How vacuolar sugar transporters evolve and control cellular sugar homeostasis, organ development and crop yield.

Sugar exchange among different subcellular compartments is central for achieving cellular sugar homeostasis and directly affects the yield and quality of many horticultural and field crops. While a portion of photosynthesis-originated sugars is metabolized through glycolysis upon entering the cytosol, the remainder is reversibly channelled to the vacuole, mediated by different families of vacuolar sugar transporter (VST) located on the vacuolar membrane, the tonoplast. Historically, sugar transporters operating on plasma membranes have been studied more than those on tonoplasts.

Apple vacuolar sugar transporters regulated by MdDREB2A enhance drought resistance by promoting accumulation of soluble sugars and activating ABA signaling.

Soluble sugars are not only an important contributor to fruit quality, but also serve as the osmotic regulators in response to abiotic stresses. Early drought stress promotes sugar accumulation, while specific sugar transporters govern the cellular distribution of the sugars. Here, we show that apple plantlets accumulate soluble sugars in leaf tissues under drought stress.

The complex transcriptional regulation of heat stress response in maize.

As one of the most important food and feed crops worldwide, maize suffers much more tremendous damages under heat stress compared to other plants, which seriously inhibits plant growth and reduces productivity. To mitigate the heat-induced damages and adapt to high temperature environment, plants have evolved a series of molecular mechanisms to sense, respond and adapt high temperatures and heat stress. In this review, we summarized recent advances in molecular regulations underlying high temperature sensing, heat stress response and memory in maize, especially focusing on several important pathways and signals in high temperature sensing, and the complex transcriptional regulation of ZmHSFs (Heat Shock Factors) in heat stress response.

Orchids acquire fungal carbon for seed germination: pathways and players.

To germinate in nature, orchid seeds strictly rely on seed germination-promoting orchid mycorrhizal fungi (sgOMFs) for provision of carbon nutrients. The underlying delivery pathway, however, remains elusive. We develop here a plausible model for sugar transport from sgOMFs to orchid embryonic cells to fuel germination.

The MdCBF1/2-MdTST1/2 module regulates sugar accumulation in response to low temperature in apple.

Soluble sugar content is a key component in controlling fruit flavor, and its accumulation in fruit is largely determined by sugar metabolism and transportation. When the diurnal temperature range is greater, the fleshy fruits accumulated more soluble sugars and become more sweeter. However, the molecular mechanism underlying this response remains largely unknown.

How does AT1 increase crop productivity under alkaline stress?

Alkalinity constrains crop production. Recently, Zhang et al. reported a negative regulator, Alkaline Tolerance 1 (AT1), attenuating phosphorylation of plasma membrane intrinsic protein (PIP2) to block efflux of intracellular reactive oxygen species (ROS) under alkaline stress and boosting yield of cereal crops by 20-30%.

Evolution of cytosolic and organellar invertases empowered the colonization and thriving of land plants.

The molecular innovation underpinning efficient carbon and energy metabolism during evolution of land plants remains largely unknown. Invertase-mediated sucrose cleavage into hexoses is central to fuel growth. Why some cytoplasmic invertases (CINs) function in the cytosol, whereas others operate in chloroplasts and mitochondria, is puzzling.

The SnRK2.3-AREB1-TST1/2 cascade activated by cytosolic glucose regulates sugar accumulation across tonoplasts in apple and tomato.

Soluble sugars are the core components of fruit quality, and the degree of sugar accumulation is largely determined by tonoplast-localized sugar transporters. We previously showed that two classes of tonoplast sugar transporters, MdERDL6 and MdTST1/2, coordinately regulate sugar accumulation in vacuoles. However, the mechanism underlying this coordination remains unknown.

Winners take all: competition for carbon resource determines grain fate.

As an evolutionary strategy, plants overproduce ovaries as a safety net for survival, with those losing in the competition for resources being aborted. Grain abortion is, however, highly detrimental agronomically. The molecular basis of selective abortion of grain siblings remains unknown.

Uptake of glucose from the rhizosphere, mediated by apple MdHT1.2, regulates carbohydrate allocation.

Plant roots can absorb sugars from the rhizosphere, which reduces the consumption of carbon derived from photosynthesis. However, the underlying mechanisms that roots use to control sugar absorption from soil are poorly understood. Here, we identified an apple (Malus × domestica Borkh.

coordinates cell elongation via regulating actin filament-dependent vesicle transport.

Plant cell expands via a tip growth or diffuse growth mode. In plants, RabA is the largest group of Rab GTPases that regulate vesicle trafficking. The functions of RabA protein in modulating polarized expansion in tip growth cells have been demonstrated.

Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration.

