Abstract:

The class B genes，which belong to the MADS-box gene family，play critical roles in regulating the development of petals and stamens in flowering plants. To understand the molecular mechanisms of floral development in garlic（Allium sativum），we cloned and characterized the homologous PISTALLATA/GLOBOSA-like（PI/GLO-like）gene AsPI（GenBank accession number KY272748）from floral buds of garlic cultivar‘Acheng Purple Garlic’. AsPI was 939 bp in cDNA length with an open reading frame of 615 bp corresponding to 204 amino acid residues. The deduced amino acid sequence of AsPI contained a well-conserved MADS domain from amino acids 1–57 and a conserved K box from amino acids 76–140. AsPI had the serine residue and the KHExL sequence within the MADS box and the K box，respectively，a PI motif was present at the C-terminal end，all of which are characteristic of the PI subfamily. The results obtained by sequence alignment and domain analysis indicated that it might belong to PI subfamily of B function genes. Its sequence also formed a subclade with other monocot PI-type genes in phylogenetic analysis. Semi-quantitative and real-time RT-PCR were done to test the expression patterns in different tissues and organs of Allium sativum. The results showed that the expression level in floral buds was the highest，whereas scape followed，little transcripts or no expression was detected in vegetative organs，such as leaf，pseudostem，protective leaf，root. This study developed the positive exploration for preliminary understanding at the molecular level on garlic floral development.

Key words: garlic, Allium sativum, flower development, B-function MADS-box genes, AsPI gene