Identification, localization and expression analysis of beta-carotene isomerase gene family in sugarcane

Abstract

<p indent=0mm>Strigolactones (SLs), a class of plant hormones, exists widely in plants and involves in the regulation of plant tillering and environmental adaptation. β-carotene isomerase (D27) is a key enzyme for SLs synthesis, but there are few reports about the identification and analysis of <italic>D27</italic> gene family in sugarcane. In this study, five members of <italic>D27</italic> gene family from one of the original parent of modern sugarcane cultivars, <italic>Saccharum spontaneum</italic>, were analyzed. Phylogenetic tree analysis showed that these D27s from <italic>S</italic>.<italic> spontaneum</italic> was clustered into 3 different branches and were highly homologous to sorghum D27s. Conserved domain prediction revealed that D27s contained a typical domain of β-carotene isomerase, Pfam: DUF4033. The results of cis-element analysis showed that<italic> D27s</italic> mainly involved in the regulation of hormone response, plant growth and development, and stress response. Based on the transcriptomic data of the modern cultivated varieties, the expression analysis of the homologous transcripts of <italic>Saccharum spontaneum D27s</italic> showed that <italic>Sspon</italic>.<italic>06G0012830-1A</italic> was regulated at tillering stage and under <italic>Sporisorium scitamineum </italic>infection. Besides, the cDNA sequence of <italic>Sspon</italic>.<italic>06G0012830-1A</italic> was cloned from sugarcane cultivar ROC22 and named as <italic>ScD27</italic>.<italic>1 </italic>(GenBank accession number: MT499895). Bioinformatics analysis indicated that <italic>ScD27</italic>.<italic>1</italic> encoded an unstable protein of 266 amino acids with an isoelectric point of 8.91 and a molecular weight of 30.00 kD, and might be located in the chloroplast, containing chloroplast transit peptides, 4 ubiquitination sites and 18 phosphorylation sites. Its secondary structure mainly included alpha helix and random coils. qRT-PCR analysis demonstrated that <italic>ScD27</italic>.<italic>1</italic> was significantly induced by ABA and H₂O₂ and did not respond to MeJA and SA. Subcellular localization revealed that ScD27.1 might be located in cell membrane and chloroplast and involved in the vesicle sorting or transported by sorting vesicle in plant cells. The results suggested that <italic>ScD27</italic>.<italic>1</italic> may involve in the tillering induced by <italic>S</italic>.<italic> scitamineum </italic>and signaling pathway of ABA and H₂O₂. The present study provides a basic understanding of intracellular transport and tillering in sugarcane and the involvement of <italic>ScD27</italic>.<italic>1 </italic>during sugarcane-<italic>S</italic>.<italic> scitamineum</italic> interaction.