Structure and Expression of Bud Dormancy-Associated MADS-Box Genes (DAM) in European Plum

Abstract

Bud dormancy in temperate perennials ensures the survival of growing meristems under the harsh environmental conditions of autumn and winter, and facilitates an optimal growth and development resumption in the spring. Although the molecular pathways controlling the dormancy process are still unclear, DORMANCY-ASSOCIATED MADS-BOX genes (DAM) have emerged as key regulators of the dormancy cycle in different species. In the present study, we have characterized the orthologs of DAM genes in European plum (Prunus domestica L.). Their expression patterns together with sequence similarities are consistent with a role of PdoDAMs in dormancy maintenance mechanisms in European plum. Furthermore, other genes related to dormancy, flowering, and stress response have been identified in order to obtain a molecular framework of these three different processes taking place within the dormant flower bud in this species. This research provides a set of candidate genes to be genetically modified in future research, in order to better understand dormancy regulation in perennial species.

Identification and Characterization of DAMs Mutations Associated With Early Blooming in Sweet Cherry, and Validation of DNA-Based Markers for Selection

“…As suggested before (Jiménez et al, 2009;Li et al, 2009), posterior subfunctionalization and/or neofunctionalization may have resulted in their actual function. The clustering of the DAM orthologs in two major clades, namely DAM1, -2, and -3; and DAM4, -5, and -6, as previously observed (Prudencio et al, 2018;Balogh et al, 2019;Quesada-Traver et al, 2020;Wang et al, 2020), agrees with previous transcriptomic studies of DAM genes in peach and Japanese apricot, in which two different expression patterns have been observed for the two groups of genes. DAM1, -2, and -3 have a maximum expression during bud set, while DAM4, -5, and -6 show maximum expression when chilling requirement are satisfied (Falavigna et al, 2019).…”

“…The amino acid sequence of PavDAMs recently predicted in 'Royal Lee' and 'Hongdeng' cultivars (Wang et al, 2020) is highly similar to that reported in this work for the 'Regina' genome (99.0 and 99.9%, respectively). The sequence of each PavDAM reported in this work includes the four characteristic domains of MIKC type II MADS-box, as reported earlier in peach, Japanese apricot, or plum (Jiménez et al, 2009;Xu et al, 2014;Quesada-Traver et al, 2020). Furthermore, we observed in this study, that each PavDAM comprises eight exons making the genomic structure of the six genes very similar to that of the DAM genes previously reported in other Prunus species, namely peach, Japanese apricot, European plum (Jiménez et al, 2009;Sasaki et al, 2011;Quesada-Traver et al, 2020).…”

“…The sequence of each PavDAM reported in this work includes the four characteristic domains of MIKC type II MADS-box, as reported earlier in peach, Japanese apricot, or plum (Jiménez et al, 2009;Xu et al, 2014;Quesada-Traver et al, 2020). Furthermore, we observed in this study, that each PavDAM comprises eight exons making the genomic structure of the six genes very similar to that of the DAM genes previously reported in other Prunus species, namely peach, Japanese apricot, European plum (Jiménez et al, 2009;Sasaki et al, 2011;Quesada-Traver et al, 2020). Thus, the six MADS-box (PavDAM) genes identified within the major bloom time QTL in this work, as expected, are solid candidate genes for chilling requirement and bloom time regulation in sweet cherry.…”

“…This chromosome 1 genome region is determinant in the genetic control of chilling requirements and bloom time in sweet cherry, as other QTLs for these traits were also previously reported on the same location in sweet cherry populations from different genetic backgrounds (Dirlewanger et al, 2012 ; Castède et al, 2014 ). Six tandemly arranged MICK c -type MADS-box, denoted DAM genes, have been previously identified in the syntenic region of chromosome 1 in the almond, peach, Japanese apricot, and European plum genomes (Xu et al, 2014 ; Wells et al, 2015 ; Quesada-Traver et al, 2020 ). In sweet cherry, PavDAM genes have been recently cloned and sequenced from flower bud RNA, and their cDNA and predicted amino acid sequences have been reported (Wang et al, 2020 ).…”

“…MADS-box genes play fundamental roles in pathways involved in the transition from vegetative to reproductive phases, growth, floral organ determination, and other processes related to root, leaf, fruit, and gametophyte development (Becker and Theißen, 2003 ; Messenguy and Dubois, 2003 ; Smaczniak et al, 2012 ). The DAM genes reported in sweet cherry, peach, Japanese apricot, and European plum ( Prunus domestica L.) belong to MIKC c Type II of MADS-box genes and are phylogenetically related to Arabidopsis SHORT VEGETATIVE PHASE ( SVP ) and AGAMOUS - LIKE 24 ( AGL24 ) genes, which have been reported as main floral regulators (Jiménez et al, 2009 ; Sasaki et al, 2011 ; Quesada-Traver et al, 2020 ; Wang et al, 2020 ). Analyses of DAM gene expression levels in Prunus species have shown a similar pattern in different years and correlations with photoperiod and temperature changes (Falavigna et al, 2019 ), suggesting that these genes are the main regulators of the dormancy cycle in Prunus species (Yamane, 2014 ).…”