Induction of a Thionin, the Jasmonate‐Induced 6 kDa Protein of Barley by 2,6‐Dechloroisonicotinic acid

The systemic acquired resistance (SAR) was studied in barley to find out specific molecular markers for this type of resistance. Such markers may serve as diagnostic tools to indicate the defense‐status of a plant and, additionally, may be used to identify new resistance‐inducing compounds in broad screening experiments. Upon treatment of barley leaves with the resistance‐inducing compound 2,6‐dichloroisomicotinic acid (INA) we found, in addition to a yet unidentified basic protein of 45 kDa (designated BIR‐1) induction of a specific 6kDa polypeptide. Using Northern‐and Western blot analysis this small polypeptide was identified as JIP‐6, a known member of the jasmonate‐induced protein (JIP)‐family of barley that was previously demonstrated to be a leaf thionin (ANDRESEN et al. 1992).