Cycloheximide-mediated superinduction of genes involves both native and foreign transcripts in rice (Oryza sativa L.)

Rice seedlings subjected to heat shock show rapid and transient induction of Oshsp17.4-CI, Oshsp17.9A-CI and OsClpB-cyt/hsp100 transcripts. When the seedlings were pre-treated with protein synthesis inhibitor cycloheximide, levels of the above transcripts during heat shock were more elevated than those seen with heat shock alone. Heat stress and cycloheximide co-treatment resulted in higher transcript accumulation in comparison to cycloheximide pre-treatment followed by heat stress. In transgenic plants raised with OsClpB-cyt/hsp100 promoter driving expression of the reporter gus gene, expression of the gus transcript was subjected to similar superinduction event as was seen with native OsClpB-cyt/hsp100 transcripts in untransformed plants. Yeast cells transformed with variably-sized rice ClpB-cyt/hsp100 promoter driving expression of the lacZ reporter transcript showed that specific sequences of the promoter region may be implicated in superinduction.

Research highlights
► Heat shocked rice seedlings show induction of several heat shock gene transcripts.
► Levels of these transcripts go further up with cycloheximide pre- and co-treatment.
► Superinduction is notable at very low concentration of cycloheximide also.
► GUS transcript in genetically transformed rice shows superinduction by cycloheximide.
► Specific sequence of the ClpB-cyt/hsp100 promoter may have a role in superinduction.