Catálogo de publicaciones - revistas

<jats:title>SUMMARY</jats:title><jats:p>Precise regulation of flowering time is critical for cereal crops to synchronize reproductive development with optimum environmental conditions, thereby maximizing grain yield. The plant‐specific gene <jats:italic>GIGANTEA</jats:italic> (<jats:italic>GI</jats:italic>) plays an important role in the control of flowering time, with additional functions on the circadian clock and plant stress responses. In this study, we show that <jats:italic>GI</jats:italic> loss‐of‐function mutants in a photoperiod‐sensitive tetraploid wheat background exhibit significant delays in heading time under both long‐day (LD) and short‐day photoperiods, with stronger effects under LD. However, this interaction between GI and photoperiod is no longer observed in isogenic lines carrying either a photoperiod‐insensitive allele in the <jats:italic>PHOTOPERIOD1</jats:italic> (<jats:italic>PPD1</jats:italic>) gene or a loss‐of‐function allele in <jats:italic>EARLY FLOWERING 3</jats:italic> (<jats:italic>ELF3</jats:italic>), a known repressor of <jats:italic>PPD1</jats:italic>. These results suggest that the normal circadian regulation of <jats:italic>PPD1</jats:italic> is required for the differential effect of <jats:italic>GI</jats:italic> on heading time in different photoperiods. Using crosses between mutant or transgenic plants of <jats:italic>GI</jats:italic> and those of critical genes in the flowering regulation pathway, we show that <jats:italic>GI</jats:italic> accelerates wheat heading time by promoting <jats:italic>FLOWERING LOCUS T1</jats:italic> (<jats:italic>FT1</jats:italic>) expression via interactions with <jats:italic>ELF3</jats:italic>, <jats:italic>VERNALIZATION 2</jats:italic> (<jats:italic>VRN2</jats:italic>), <jats:italic>CONSTANS</jats:italic> (<jats:italic>CO</jats:italic>), and the age‐dependent microRNA172‐<jats:italic>APETALA2</jats:italic> (<jats:italic>AP2</jats:italic>) pathway, at both transcriptional and protein levels. Our study reveals conserved <jats:italic>GI</jats:italic> mechanisms between wheat and Arabidopsis but also identifies specific interactions of GI with the distinctive photoperiod and vernalization pathways of the temperate grasses. These results provide valuable knowledge for modulating wheat heading time and engineering new varieties better adapted to a changing environment.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Epigenetic regulation of gene expression plays a crucial role in plant development and environmental adaptation. The H3K4me3 and H3K27me3 have not only been discovered in the regulation of gene expression in multiple biological processes but also in responses to abiotic stresses in plants. However, evidence for the presence of both H3K4me3 and H3K27me3 on the same nucleosome is sporadic. Cold‐induced deposition of bivalent H3K4me3‐H3K27me3 modifications and nucleosome depletion over a considerable number of active genes is documented in potato tubers and provides clues on an additional role of the bivalent modifications. Limited by the available information of genes encoding PcG/TrxG proteins as well as their corresponding mutants in potatoes, the molecular mechanism underlying the cold‐induced deposition of the bivalent mark remains elusive. In this study, we found a similar deposition of the bivalent H3K4me3‐H3K27me3 mark over 2129 active genes in cold‐treated <jats:italic>Arabidopsis</jats:italic> Col‐0 seedlings. The expression levels of the bivalent mark‐associated genes tend to be independent of bivalent modification levels. However, these genes were associated with greater chromatin accessibility, presumably to provide a distinct chromatin environment for gene expression. In mutants <jats:italic>clf</jats:italic>28 and <jats:italic>lhp</jats:italic>1, failure to deposit H3K27me3 in active genes upon cold treatment implies that the CLF is potentially involved in cold‐induced deposition of H3K27me3, with assistance from LHP1. Failure to deposit H3K4me3 during cold treatment in <jats:italic>atx</jats:italic>1‐2 suggests a regulatory role of ATX1 in the deposition of H3K4me3. In addition, we observed a cold‐induced global reduction in nucleosome occupancy, which is potentially mediated by LHP1 in an H3K27me3‐dependent manner.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Upland cotton, the mainly cultivated cotton species in the world, provides over 90% of natural raw materials (fibers) for the textile industry. The development of cotton fibers that are unicellular and highly elongated trichomes on seeds is a delicate and complex process. However, the regulatory mechanism of fiber development is still largely unclear in detail. In this study, we report that a homeodomain‐leucine zipper (HD‐ZIP) IV transcription factor, GhHOX4, plays an important role in fiber elongation. Overexpression of <jats:italic>GhHOX4</jats:italic> in cotton resulted in longer fibers, while <jats:italic>GhHOX4</jats:italic>‐silenced transgenic cotton displayed a “shorter fiber” phenotype compared with wild type. GhHOX4 directly activates two target genes, <jats:italic>GhEXLB1D</jats:italic> and <jats:italic>GhXTH2D</jats:italic>, for promoting fiber elongation. On the other hand, phosphatidic acid (PA), which is associated with cell signaling and metabolism, interacts with GhHOX4 to hinder fiber elongation. The basic amino acids KR‐R‐R in START domain of GhHOX4 protein are essential for its binding to PA that could alter the nuclear localization of GhHOX4 protein, thereby suppressing the transcriptional regulation of GhHOX4 to downstream genes in the transition from fiber elongation to secondary cell wall (SCW) thickening during fiber development. Thus, our data revealed that GhHOX4 positively regulates fiber elongation, while PA may function in the phase transition from fiber elongation to SCW formation by negatively modulating GhHOX4 in cotton.