The Expanded SWEET Gene Family Following Whole Genome Triplication in Brassica rapa

Abstract

The SWEET family, which includes transcripts of a cohort of plant hexose and sucrose transporters, is considered key to improving crop stress tolerance and yield through its role in manipulating the carbohydrate partitioning process. The functions and regulatory roles of this gene family are variable among different species; thus, to determine these roles, more species-specific information is needed. Brassica rapa displays complicated regulation after a whole-genome triplication (WGT) event, which provides enormous advantages for use in genetic studies, thus it is an ideal model for exploring the functional and regulatory roles of SWEETs from a genetic perspective. In this study, the results of a homology search and phylogenetic relationship analysis revealed the evolutionary footprint of SWEETs among different plant taxa, which showed that plant SWEETs may have originated from Clade II and then expanded from vascular plants. The amino acid sequence characteristics and an analysis of the exon-intron structure of BrSWEETs duplicates clarified that SWEETs retention occurred after a WGT event in B. rapa. An analysis of the transcriptional levels of BrSWEETs in different tissues identified the expression differences among duplicated co-orthologs. In addition, qRT-PCR indicated that the BrSWEETs’ co-orthologs were varied in their stress responses. This study greatly enriches our knowledge of SWEETs in the B. rapa species, which will contribute to future studies on the Brassica-specific regulatory pathways and to creating genetic innovations.

Systematic Genome-Wide Study and Expression Analysis of SWEET Gene Family: Sugar Transporter Family Contributes to Biotic and Abiotic Stimuli in Watermelon

“…In Medicago truncatula [25], cucumber [16], banana [13], Brassica rapa [6], cabbage [17], tomato [19], soybean [23], rubber tree [18], cotton [54], and pear [55], more than half of the SWEET members have six exons and five introns, suggesting that during evolution the molecular features of SWEET genes were highly conserved. Here, the gene structure analysis of ClaSWEET genes indicated that 12 members (about 54.5%) harbored six exons and five introns.…”

“…However, sugars cannot cross the plant bio-membrane system without the assistance of corresponding sugar transporters. These sugar transporters act as bridges that mediate the distribution of sugar between source-sink organs, the exchange of energy, and carbon in multicellular organisms [2,6].…”

Gene duplication and stress genomics in Brassicas: Current understanding and future prospects

“…, TRANSCRIPTION FACTORS OF CONSERVED MOTIF (TIF[F/Y]XG,(TIFY, Saha et al, 2016) LATE EMBRYOGENESIS ABUNDANT(LEA, Liang et al, 2016), SUPEROXIDE DISMUTASE (SOD,Verma et al, 2019), ANNEXIN (ANN,Yadav et al, 2015), SALT OVERLY SENSITIVE(SOS, Cheng et al, 2019), and PHOSPHOLIPASE D (PLD,Lu et al, 2019), were already known to be stress-regulated, whereas new candidates such as HOMOLOGOUS TO E6-AP C TERMINUS (HECT,Alam et al, 2019),LIN-11, ISL-1 AND MEC-3 DOMAIN GENE (LIM, Park et al, 2014), CCCH ZINC FINGER FAMILY(CCCH, Pi et al, 2018), SET DOMAIN GROUP(SDG, Dong et al, 2015), and SUGARS WILL EVENTUALLY BE EXPORTED TRANSPORTER (SWEET,Wei et al, 2019) have also emerged in recent years. Eight of these studies were done on B. rapa, three on B. juncea and two on B. napus (Table…”

Identification of genes associated with abiotic stress tolerance in sweetpotato using weighted gene co-expression network analysis

“…SWEET genes in plants are associated with adaption to adverse environmental conditions including abiotic stress tolerance (Chandran, 2015; Wei et al, 2019; Kafle et al, 2019; Chen et al, 2010) and transcript levels of the Sweet15 gene was reported to be upregulated up to 64-fold higher than the control in Arabidopsis during salt stress (van Zelm et al, 2020; Zhao et al, 2019). Similarly, the expression of MaSWEETs was induced by cold, salt, and osmotic stresses in banana (Miao et al, 2017).…”