DISTRIBUTION PATTERNS OF 104 KDA STRESS-ASSOCIATED PROTEIN IN RICE

A 104 kDa protein (SAP 104) accumulates in rice seedlings in response to several abiotic stress conditions and immunological homologues of r ice SAP IO il have been detected in several monocot and dicot species, as also Neurospora crassa, a fungus. In this report, we show that the amino acid sequence of a tryptic peptide generated from purified SAP 104 bears significant homology with an ATP-binding domain of the HSP 1 00 family proteins of Arabidopsis thaliana and Glycine max. It is furt her shown that differential uninduced and induced (by high-temperature stress) levels of this protein are accumulated in various organs of t he mature rice plant grown under field conditions. Significant uninduc ed levels of this protein were in particular found in developing and m ature rice grains. Seeds/grains of several other plant genera (i.e. Tr iticum aestivum, Zea mays, Brassica juncea) were also found to contain high uninduced levels of SAP 104. Importantly, the levels of uninduce d SAP 104 in rice grains were found to decline during the seed germina tion phase: after two days of germination, this protein was undetectab le in tissues representing pooled sample of seeds and just-emerged see dlings. Tissue print-immunoblotting analysis has indicated that in see ds high levels of this protein are specifically present in the embryo portion.