Cold acclimation can induce microtubular cold stability in a manner distinct from abscisic acid

The response of cortical microtubules to low temperature was investigated f or the Chinese winter wheat (Triticum aestivum L.) cultivar Jing Nong 934. Microtubules in the cortex of the root elongation zone disassembled rapidly in response to a cold shock of -7 degreesC and reassembled upon rewarming to 25 degreesC. The microtubules acquired resistance against this cold shoc k in response to cold acclimation in chilling, but non-freezing, temperatur e or after a treatment with abscisic acid (ABA). Cold acclimation and ABA d iffered with respect to the appearance of microtubules: fine, transverse st rands were observed after cold acclimation, whereas ABA produced steeply ob lique microtubule bundles. The findings are discussed in terms of an ABA-in dependent pathway for acquired cold stability of microtubules.