Distribution patterns of HSP 90 protein in rice

Abstract

Rice seedlings exposed to high and low temperatures, salinity and water stress accumulate 87 and 85 kDa stress-associated-proteins (SAP), collectively referred to as SAP 90. In the present study, we provide evidence that SAP 87 of rice is a member of the eukaryotic stress 90/HSP 90 family. Further, high uninduced levels of rice SAP HSP 90 exist in lemma, palea and culm tissues. Dry seeds of rice, wheat, maize and sorghum also contain high uninduced amounts of this protein. Seed-derived callus tissue show high constitutive levels of this protein as well. When seed and callus tissues were subjected to heat shock, the levels of this protein declined. Tissue print-immunoblot analysis using anti SAP 90 antibodies revealed higher accumulation of SAP/HSP 90 in the vascular bundles/procambial cells and in the outermost cell layers of various leaves as well as in the meristematic cells of the stem apex. In seeds, this protein was most abundant in the seed coat and whole embryo.