ACCUMULATION OF A NOVEL PR1 PROTEIN IN NICOTIANA-LANGSDORFII LEAVES IN RESPONSE TO VIRUS-INFECTION OR TREATMENT WITH SALICYLIC-ACID

Nicotiana langsdorfii appears to lack the characteristic electrophoret ically mobile acidic pathogenesis related proteins of the PR1 family t ypical to tobacco. However, a cDNA clone of PR1a from tobacco used as a probe in northern blots of tobacco mosaic virus (TMV) infected N. la ngsdorfii RNA detected a band of the expected size of mRNA encoding PR 1 proteins. A novel PR1 protein, of similar molecular weight to the ac idic PR1 proteins of Xanthi-nc but more basic and migrating into nativ e gels run at pH 4.1, was found in whole leaf and interstitial fluid e xtracts from TMV-infected and salicylic acid treated leaves. Unlike th e basic PR1 protein of tobacco (PR1g), the protein was detected by ail antibody to PR1a. (C) 1997 Academic Press Limited.