Abstract
Rhododendron mucronatum is widely used as a roadside tree in Japan. We have found that the level of a germin-like protein (GLP) markedly increased in R. mucronatum leaves in response to fumigation with NO2. GLPs are ubiquitous extracellular glycoproteins in plants and constitute a highly diverse family that are further divided into 4 subfamilies. Some GLPs possess enzyme activities and the others are stress-inducible. However, the physiological roles remain unelucidated. The GLP identified in R. mucronatum was classified into the subfamily 3.
We cloned two full-length cDNAs for R. mucronatum GLP using degenerate primers based on the N-terminal sequence of the identified protein. The deduced amino acid sequences of cloned GLPs share 77.7% homology, and were grouped into the subfamily 2. Competitive RT-PCR analysis revealed that the GLP mRNA levels increased about 1,000 times upon fumigation with NO2. We are currently analyzing changes in the protein levels by NO2 fumigation.
