Cloning and Expression Analysis of a Salt-Stress-Induced HD-Zip Transcription Factor <i>HB-12</i> from Sunflower (<i>Helianthus annuus</i> L.)

HB  transcription factor genes play a significant role in plant growth and development, including response to biotic and abiotic stresses. In this study, an HD-Zip transcription factor  HB-12  was cloned from sunflower using SMARTer RACE technology based on Unigene551_All known sequence. The full-length  HB-12 cDNA sequence is 821 bp, including 573 bp open reading frame and encoding 190 amino acids. The predicted protein molecular weight and isoelectric point are 22.55 kD and 5.58, respectively, with a homeobox domain (HD) and a homeobox-associated leucine zipper domain (HALZ). HB-12 belongs to the sunflower HD-Zip I subfamily proteins. The GenBank sequence accession number is KU315052. HB-12 protein does not exist in the transmembrane domain, and its subcellular localization predicted that it might be in the nucleus. Cluster analysis revealed that the sunflower HB-12 is closely related to the HB-12 of potato and tomato crops. Genomic DNA sequence corresponding to the full-length cDNA of  HB-12  was amplified using polymerase chain reaction (PCR). The full length of the coding region is 652 bp, and two exons are separated by one intron. The sequence has been submitted to GenBank (Accession No. KU315053). Real-time PCR analysis showed that  HB-12  expression was induced by salt, abscisic acid (ABA), and polyethylene glycol (PEG) and varied in different organs, such as roots, hypocotyls, and leaves. This study lays a foundation for research in molecular breeding of sunflower.