have bundles in a ring for dictors scattered throughout the ground tissue for monocots, which is important for bending and leaf support.

Part of my project was comparing the effect of silicon seed priming (through monosilicic acid) on lignin deposition, because lignin is a recalcitrant carbon. Here, you can see that the blue in the xylem, which is the lignin, increases by group. Group 1's center is mainly still purple, Group 2 has a little blue, and then Group 3 has much more blue. Qualitatively, this told me that the silicon priming increases lignin deposition (these pictures are representative of each group -- I tested multiple samples).

Here are some more fun pictures. (coming soon, I have to upload them)

Anyway, I'm really happy I finally got to stain some tissues and look at them under the microscope. I still want to look at crystalization (I tried with soy sauce but I think the layer was too thick), and I'll try out some other stains.

Also, here's my final poster if you're curious (but again, I'm updating the poster, so I will have a new one with a better layout and more information coming soon):