Sugar Transporter Proteins (STPs) in Gramineae Crops: Comparative Analysis, Phylogeny, Evolution, and Expression Profiling

Abstract

Sugar transporter proteins (STPs), such as H+/sugar symporters, play essential roles in plants’ sugar transport, growth, and development, and possess an important potential to enhance plants’ performance of multiple agronomic traits, especially crop yield and stress tolerance. However, the evolutionary dynamics of this important gene family in Gramineae crops are still not well-documented and functional differentiation of rice STP genes remain unclear. To address this gap, we conducted a comparative genomic study of STP genes in seven representative Gramineae crops, which are Brachypodium distachyon (Bd), Hordeum vulgare (Hv), Setaria italica (Si), Sorghum bicolor (Sb), Zea mays (Zm), Oryza rufipogon (Or), and Oryza sativa ssp. japonica (Os). In this case, a total of 177 STP genes were identified and grouped into four clades. Of four clades, the Clade I, Clade III, and Clade IV showed an observable number expansion compared to Clade II. Our results of identified duplication events and divergence time of duplicate gene pairs indicated that tandem, Whole genome duplication (WGD)/segmental duplication events play crucial roles in the STP gene family expansion of some Gramineae crops (expect for Hv) during a long-term evolutionary process. However, expansion mechanisms of the STP gene family among the tested species were different. Further selective force studies revealed that the STP gene family in Gramineae crops was under purifying selective forces and different clades and orthologous groups with different selective forces. Furthermore, expression analysis showed that rice STP genes play important roles not only in flower organs development but also under various abiotic stresses (cold, high-temperature, and submergence stresses), blast infection, and wounding. The current study highlighted the expansion and evolutionary patterns of the STP gene family in Gramineae genomes and provided some important messages for the future functional analysis of Gramineae crop STP genes.

Sugar transporter proteins in Capsicum: identification, characterization, evolution and expression patterns

“…In addition, the number of STP genes in peppers is different from that in other plants. The number of STP genes in C. annuum is higher than that in A. thaliana (14), close to that in S. lycopersicum (18) and S. tuberosum (16), and less than that in Brachypodium distachyon (26), Hordeum vulgare (27), Setaria italica (25), Sorghum bicolor (23), Zea mays (22), O. rufipogon (26), and O. sativa (28) [33]. The difference of STP genes quantity among different species may be related to WGT and fractionation events [34].…”

Micro-Evolution Analysis Reveals Diverged Patterns of Polyol Transporters in Seven Gramineae Crops

“…Sugar is the main product of plant photosynthesis. Sugar (monosaccharides, sucrose, and polyols) plays an important role in the entire life cycle of plants (Deng et al, 2019;Kong et al, 2019a). It can not only provide energy for the growth and the development of plants but also is used for storage and transportation (Kühn and Grof, 2010).…”

“…It can not only provide energy for the growth and the development of plants but also is used for storage and transportation (Kühn and Grof, 2010). In various plant metabolic pathways, sugar can be used as a signal molecule (Wingenter et al, 2010;Kong et al, 2019a). Plant sugar transporters mainly mediate the transportation of sugars, participate in the loading and unloading of various sugars between "source and sink" tissues, and affect the distribution of plant carbohydrates (Kong et al, 2019a;Misra et al, 2019;Patil et al, 2019).…”

“…In various plant metabolic pathways, sugar can be used as a signal molecule (Wingenter et al, 2010;Kong et al, 2019a). Plant sugar transporters mainly mediate the transportation of sugars, participate in the loading and unloading of various sugars between "source and sink" tissues, and affect the distribution of plant carbohydrates (Kong et al, 2019a;Misra et al, 2019;Patil et al, 2019). To date, more and more sugar transporters have been identified and experimentally verified in various plant species, namely, monosaccharide transporters (MSTs), sucrose transporters, and sugars will eventually be exported transporters (Jeena et al, 2019;Kong et al, 2019a;Misra et al, 2019).…”

“…As we all know, polyol transporters (PLTs) belong to a subfamily of the MST superfamily (Deng et al, 2019;Kong et al, 2019a). Previous studies have demonstrated that PLTs can transport polyols and monosaccharides, also known as polyol/monosaccharide transporters (PMTs) (Büttner, 2007;Klepek et al, 2010).…”