Characterization of the SWEET Gene Family in Longan (Dimocarpus longan) and the Role of DlSWEET1 in Cold Tolerance

Abstract

Sugars will eventually be exported transporters (SWEET), a group of relatively novel sugar transporters, that play important roles in phloem loading, seed and fruit development, pollen development, and stress response in plants. Longan (Dimocarpus longan), a subtropic fruit tree with high economic value, is sensitive to cold. However, whether the SWEET gene family plays a role in conferring cold tolerance upon longan remains unknown. Here, a total of 20 longan SWEET (DlSWEET) genes were identified, and their phylogenetic relationships, gene structures, cis-acting elements, and tissue-specific expression patterns were systematically analyzed. This family is divided into four clades. Gene structures and motifs analyses indicated that the majority of DlSWEETs in each clade shared similar exon–intron organization and conserved motifs. Tissue-specific gene expression suggested diverse possible functions for DlSWEET genes. Cis-elements analysis and quantitative real-time PCR (qRT-PCR) analysis revealed that DlSWEET1 responded to cold stress. Notably, the overexpression of DlSWEET1 improved cold tolerance in transgenic Arabidopsis, suggesting that DlSWEET1 might play a positive role in D. longan’s responses to cold stress. Together, these results contribute to a better understanding of SWEET genes, which could serve as a foundation for the further functional identification of these genes.

Genome-wide identification of bHLH transcription factors and functional analysis in salt gland development of the recretohalophyte sea lavender (Limonium bicolor)

“…At present, there is no report on the specific bHLH gene known to regulate salt gland development in other halophyte species, making it difficult to find homologous and unique genes for salt gland development. Most studies about L. bicolor remain at the developmental level of the epidermal structure of heterologous overexpression plants [ 20 , 46–48 ], and there has been little research into the roles of L. bicolor genes in salt gland generation and salt discharge. Earlier, we confirmed by in situ hybridization that the L. bicolor gene Lb1G04899 ( LbbHLH ) is expressed in salt glands [ 29 ]; what is more, Lb1G04899 participates in salt gland differentiation and responds to salt stress [ 28 ], laying a foundation for further exploration of the effects of bHLH genes in L. bicolor salt tolerance.…”

“…Globally, more than 800 million hectares of cultivated land are currently harmed by high salinity [ 17 ]. It is estimated that soil salinization will impinge on over 20% of global irrigated farmland by 2050 [ 18 , 19 ], seriously threatening food production and food security [ 20 ]. Enough arable land must be maintained to produce sufficient food to feed the worldwide population.…”

Genome-Wide Identification of the Rose SWEET Gene Family and Their Different Expression Profiles in Cold Response between Two Rose Species

“…Previous studies showed that SWEET genes could be induced by low temperatures and participate in cold stress responses in many plants. For example, the overexpression of DlSWEET1 in the tropic fruit plant longan ( Dimocarpus longan ) improved cold tolerance in transgenic Arabidopsis plants [ 58 ]. BoSWEET2b , BoSWEET4a , and BoSWEET15b were significantly upregulated in the cabbage leaves after cold stress [ 13 ].…”

Special Issue “Sugar Transport, Metabolism and Signaling in Plants”

“…In addition to its well-known role as a carbon source and building block, sugar serves as an osmotic agent to confer plants resistance to abiotic stress. Two research papers [ 7 , 8 ] elegantly demonstrated the crucial role of the SWEET gene family in the cold tolerance of plants. In Longan ( Dimocarpus longan ), a subtropic fruit tree with high economic value and sensitivity to cold, ref.…”

“…In Longan ( Dimocarpus longan ), a subtropic fruit tree with high economic value and sensitivity to cold, ref. [ 7 ] carried out a huge study consisting of identifying 20 longan SWEET (referred to as DiSWEET) genes and characterizing their phylogenetic relationships, structures, cis -acting elements and tissue-expression patterns. They found that this transporter family is divided into four clades with conserved motifs and similar exon–intron organization.…”