Diurnal Changes in Water Soluble Carbohydrate Components in Leaves and Sucrose Associated TaSUT1 Gene Expression during Grain Development in Wheat

Deciphering High-Temperature-Induced Lignin Biosynthesis in Wheat through Comprehensive Transcriptome Analysis

This study systematically investigated the physiological and molecular responses of the wheat mutant 'XC-MU201' under high-temperature stress through comprehensive transcriptome analysis and physiological measurements. RNA sequencing of 21 samples across seven different treatment groups revealed, through Weighted Gene Co-expression Network Analysis (WGCNA), 13 modules among 9071 genes closely related to high-temperature treatments. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed significant enrichment of lignin biosynthesis-related modules under high-temperature conditions, especially at the H-10DAT, H-20DAT, and H-30DAT time points. Experimental results demonstrated a significant increase in lignin content in high-temperature-treated samples, confirmed by tissue staining methods, indicating wheat's adaptation to heat damage through lignin accumulation. The phenylalanine ammonia-lyase gene (TaPAL33) was significantly upregulated under high-temperature stress, peaking at H-30DAT, suggesting its critical role in cellular defense mechanisms. Overexpression of TaPAL33 in the wheat variety 'Xinchun 11' enhanced lignin synthesis but inhibited growth. Subcellular localization of GFP-labeled TaPAL33 in tobacco cells showed its distribution mainly in the cytoplasm and cell membrane. Transgenic wheat exhibited higher PAL enzyme activity, enhanced antioxidant defense, and reduced oxidative damage under high-temperature stress, outperforming wild-type wheat. These results highlight TaPAL33's key role in improving wheat heat tolerance and provide a genetic foundation for future research and applications.

Optimization of Extraction Parameters and Characterization of Tunisian Date Extract: A Scientific Approach Toward Their Utilization

The response surface methodology (RSM) was used in order to select the extraction conditions of extract from Kentichi date powder; a by-product of the date-processing process. Powder/solvent ratio, extraction temperature, and extraction time all had an impact on sugar yield, and these model factors have quadratic effects influencing sugar yield. Optimal extraction was obtained with 300 g/L powder/solvent ratio, 32.7 °C extraction temperature, and 2.1 h extraction time. Under these conditions, Kentichi date powder's (KDP) sugar yield was 77.1%, which was close to the predicted value of the model (80.50%). The results of Kentichi date powder extract (KDPE) showed that the total sugar content is 160.09 g/L. However, the protein content is 10.31 g/L with a majority of the essential amino acids (essentially glutamic acid (28.39 mg/L) and aspartic acid (9.65 mg/L)). The determination of antioxidant activity of KDPE showed a high activity (DPPH IC₅₀ = 4.8 mg/mL, ABTS IC₅₀ = 3 mg/mL, FRAP = 4.70 μmol AAE/mL and, TAA = 18.04 μmol Fe(II)/mL). The results show also that the freeze-drying technique has a lot of potential for producing powder from KDPE with many desirable properties. The findings indicate that KDPE with a high nutritional value could be used as a component for the formulation of functional foods.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12355-022-01223-2.

The Role of Sugars in Plant Responses to Stress and Their Regulatory Function during Development

Due to their role as energy and carbon sources and their regulatory functions, sugars influence all phases of the plant life cycle, interact with other signaling molecules, including phytohormones, and control plant growth and development [...].

Elevated CO2 Improves the Physiology but Not the Final Yield in Spring Wheat Genotypes Subjected to Heat and Drought Stress During Anthesis

