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Summary Increase in grain yield is always a major objective of wheat genetic improvement. The SQUAMOSA promoter‐binding protein‐like (SPL) genes, coding for a small family of diverse plant‐specific transcription factors, represent important targets for improving grain yield and other major agronomic traits in rice. The function of the SPL genes in wheat remains to be investigated in this respect. In this study, we identified 56 wheat orthologues of rice SPL genes belonging to 19 homoeologous groups. Like in rice, nine orthologous TaSPL genes harbour the microRNA156 recognition elements (MRE) in their last exons except for TaSPL13, which harbour the MRE in its 3′‐untranslated region (3′UTR). We modified the MRE of TaSPL13 using CRISPR‐Cas9 and generated 12 mutations in the three homoeologous genes. As expected, the MRE mutations led to an approximately two‐fold increase in the TaSPL13 mutant transcripts. The phenotypic evaluation showed that the MRE mutations in TaSPL13 resulted in a decrease in flowering time, tiller number, and plant height, and a concomitantly increase in grain size and number. The results show that the TaSPL13 mutants exhibit a combination of different phenotypes observed in Arabidopsis AtSPL3/4/5 mutants and rice OsSPL13/14/16 mutants and hold great potential in improving wheat yield by simultaneously increasing grain size and number and by refining plant architecture. The novel TaSPL13 mutations generated can be utilized in wheat breeding programmes to improve these agronomic traits.

Optimal timing of flowering, a major determinant for crop productivity, is controlled by environmental and endogenous cues. Nutrients are known to modify flowering time; however, our understanding of how nutrients interact with the known pathways, especially at the shoot apical meristem (SAM), is still incomplete. Given the negative side-effects of nitrogen fertilization, it is essential to understand its mode of action for sustainable crop production. We investigated how a moderate restriction by nitrate is integrated into the flowering network at the SAM, to which plants can adapt without stress symptoms. This condition delays flowering by decreasing expression of SUPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) at the SAM. Measurements of nitrate and the responses of nitrate-responsive genes suggest that nitrate functions as a signal at the SAM. The transcription factors NIN-LIKE PROTEIN 7 (NLP7) and NLP6, which act as master regulators of nitrate signaling by binding to nitrate-responsive elements (NREs), are expressed at the SAM and flowering is delayed in single and double mutants. Two upstream regulators of SOC1 (SQUAMOSA PROMOTER BINDING PROTEIN-LIKE3 (SPL3) and SPL5) contain functional NREs in their promoters. Our results point at a tissue-specific, nitrate-mediated flowering time control in Arabidopsis thaliana.

Background Members of the plant-specific SPL gene family (squamosa promoter-binding protein -like) contain the SBP conserved domain and are involved in the regulation of plant growth and development, including the development of plant flowers and plant epidermal hair, the plant stress response, and the synthesis of secondary metabolites. This family has been identified in various plants. However, there is no systematic analysis of the SPL gene family at the genome-wide level of wheat. Results In this study, 56 putative TaSPL genes were identified using the comparative genomics method; we renamed them TaSPL001 - TaSPL056 on their chromosomal distribution. According to the un-rooted neighbor joining phylogenetic tree, gene structure and motif analyses, the 56 TaSPL genes were divided into 8 subgroups. A total of 81 TaSPL gene pairs were designated as arising from duplication events and 64 interacting protein branches were identified as involve in the protein interaction network. The expression patterns of 21 randomly selected TaSPL genes in different tissues (roots, stems, leaves and inflorescence) and under 4 treatments (abscisic acid, gibberellin, drought and salt) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Conclusions The wheat genome contains 56 TaSPL genes and those in same subfamily share similar gene structure and motifs. TaSPL gene expansion occurred through segmental duplication events. Combining the results of transcriptional and qRT-PCR analyses, most of these TaSPL genes were found to regulate inflorescence and spike development. Additionally, we found that 13 TaSPLs were upregulated by abscisic acid, indicating that TaSPL genes play a positive role in the abscisic acid-mediated pathway of the seedling stage. This study provides comprehensive information on the SPL gene family of wheat and lays a solid foundation for elucidating the biological functions of TaSPLs and improvement of wheat yield.

