Genome-Wide Identification and Expression Patterns of the SWEET Gene Family in Bletilla striata and its Responses to Low Temperature and Oxidative Stress

Abstract

SWEETs (sugars will eventually be exported transporters), a well-known class of sugar transporters, are involved in plant growth and development, sugar transport, biotic and abiotic stresses, etc. However, to date, there have been few investigations of SWEETs in Orchidaceae. In this study, 23 SWEET genes were identified in Bletilla striata for the first time, with an MtN3/saliva conserved domain, and were divided into four subgroups by phylogenetic tree. The same subfamily members had similar gene structures and motifs. Multiple cis-elements related to sugar and environmental stresses were found in the promoter region. Further, 21 genes were localized on 11 chromosomes and 2 paralogous pairs were found via intraspecific collinearity analysis. Expression profiling results showed that BsSWEETs were tissue-specific. It also revealed that BsSWEET10 and BsSWEET18 were responsive to low temperature and oxidative stresses. In addition, subcellular localization study indicated that BsSWEET15 and BsSWEET16 were localized in the cell membrane. This study provided important clues for the in-depth elucidation of the sugar transport mechanism of BsSWEET genes and their functional roles in response to abiotic stresses.

Comprehensive Functional Analysis of the bZIP Family in Bletilla striata Reveals That BsbZIP13 Could Respond to Multiple Abiotic Stresses

“…Species with more collinear gene pairs (V. planifolia and B. striata) appeared to have relatively closer evolutionary relationships. This was consistent with the collinearity results of other B. striata gene families [42].…”

MdSWEET23, a sucrose transporter from apple (Malus × domestica Borkh.), influences sugar metabolism and enhances cold tolerance in tomato

“…SWEET proteins are mainly localized on the plasma and the tonoplast, while, a few members are also localized on the endoplasmic reticulum and the Golgi membranes ( Chen L. Q. et al., 2015 ; Jeena et al., 2019 ; Breia et al., 2021 ). AtSWEET13 ( Kanno et al., 2016 ) in Arabidopsis , PbSWEET4 ( Ni et al., 2020 ) and PuSWEET15 ( Li et al., 2020 ) in pear, BsSWEET15 and BsSWEET16 ( Lu et al., 2022 ) in Bletilla striata , and SlSWEET14 ( Zhang et al., 2021 ) in tomato, are also localized on the plasma membrane. The localization of sugar transporter ClVST1 shifted from tonoplast in wild-type watermelon to plasma membrane in sweet watermelon, which increased sugar sink potency ( Ren et al., 2020 ).…”

Genome-Wide Identification and Expression Analysis of SWEET Gene Family in Strawberry

“…There are numerous members of the SWEET gene family in higher plants, and studies on the SWEET gene family have been reported: There are 17, 21, 24, 29, 34, 27, 17, 27, 16, 22, 20, 19, 23, 25, and 25 SWEETs identified in Arabidopsis thaliana [10], rice [16], maize [17], tomato [18], Brassica rapa [19], garlic [20], grapes [21], apples [22], litchi [23], watermelon [24], longan [25], jujube [7], Bletilla striata [26], Dendrobium officinale [27], and rose [28], respectively. The members of the SWEET gene family have the specificity of space-time and tissue expression, and there are obvious differences in the types of transported sugar [29].…”