Heat and drought events often occur concurrently as a consequence of climate change and have a severe impact on crop growth and yield. Besides, the accumulative increase in the atmospheric CO2 level is expected to be doubled by the end of this century. It is essential to understand the consequences of climate change combined with the CO2 levels on relevant crops such as wheat. This study evaluated the physiology and metabolite changes and grain yield in heat-sensitive (SF29) and heat-tolerant (LM20) wheat genotypes under individual heat stress or combined with drought applied during anthesis at ambient (aCO2) and elevated CO2 (eCO2) levels. Both genotypes enhanced similarly the WUE under combined stresses at eCO2. However, this increase was due to different stress responses, whereas eCO2 improved the tolerance in heat-sensitive SF29 by enhancing the gas exchange parameters, and the accumulation of compatible solutes included glucose, fructose, β-alanine, and GABA to keep water balance; the heat-tolerant LM20 improved the accumulation of phosphate and sulfate and reduced the lysine metabolism and other metabolites including N-acetylornithine. These changes did not help the plants to improve the final yield under combined stresses at eCO2. Under non-stress conditions, eCO2 improved the yield of both genotypes. However, the response differed among genotypes, most probably as a consequence of the eCO2-induced changes in glucose and fructose at anthesis. Whereas the less-productive genotype LM20 reduced the glucose and fructose and increased the grain dimension as the effect of the eCO2 application, the most productive genotype SF29 increased the two carbohydrate contents and ended with higher weight in the spikes. Altogether, these findings showed that the eCO2 improves the tolerance to combined heat and drought stress but not the yield in spring wheat under stress conditions through different mechanisms. However, under non-stress conditions, it could improve mainly the yield to the less-productive genotypes. Altogether, the results demonstrated that more studies focused on the combination of abiotic stress are needed to understand better the spring wheat responses that help the identification of genotypes more resilient and productive under these conditions for future climate conditions.

Essentiality for rice fertility and alternative splicing of OsSUT1

Sucrose-proton symporters play important roles in carbohydrate transport during plant growth and development. Their physiological functions have only been partly characterized and their regulation mechanism is largely unclear. Here we report that the knockout of a sucrose transporter gene, OsSUT1, by CRISPR-Cas9 mediated gene editing resulted in a slightly dwarf size and complete infertility of the gene's homozygous mutants. Observation of caryopsis development revealed that the endosperm of OsSUT1 mutants failed to cellularize and did not show any sign of seed-filling. Consistently, OsSUT1 was identified to express strongly in developing caryopsis of wild-type rice, particularly in the nucellar epidermis and aleurone which are critical for the uptake of nutrients into the endosperm. These results indicate that OsSUT1 is indispensable during the rice reproductive stage particularly for caryopsis development. Interestingly, OsSUT1 possesses at least 6 alternative splicing transcripts, including the 4 transcripts deposited previously and the other two identified by us. The differences among these transcripts primarily lie in their coding region of the 3' end and 3' UTR region. Real-time PCR showed that 4 of the 6 transcripts had different expressional patterns during rice vegetative and reproductive growth stages. Given the versatility of the gene, addressing its alternative splicing mechanism may expand our understanding of SUT's function substantially.

Source-Sink Dynamics in Field-Grown Durum Wheat Under Contrasting Nitrogen Supplies: Key Role of Non-Foliar Organs During Grain Filling

The integration of high-throughput phenotyping and metabolic approaches is a suitable strategy to study the genotype-by-environment interaction and identify novel traits for crop improvement from canopy to an organ level. Our aims were to study the phenotypic and metabolic traits that are related to grain yield and quality at canopy and organ levels, with a special focus on source-sink coordination under contrasting N supplies. Four modern durum wheat varieties with contrasting grain yield were grown in field conditions under two N fertilization levels in north-eastern Spain. We evaluated canopy vegetation indices taken throughout the growing season, physiological and metabolic traits in different photosynthetic organs (flag leaf blade, sheath, peduncle, awn, glume, and lemma) at anthesis and mid-grain filling stages, and agronomic and grain quality traits at harvest. Low N supply triggered an imbalance of C and N coordination at the whole plant level, leading to a reduction of grain yield and nutrient composition. The activities of key enzymes in C and N metabolism as well as the levels of photoassimilates showed that each organ plays an important role during grain filling, some with a higher photosynthetic capacity, others for nutrient storage for later stages of grain filling, or N assimilation and recycling. Interestingly, the enzyme activities and sucrose content of the ear organs were positively associated with grain yield and quality, suggesting, together with the regression models using isotope signatures, the potential contribution of these organs during grain filling. This study highlights the use of holistic approaches to the identification of novel targets to improve grain yield and quality in C₃ cereals and the key role of non-foliar organs at late-growth stages.