ABA-induced serine/threonine protein kinase gene transcribed in rye (Secale cereale L.)

Abstract

We isolated the rye serine/threonine protein kinase (S/T PK) gene, which is responsible for intracellular signal transduction mediated by abscisic acid (ABA) synthesized following drought stress, from the huge genome, i.e., 1Cx = 7917 Mb. cDNA was synthesized from poly(A)+ RNA from ABA-treated leaves and then ligated with pUC118 via EcoRI linker to form a cDNA library. RT-PCR amplified DNA fragment of S/T PK gene was used as a probe to screen the cDNA library. One positive cDNA clone was sequenced to determine the overall 1462 bp of the S/T PK gene, which encodes the S/T PK protein consisting of deduced 363 amino acid residues including 12 catalytic subdomains. Total RNA was extracted from both ABA-treated and ABA-untreated rye Petkus leaves and then run on a 1% agarose gel denatured by formaldehyde, and the RNA was transblotted to a nylon membrane. Next, northern hybridization was conducted on the membrane using the 3′ untranslated 244 bp region as probes. The rye S/T PK gene was transcribed in ABA-treated leaves but not in untreated leaves. We have shown that rye S/T PK, localized on the 2R chromosome, is transcribed via ABA mediation, which indicates the relation to intracellular signal transduction.