The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential ( ) of crops is vital to address these challenges. In this review, we explore a component of that has yet to be optimised - that being improvements in the efficiency with which light energy is converted into biomass ( ) via modifications to CO fixed per unit quantum of light (α), efficiency of respiratory ATP production ( ) and efficiency of ATP use ( ).

Maize cytosolic invertase INVAN6 ensures faithful meiotic progression under heat stress.

Faithful meiotic progression ensures the generation of viable gametes. Studies suggested the male meiosis of plants is sensitive to ambient temperature, but the underlying molecular mechanisms remain elusive. Here, we characterized a maize (Zea mays ssp.

Comparative transcriptome and metabolome analyses identified the mode of sucrose degradation as a metabolic marker for early vegetative propagation in bulbs of Lycoris.

Vegetative propagation (VP) is an important practice for production in many horticultural plants. Sugar supply constitutes the basis of VP in bulb flowers, but the underlying molecular basis remains elusive. By performing a combined sequencing technologies coupled with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry approach for metabolic analyses, we compared two Lycoris species with contrasting regeneration rates: high-regeneration Lycoris sprengeri and low-regeneration Lycoris aurea.

Wheat photosystem II heat tolerance: evidence for genotype-by-environment interactions.

High temperature stress inhibits photosynthesis and threatens wheat production. One measure of photosynthetic heat tolerance is T - the critical temperature at which incipient damage to photosystem II (PSII) occurs. This trait could be improved in wheat by exploiting genetic variation and genotype-by-environment interactions (GEI).

Wheat photosystem II heat tolerance responds dynamically to short- and long-term warming.

Wheat photosynthetic heat tolerance can be characterized using minimal chlorophyll fluorescence to quantify the critical temperature (Tcrit) above which incipient damage to the photosynthetic machinery occurs. We investigated intraspecies variation and plasticity of wheat Tcrit under elevated temperature in field and controlled-environment experiments, and assessed whether intraspecies variation mirrored interspecific patterns of global heat tolerance. In the field, wheat Tcrit varied diurnally-declining from noon through to sunrise-and increased with phenological development.

Exploring the Developmental Progression of Endosperm Cavity Formation in Maize Grain and the Underlying Molecular Basis Using X-Ray Tomography and Genome Wide Association Study.

Endosperm cavity (EC) in maize grain reduces yield and causes grain breakage during mechanical harvesting, hence representing a major problem in the maize industry. Despite this, little is known regarding the biological processes governing EC formation. Here, we attempted to address this issue by (i) determining the spatial and temporal progression of EC in a non-invasive manner and (ii) identifying candidate genes that may be linked to the formation of EC by using a genome wide association study (GWAS).

From Raffinose Family Oligosaccharides to Sucrose and Hexoses: Gene Expression Profiles Underlying Host-to-Nematode Carbon Delivery in Roots.

Root-knot nematodes () induce specific feeding sites in cucumber roots where they absorb carbon nutrients from the host, thereby turning the feeding sites into a strong sink for assimilates. Nematode infection may alter host sugar metabolism in the roots of sucrose-transporting species. However, much less is known about the species translocating raffinose family oligosaccharides (RFOs), such as cucumber.

Hexose translocation mediated by SlSWEET5b is required for pollen maturation in Solanum lycopersicum.

Pollen fertility is critical for successful fertilization and, accordingly, for crop yield. While sugar unloading affects the growth and development of all types of sink organs, the molecular nature of sugar import to tomato (Solanum lycopersicum) pollen is poorly understood. However, sugar will eventually be exported transporters (SWEETs) have been proposed to be involved in pollen development.

Sugar conundrum in plant-pathogen interactions: roles of invertase and sugar transporters depend on pathosystems.

It has been increasingly recognized that CWIN (cell wall invertase) and sugar transporters including STP (sugar transport protein) and SWEET (sugar will eventually be exported transporters) play important roles in plant-pathogen interactions. However, the information available in the literature comes from diverse systems and often yields contradictory findings and conclusions. To solve this puzzle, we provide here a comprehensive assessment of the topic.

MdWRKY126 modulates malate accumulation in apple fruit by regulating cytosolic malate dehydrogenase (MdMDH5).

The content of organic acids greatly influences the taste and storage life of fleshy fruit. Our current understanding of the molecular mechanism of organic acid accumulation in apple (Malus domestica) fruit focuses on the aluminum-activated malate transporter 9/Ma1 gene. In this study, we identified a candidate gene, MdWRKY126, for controlling fruit acidity independent of Ma1 using homozygous recessive mutants of Ma1, namely Belle de Boskoop "BSKP" and Aifeng "AF.

A transcriptional landscape underlying sugar import for grain set in maize.

Developing seed depends on sugar supply for its growth and yield formation. Maize (Zea mays L.) produces the largest grains among cereals.