Finally here is a method that worked for me. The key to the success of this protocol rests, I think, with the initial, high molarity potassium acetate ppt. The RNA is rescued from the bad things that ppt out. In our hands we found elimination of steps or short cuts after the high molarity ppt still gave RNA, but less pure. Needle tissue is composed of a large amount of non-living cell wall tissue and a low amount of protoplasm per gram fresh weight.
Yields are much lower than with seedling tissue.
I have another protocol for the latter. DEP-treat water, autoclave and use for making up solutions. Wear plastic gloves and use flamed forcepts to touch lips of tubes or pick up miracloth, etc. When cool add 5 mM thiourea 0.038 g 1 mM aurintricarboxylic acid 0.0422g 10 mM dithiotreitol 0.1542g 2. Adjust volume if necessary.