AUTHOR=Wu Rongmei , Tomes Sumathi , Karunairetnam Sakuntala , Tustin Stuart D. , Hellens Roger P. , Allan Andrew C. , Macknight Richard C. , Varkonyi-Gasic Erika 

TITLE=SVP-like MADS Box Genes Control Dormancy and Budbreak in Apple

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00477

DOI=10.3389/fpls.2017.00477

ISSN=1664-462X

ABSTRACT=<p>The annual growth cycle of trees is the result of seasonal cues. The onset of winter triggers an endodormant state preventing bud growth and, once a chilling requirement is satisfied, these buds enter an ecodormant state and resume growing. MADS-box genes with similarity to <italic>Arabidopsis SHORT VEGETATIVE PHASE</italic> (<italic>SVP</italic>) [the <italic>SVP</italic>-like and <italic>DORMANCY ASSOCIATED MADS-BOX</italic> (<italic>DAM</italic>) genes] have been implicated in regulating flowering and growth-dormancy cycles in perennials. Here, we identified and characterized three <italic>DAM</italic>-like (<italic>MdDAMs</italic>) and two <italic>SHORT VEGETATIVE PHASE</italic>-like (<italic>MdSVPs</italic>) genes from apple (<italic>Malus × domestica</italic> ‘Royal Gala’). The expression of <italic>MdDAMa</italic> and <italic>MdDAMc</italic> indicated they may play a role in triggering autumn growth cessation. In contrast, the expression of <italic>MdDAMb, MdSVPa and MdSVPb</italic> suggested a role in maintaining bud dormancy. Consistent with this, ectopic expression of <italic>MdDAMb</italic> and <italic>MdSVPa</italic> in ‘Royal Gala’ apple plants resulted in delayed budbreak and architecture change due to constrained lateral shoot outgrowth, but normal flower and fruit development. The association of <italic>MdSVPa</italic> and <italic>MdSVPb</italic> expression with floral bud development in the low fruiting ‘Off’ trees of a biennial bearing cultivar ‘Sciros’ suggested the <italic>SVP</italic> genes might also play a role in floral meristem identity.</p>