title: Lineage-Specific Evolutionary Histories and Regulation of Major Starch Metabolism Genes during Banana Ripening.
abstract: Starch is the most widespread and abundant storage carbohydrate in plants. It is also a major feature of cultivated bananas as it accumulates to large amounts during banana fruit development before almost complete conversion to soluble sugars during ripening. Little is known about the structure of major gene families involved in banana starch metabolism and their evolution compared to other species. To identify genes involved in banana starch metabolism and investigate their evolutionary history, we analyzed six gene families playing a crucial role in plant starch biosynthesis and degradation: the ADP-glucose pyrophosphorylases (AGPases), starch synthases (SS), starch branching enzymes (SBE), debranching enzymes (DBE), α-amylases (AMY) and β-amylases (BAM). Using comparative genomics and phylogenetic approaches, these genes were classified into families and sub-families and orthology relationships with functional genes in Eudicots and in grasses were identified. In addition to known ancestral duplications shaping starch metabolism gene families, independent evolution in banana and grasses also occurred through lineage-specific whole genome duplications for specific sub-families ofAGPase, SS, SBE, andBAMgenes; and through gene-scale duplications forAMYgenes. In particular, banana lineage duplications yielded a set ofAGPase, SBEandBAMgenes that were highly or specifically expressed in banana fruits. Gene expression analysis highlighted a complex transcriptional reprogramming of starch metabolism genes during ripening of banana fruits. A differential regulation of expression between banana gene duplicates was identified forSBEandBAMgenes, suggesting that part of starch metabolism regulation in the fruit evolved in the banana lineage.
authors.affiliation: CIRAD, UMR AGAPMontpellier, France; CIRAD, UMR PVBMTSaint-Pierre, France.
authors.forename: Cyril
authors.initials: C
authors.lastname: Jourda
authors.affiliation: CIRAD, UMR AGAP Montpellier, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Cardi
authors.affiliation: CIRAD, UMR QUALISUDMontpellier, France; CIRAD, UMR QUALISUDJakarta, Indonesia.
authors.forename: Olivier
authors.initials: O
authors.lastname: Gibert
authors.affiliation: CIRAD, UMR QUALISUD Montpellier, France.
authors.forename: Andrès
authors.initials: A
authors.lastname: Giraldo Toro
authors.affiliation: CIRAD, UMR QUALISUD Montpellier, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Ricci
authors.affiliation: CIRAD, UMR QUALISUDMontpellier, France; CIRAD, UMR QUALISUDCapesterre-Belle-Eau, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Mbéguié-A-Mbéguié
authors.affiliation: CIRAD, UMR AGAP Montpellier, France.
authors.forename: Nabila
authors.initials: N
authors.lastname: Yahiaoui
keywords: Musa acuminata; amylases; evolution; fruit; gene duplication; starch