The SWEET gene family in Hevea brasiliensis – its evolution and expression compared with four other plant species

Abstract

SWEET proteins play an indispensable role as a sugar efflux transporter in plant development and stress responses. The SWEET genes have previously been characterized in several plants. Here, we present a comprehensive analysis of this gene family in the rubber tree, Hevea brasiliensis . There are 36 members of the SWEET gene family in this species, making it one of the largest families in plant genomes sequenced so far. Structure and phylogeny analyses of these genes in Hevea and in other species demonstrated broad evolutionary conservation. RNA‐seq analyses revealed that SWEET2, 16, and 17 might represent the main evolutionary direction of SWEET genes in plants. Our results in Hevea suggested the involvement of HbSWEET1a , 2e , 2f , and 3b in phloem loading, HbSWEET10a and 16b in laticifer sugar transport , and HbSWEET9a in nectary‐specific sugar transport. Parallel studies of RNA‐seq analyses extended to three other plant species ( Manihot esculenta , Populus trichocarpa , and Arabidopsis thaliana ) produced findings which implicated MeSWEET10a, 3a, and 15b in M. esculenta storage root development, and the involvement of PtSWEET16b and PtSWEET16d in P. trichocarpa xylem development. RT‐qPCR results further revealed that HbSWEET10a, 16b, and 1a play important roles in phloem sugar transport. The results from this study provide a foundation not only for further investigation into the functionality of the SWEET gene family in Hevea, especially in its sugar transport for latex production, but also for related studies of this gene family in the plant kingdom.

SWEET Gene Family in Medicago truncatula: Genome-Wide Identification, Expression and Substrate Specificity Analysis

“…In previous reports, the SWEET gene family has been characterized in various plant species, such as Arabidopsis [1], rice [30], sweet orange [31], soybean [11], tomato [32], potato [33], sorghum [34], cucumber [5,35], rubber tree ( Hevea brasiliensis ) [36], pineapple ( Ananas comosus ) [37], apple [38], tea plant [39], Chinese cabbage ( Brassica rapa ) [40,41], wheat [13,42], and cabbage ( B. oleracea ) [43]. However, the SWEET gene family in Medicago truncatula is still poorly understood, and the biological functions of MtSWEETs remain largely unknown.…”

Cloning and Functional Assessments of Floral-Expressed SWEET Transporter Genes from Jasminum sambac

“…In general, a typical angiosperm genome contains 15 to 25 SWEET genes, e.g., 17 are encoded in Arabidopsis and 21 in rice. SWEET gene duplication occurs during evolution in numerous plant species, such as Eucalyptus (47 genes) [14], soybean (52) [21], wheat (108) [22], cabbage (30) [23], cultivated cotton (55) [24], and rubber tree (36) [25], contrary to only one single gene encoded by human and Drosophila genomes [16,26]. The four-clade classified SWEET proteins play very important roles in diverse physiological and pathophysiological processes (recent reviews in [14,27,28]).…”

Biological significance of RNA-seq and single-cell genomic research in woody plants

“…LcMCII-1 is positively involved in the regulation of rudimentary leaf senescence in litchi (Wang et al 2017). In the rubber tree (Hevea brasiliensis), the results derived from RNA-seq analyses demonstrated that SWEET2, 16, and 17 might represent the main direction of evolution of the SWEET genes in plants (Sui et al 2017).…”

“…RNA-Seq technology has been used to investigate the cork developmental in hybrid poplar (Populus tremula 9 Populus alba) and 455 candidate genes that are responsible for the biosynthesis of poplar suberin have been identified (Rains et al 2018). RNA-seq analyses have identified the involvement of PtSWEET16b and PtSWEET16d genes in xylem development of P. trichocarpa (Sui et al 2017). RNA-seq analyses have also identified a large number of regulators that are was related to DNA and histone methylation (Yakovlev et al 2016).…”