Endochitinase and ?-1,3-glucanase genes are developmentally regulated during somatic embryogenesis inPicea glauca

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Abstract
Two cDNAs isolated from white spruce [Picea glauca (Moench) Voss] somatic embryos, are predicted to encode a basic class IV chitinase and a β-1,3-glucanase, respectively corresponding to genesPgChi-1 andPgGlu-1. Each represents a multigene family in spruce. Transcripts homologous toPgChi-1 orPgGlu-1 genes were highly abundant in embryogenic tissues and gradually decreased after tissues were placed on abscisic acid-containing maturation medium, with lowest abundance in globular embryos. Transcripts related toPgGlu-1 became highly abundant again in early cotyledonary embryos but decreased thereafter, whereas transcripts related toPgChi-1 were also highly abundant in late cotyledonary embryos and plantlets in vitro; transcripts were either low (PgChi-1) or were not detectable (PgGlu-1) in needles. Wounding, drying and flooding stresses enhancedPgChi-1-andPgGlu-1-related gene expression. Fungal cell wall suspension enhancedPgGlu-1-related transcript accumulation, but reducedPgChi-1-related transcript abundance within 24 h.PgChi-1 andPgGlu-1 and their homologues may have roles in plant defense, and possibly developmental roles during spruce somatic embryo maturation.