In this study, the DFT/M062X/PCM method was applied to investigate thermodynamic and kinetic aspects of reactions involved in possible mechanisms of antioxidant activity of caffeic acid against HOO● radicals in aqueous medium at different pH values. Kinetic parameters of the reactions involved in HAT (Hydrogen Atom Transfer), RAF (Radical Adduct Formation), and SET (Single Electron Transfer) mechanisms, including reaction energy barriers and bimolecular rate constants, were determined, and identification and characterization of stationary points along the reaction pathways within HAT and RAF mechanisms were performed. Inspection of geometrical parameters and spin densities of the radical products formed within HAT and RAF mechanisms revealed that they are stabilized by hydrogen bonding interactions and the odd electron originated through the reaction with the HOO● radical is spread over the entire molecule, resulting in significant radical stabilization. Thermodynamic and kinetic data collected in this study indicated that increasing pH of the medium boosts the antioxidant activity of caffeic acid by reducing the energy required to generate radicals within the RAF and/or HAT mechanism and, at extremely high pH, where the trianionic form of caffeic acid is a dominant species, by the occurrence of an additional fast, diffusion-limited electron-related channel.

The SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) family of transcription factors is functionally diverse, controlling a number of fundamental aspects of plant growth and development, including vegetative phase change, flowering time, branching, and leaf initiation rate. In natural plant populations, variation in flowering time and shoot architecture have major consequences for fitness. Likewise, in crop species, variation in branching and developmental rate impact biomass and yield. Thus, studies aimed at dissecting how the various functions are partitioned among different SPL genes in diverse plant lineages are key to providing insight into the genetic basis of local adaptation and have already garnered attention by crop breeders. Here we use phylogenetic reconstruction to reveal nine major SPL gene lineages, each of which is described in terms of function and diversification. To assess evidence for ancestral and derived functions within each SPL gene lineage, we use ancestral character state reconstructions. Our analyses suggest an emerging pattern of sub-functionalization, neo-functionalization, and possible convergent evolution following both ancient and recent gene duplication. Based on these analyses we suggest future avenues of research that may prove fruitful for elucidating the importance of SPL gene evolution in plant growth and development.

The aging pathway in flowering regulation is controlled mainly by microRNA156 (miR156). Studies in Arabidopsis thaliana reveal that nine miR156-targeted SQUAMOSA PROMOTER BINDING-LIKE (SPL) genes are involved in the control of flowering. However, the roles of SPLs in flowering remain elusive in grasses. Inflorescence development in switchgrass was characterized using scanning electron microscopy (SEM). Microarray, quantitative reverse transcription polymerase chain reaction (qRT-PCR), chromatin immunoprecipitation (ChIP)-PCR and EMSA were used to identify regulators of phase transition and flowering. Gene function was characterized by downregulation and overexpression of the target genes. Overexpression of SPL7 and SPL8 promotes flowering, whereas downregulation of individual genes moderately delays flowering. Simultaneous downregulation of SPL7/SPL8 results in extremely delayed or nonflowering plants. Furthermore, downregulation of both genes leads to a vegetative-to-reproductive reversion in the inflorescence, a phenomenon that has not been reported in any other grasses. Detailed analyses demonstrate that SPL7 and SPL8 induce phase transition and flowering in grasses by directly upregulating SEPALLATA3 (SEP3) and MADS32. Thus, the SPL7/8 pathway represents a novel regulatory mechanism in grasses that is largely different from that in Arabidopsis. Additionally, genetic modification of SPL7 and SPL8 results in much taller plants with significantly increased biomass yield and sugar release.

Background SPL transcription factors play vital roles in regulating plant growth, development, and abiotic stress responses. Sugar beet ( Beta vulgaris L.), one of the world’s main sugar-producing crops, is a major source of edible and industrial sugars for humans. Although the SPL gene family has been extensively identified in other species, no reports on the SPL gene family in sugar beet are available. Results Eight BvSPL genes were identified at the whole-genome level and were renamed based on their positions on the chromosome. The gene structure, SBP domain sequences, and phylogenetic relationship with Arabidopsis were analyzed for the sugar beet SPL gene family. The eight BvSPL genes were divided into six groups (II, IV, V, VI, VII, and VIII). Of the BvSPL genes, no tandem duplication events were found, but one pair of segmental duplications was present. Multiple cis -regulatory elements related to growth and development were identified in the 2000-bp region upstream of the BvSPL gene start codon (ATG). Using quantitative real-time polymerase chain reaction (qRT-PCR), the expression profiles of the eight BvSPL genes were examined under eight types of abiotic stress and during the maturation stage. BvSPL transcription factors played a vital role in abiotic stress, with BvSPL3 and BvSPL6 being particularly noteworthy. Conclusion Eight sugar beet SPL genes were identified at the whole-genome level. Phylogenetic trees, gene structures, gene duplication events, and expression profiles were investigated. The qRT-PCR analysis indicated that BvSPLs play a substantial role in the growth and development of sugar beet, potentially participating in the regulation of root expansion and sugar accumulation.

