ScAOC1, an allene oxide cyclase gene,confers defense response to biotic and abiotic stresses in sugarcane

Key message An allene oxide cyclase gene which is involved in defense against biotic and abiotic stresses was cloned and characterized in sugarcane. Allene oxide cyclase (AOC), a key enzyme in jasmonate acid (JA) biosynthesis, affects the stereoisomerism and biological activity of JA molecules, and plays an important role in plant stress resistance. In this study, fourSsAOCalleles (SsAOC1-SsAOC4), which shared similar gene structure and were located on Chr1A, Chr1B, Chr1C, and Chr1D, respectively, were mined from sugarcane wild speciesSaccharum spontaneum, and a homologous geneScAOC1(GenBank Accession Number: MK674849) was cloned from sugarcane hybrid variety Yacheng05-179 inoculated withSporisorium scitamineumfor 48 h. ScAOC1 and SsAOC1-SsAOC4 were alkaline, unstable, hydrophilic, and non-secretory proteins, which possess the same set of conserved motifs and were clustered into one group in the phylogenetic analysis.ScAOC1was expressed in all sugarcane tissues, but with different levels. After infection byS. scitamineum, the transcripts ofScAOC1were increased significantly both in the smut-susceptible (ROC22) and resistant (Yacheng05-179) varieties, but its transcripts were more accumulated and lasted for a longer period in the smut-resistant variety than in the smut-susceptible one.ScAOC1was down-regulated under MeJA and NaCl treatments, but up-regulated under SA, ABA, PEG, and cold stresses. Transiently overexpressingScAOC1gene intoNicotiana benthamianaleaves regulated the responses ofN. benthamianato two pathogensRalstonia solanacearumandFusarium solanivar.coeruleum. Furthermore, prokaryotic expression analysis showed overexpression ofScAOC1inEscherichia coliBL21 could enhance its tolerance to NaCl, mannitol, and cold stimuli. These results indicated thatScAOC1may play an active role in response to biotic and abiotic stresses in sugarcane.