Molecular identification of the key starch branching enzyme-encoding gene SBE2.3 and its interacting transcription factors in banana fruits

Starch branching enzyme(SBE)has rarely been studied in common starchy banana fruits.For the first time,we report here the molecular characterization of seven SBE(MaSBE)and six SBE(MbSBE)genes in the banana A-and B-genomes,respectively,which could be classified into three distinct subfamilies according to genome-wide identification.Systematic transcriptomic analysis revealed that six MaSBEs and six MbSBEs were expressed in the developing banana fruits of two different genotypes,BaXi Jiao(BX,AAA)and Fen Jiao(FJ,AAB),among which MaSBE2.3 and MbSBE2.3 were highly expressed.Transient silencing of MaSBE2.3 expression in banana fruit discs led to a significant decrease in its transcription,which coincides with significant reductions in total starch and amylopectin contents compared to those of empty vector controls.The suggested functional role of MaSBE2.3 in banana fruit development was corroborated by its transient overexpression in banana fruit discs,which led to significant enhancements in total starch and amylopectin contents.A number of transcription factors,including three auxin response factors(ARF2/12/24)and two MYBs(MYB3/308),that interact with the MaSBE2.3 promoter were identified by yeast one-hybrid library assays.Among these ARFs and MYBs,MaARF2/MaMYB308 and MaARF12/MaARF24/MaMYB3 were demonstrated via a luciferase reporter system to upregulate and downregulate the expression of MaSBE2.3,respectively.

Structure-Function relationship of Australian Acacia seed protein concentrates:Amino acid composition,in vitro protein digestibility and molecular properties

The nutritional,functional,in vitro protein digestibility(PD),structural,and molecular properties of Acacia seed protein concentrates(ASPC)from three Acacia species(Acacia victoriae,A.coriacea and A.cowleana)were investigated and compared with a commercial soy protein isolate(SPI).The essential amino acid profile in ASPC,except for methionine,exceeded the minimum daily requirements for adults recommended by the FAO/WHO.The ASPC PD,particularly from A.victoriae and A.coriacea,was considerably high(64.2-79.3%),but lower than SPI(89.5%).ASPC proteins had higher molecular weights ranging from 50 to 65 kDa(associated with 7S vicilin subunit),better protein solubility and oil absorption capacity than SPI.Emulsifying properties were comparable between ASPC and SPI.Among the Acacia species,the proteins from A.victoriae and A.cowleana exhibited higher protein quality,foaming capacity and solubility compared to A.coriacea.Overall,ASPC from A.victoriae and A.cowleana showed potential as ingredients in food processing.