Background Among the major transcription factors, SPL plays a crucial role in plant growth, development, and stress response. Foxtail millet ( Setaria italica ), as a C4 crop, is rich in nutrients and is beneficial to human health. However, research on the foxtail millet SPL (SQUAMOSA PROMOTER BINDING-LIKE) gene family is limited.  Results In this study, a total of 18 SPL genes were identified for the comprehensive analysis of the whole genome of foxtail millet. These SiSPL genes were divided into seven subfamilies (I, II, III, V, VI, VII, and VIII) according to the classification of the Arabidopsis thaliana SPL gene family. Structural analysis of the SiSPL genes showed that the number of introns in subfamilies I and II were much larger than others, and the promoter regions of SiSPL genes were rich in different cis-acting elements. Among the 18 SiSPL genes, nine genes had putative binding sites with foxtail millet miR156. No tandem duplication events were found between the SiSPL genes, but four pairs of segmental duplications were detected. The SiSPL genes expression were detected in different tissues, which was generally highly expressed in seeds development process, especially SiSPL6 and SiSPL16, which deserve further study. The results of the expression levels of SiSPL genes under eight types of abiotic stresses showed that many stress responsive genes, especially SiSPL9 , SiSPL10 , and SiSPL16 , were highly expressed under multiple stresses, which deserves further attention. Conclusions In this research, 18 SPL genes were identified in foxtail millet, and their phylogenetic relationships, gene structural features, duplication events, gene expression and potential roles in foxtail millet development were studied. The findings provide a new perspective for the mining of the excellent SiSPL gene and the molecular breeding of foxtail millet.

Background Squamous promoter binding protein-like (SPL) proteins are a class of transcription factors that play essential roles in plant growth and development, signal transduction, and responses to biotic and abiotic stresses. The rapid development of whole genome sequencing has enabled the identification and characterization of SPL gene families in many plant species, but to date this has not been performed in quinoa ( Chenopodium quinoa ). Results This study identified 23 SPL genes in quinoa, which were unevenly distributed on 18 quinoa chromosomes. Quinoa SPL genes were then classified into eight subfamilies based on homology to Arabidopsis thaliana SPL genes. We selected three dicotyledonous and monocotyledonous representative species, each associated with C. quinoa , for comparative sympatric mapping to better understand the evolution of the developmental mechanisms of the CqSPL family. Furthermore, we also used 15 representative genes from eight subfamilies to characterize CqSPL s gene expression in different tissues and at different fruit developmental stages under six different abiotic stress conditions. Conclusions This study, the first to identify and characterize SPL genes in quinoa, reported that CqSPL genes, especially CqSPL1 , play a critical role in quinoa development and in its response to various abiotic stresses.

In this study, a combined hydrogen, heat and power (CHHP)-based microgrid (CHHP-MG) is investigated to provide thermal, hydrogen, and electricity loads in order to improve economic and environmental constraints. To increase efficiency of the proposed MG, two different structures are suggested and analyzed. Also, in order to increase economic profits and reduce pollution, management programs are applied to both generation and consumption sectors and their results are reviewed. Real time -based demand response (RTP-DR) is employed to the management side to improve consumptions pattern. The combination of sun flower optimization (SFO) algorithm and VIKOR technique is used to solve and select optimum solution among all obtained solutions. The results indicate the positive impact of the implemented management programs. However, by applying the program to the consumption side, the production side, and both sides, the microgrid’s total pollution are reduced 23%, 41% and 43%This is while the microgrid operator’s profit increases by 32.76%, 45.8%and 65%, respectively.