Can’t see the tissues for the tetrapyrroles?

How can you view plant tissues without slipping them a mickey?
Image: UNECE.
Image: UNECE.

Much as I like chlorophyll, sometimes it does get in the way of viewing details. Take for example when you’re trying to discern internal cell structure throughout the thickness of a leaf or – and chosen purely at random, you understand – grass ligule. Well, under those circumstances it is necessary to remove the pesky pigmentation, i.e. to clear the tissues. Many formulations have been used for this in the past, including infamously chloral hydrate (‘an organic compound … once used as sedative and hypnotic drug…’). However, chloral hydrate – which was used in the preparation of a Mickey Finn, ‘a drink laced with a drug (especially chloral hydrate) given to someone without their knowledge in order to incapacitate them’ – and Federally-controlled in the USA, is for some bizarre reason difficult to obtain(!). No matter, Thomas Villani et al. are pleased to introduce the microscopical world to Visikol™, which ‘is as effective as chloral hydrate in providing clarity and resolution of all tissues examined. Tissues become transparent, allowing observation of deeper layers of cells and making it effective in research, botanical and quality control, and for educational applications’. And proof that this is a good find is provided by the revelation that it works with dried and fresh samples of… ‘mouse-ear cress (Arabidopsis thaliana)’ – oh, and ginger (Zingiber officinale), maté (Ilex paraguariensis), lime basil (Ocimum americanum) and oregano (Origanum vulgare…).  Further proof of Visikol’s utility is provided by Adolfina Koroch et al.’s paper “Rapid Staining Method to Detect and Identify Downy Mildew (Peronospora belbahrii) in Basil” in Applications in Plant Sciences. I’m so glad we cleared that up!

[I well remember the little tingle I used to experience when viewing cleared ‘grass leaf tissues’ (OK, I confess, they were ligules!) in the olden days. However, I’m not now sure if it was the unmitigated joy of viewing structures that nobody else had seen before, or the lactic acid I used as a clearing agent just getting into a cut on my fingers… – Ed.]

  • For student work particularly, you’d be surprised what a good job clear corn (maize) syrup (Karo here in the state) does are rendering plant parts and insects clear. Acts as a nice coverslip adhesive (temporary) too. Very economical.