Isolation andCharacterization ofa SmallHeatShock Protein GenefromMaize

Amaize (ZeamaysL.)genomic clone (Zmempr 9') wasisolated onthebasis ofitshomology toameiotically expressed LIfium sequence. Radiolabeled probemadefromthemaizegenomic clone detected complementary RNAathigh fidelity. Furthermore, ithybridized toRNAisolated fromstaged (aninterval thatis coincident withmeiotic prophase) maizetassel spikelets. Complimentary RNAwasstrongly (atleast 50-fold) induced during heatshockofmaizesomatic tissue andappeared asasingle sizeclass inNorthern blothybridizations. Sequencing ofthe complete coding region ofZmempr9'confirmed thehomology oftheinferred aminoacidsequence toother small heatshock proteins. Consensus sequences foundintheflanking regions corresponded totheusual signals forinitiation ofRNAtranscription, polyadenylate addition, andtheinduction ofheatshock genes. Thelatter sequences conferred heatshock-specific transient expression inelectroporated protoplasts whencloned into promoterless reporter geneplasmid constructs. Hybrid-selected translations revealed specific translation products ranging from 15to18kilodaltons, providing evidence thatthisgeneisa memberofarelated multigene family. We therefore conclude thatthis maizegenomic DNAclone, recovered through itshomologytoclones formeiotic transcripts inlily, represents a genuine maizesmall heatshockprotein gene.