Structural and functional analysis of rose class B MADS-box genes ‘MASAKO BP, euB3, and B3’: Paleo-type AP3 homologue ‘MASAKO B3’ association with petal development

Previously, we isolated the class B MADS-box genes ‘MASAKO BP and B3’ homologous to PISTILLATA (PI) and APETALA3 (AP3), respectively, from wild rose (Rosa rugosa Thunb. ex Murray) [K. Kitahara, S. Hirai, H. Fukui, S. Matsumoto, Rose MADS-box genes ‘MASAKO BP and B3’ homologous to class B floral identity genes, Plant Sci. 161 (2001) 549–557]. We isolated another class B MADS-box gene, MASAKO euB3, homologous to AP3 with an euAP3 lineage. To determine the functional difference between the previously isolated paleo-type AP3 homologue MASAKO B3 with a TM6 lineage and MASAKO euB3, we produced Arabidopsis transgenic lines containing MASAKO BP and MASAKO B3, and MASAKO BP and MASAKO euB3. We placed the introduced genes under the control of the cauliflower mosaic virus (CaMV) 35S promoter, and found that the MASAKO BP and MASAKO B3, and MASAKO BP and MASAKO euB3 lines caused a sepals-to-petals- and carpel-to-stamen-like transformation, and sepals-to-petals transformation, respectively, suggesting that MASAKO BP and MASAKO B3 might be a major combination in rose petal and stamen development. This is the first report indicating that the MASAKO B3, paleo-type AP3 homologue gene with a TM6 lineage, is associated with petal as well as stamen identification.