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>The root system is important for the absorption of water and nutrients by plants. Cultivating and selecting a root system architecture (RSA) with good adaptability and ultrahigh productivity have become the primary goals of agricultural improvement. Exploring the correlation between the RSA and crop yield is important for cultivating crop varieties with high‐stress resistance and productivity. In this study, 277 cucumber varieties were collected for root system image analysis and yield using germination plates and greenhouse cultivation. Deep learning tools were used to train ResNet50 and U‐Net models for image classification and segmentation of seedlings and to perform quality inspection and productivity prediction of cucumber seedling root system images. The results showed that U‐Net can automatically extract cucumber root systems with high quality (F1_score ≥ 0.95), and the trained ResNet50 can predict cucumber yield grade through seedling root system image, with the highest F1_score reaching 0.86 using 10‐day‐old seedlings. The root angle had the strongest correlation with yield, and the shallow‐ and steep‐angle frequencies had significant positive and negative correlations with yield, respectively. RSA and nutrient absorption jointly affected the production capacity of cucumber plants. The germination plate planting method and automated root system segmentation model used in this study are convenient for high‐throughput phenotypic (HTP) research on root systems. Moreover, using seedling root system images to predict yield grade provides a new method for rapidly breeding high‐yield RSA in crops such as cucumbers.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>The natural variation of plant‐specialized metabolites represents the evolutionary adaptation of plants to their environments. However, the molecular mechanisms that account for the diversification of the metabolic pathways have not been fully clarified. Rice plants resist attacks from pathogens by accumulating diterpenoid phytoalexins. It has been confirmed that the composition of rice phytoalexins exhibits numerous natural variations. Major rice phytoalexins (momilactones and phytocassanes) are accumulated in most cultivars, although oryzalactone is a cultivar‐specific compound. Here, we attempted to reveal the evolutionary trajectory of the diversification of phytoalexins by analyzing the oryzalactone biosynthetic gene in <jats:italic>Oryza</jats:italic> species. The candidate gene, <jats:italic>KSLX‐OL</jats:italic>, which accounts for oryzalactone biosynthesis, was found around the single‐nucleotide polymorphisms specific to the oryzalactone‐accumulating cultivars in the long arm of chromosome 11. The metabolite analyses in <jats:italic>Nicotiana benthamiana</jats:italic> and rice plants overexpressing <jats:italic>KSLX‐OL</jats:italic> indicated that <jats:italic>KSLX‐OL</jats:italic> is responsible for the oryzalactone biosynthesis. <jats:italic>KSLX‐OL</jats:italic> is an allele of <jats:italic>KSL8</jats:italic> that is involved in the biosynthesis of another diterpenoid phytoalexin, oryzalexin S and is specifically distributed in the AA genome species. <jats:italic>KSLX‐NOL</jats:italic> and <jats:italic>KSLX‐bar</jats:italic>, which encode similar enzymes but are not involved in oryzalactone biosynthesis, were also found in AA genome species. The phylogenetic analyses of <jats:italic>KSLX</jats:italic>s, <jats:italic>KSL8</jats:italic>s, and related pseudogenes (<jats:italic>KSL9</jats:italic>s) indicated that <jats:italic>KSLX‐OL</jats:italic> was generated from a common ancestor with <jats:italic>KSL8</jats:italic> and <jats:italic>KSL9</jats:italic> via gene duplication, functional differentiation, and gene fusion. The wide distributions of <jats:italic>KSLX‐OL</jats:italic> and <jats:italic>KSL8</jats:italic> in AA genome species demonstrate their long‐term coexistence beyond species differentiation, suggesting a balancing selection between the genes.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Trehalose‐6‐phosphate (T6P) functions as a vital proxy for assessing carbohydrate status in plants. While class II T6P synthases (TPS) do not exhibit TPS activity, they are believed to play pivotal regulatory roles in trehalose metabolism. However, their precise functions in carbon metabolism and crop yield have remained largely unknown. Here, <jats:italic>BnaC02.TPS8</jats:italic>, a class II TPS gene, is shown to be specifically expressed in mature leaves and the developing pod walls of <jats:italic>Brassica napus</jats:italic>. Overexpression of <jats:italic>BnaC02.TPS8</jats:italic> increased photosynthesis and the accumulation of sugars, starch, and biomass compared to wild type. Metabolomic analysis of <jats:italic>BnaC02.TPS8</jats:italic> overexpressing lines and CRISPR/Cas9 mutants indicated that <jats:italic>BnaC02.TPS8</jats:italic> enhanced the partitioning of photoassimilate into starch and sucrose, as opposed to glycolytic intermediates and organic acids, which might be associated with TPS activity. Furthermore, the overexpression of <jats:italic>BnaC02.TPS8</jats:italic> not only increased seed yield but also enhanced seed oil accumulation and improved the oil fatty acid composition in <jats:italic>B. napus</jats:italic> under both high nitrogen (N) and low N conditions in the field. These results highlight the role of class II TPS in impacting photosynthesis and seed yield of <jats:italic>B. napus</jats:italic>, and <jats:italic>BnaC02.TPS8</jats:italic> emerges as a promising target for improving <jats:italic>B. napus</jats:italic> seed yield.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Carotenoids perform a broad range of important functions in humans; therefore, carotenoid biofortification of maize (<jats:italic>Zea mays</jats:italic> L.), one of the most highly produced cereal crops worldwide, would have a global impact on human health. <jats:italic>PLASTID TERMINAL OXIDASE</jats:italic> (<jats:italic>PTOX</jats:italic>) genes play an important role in carotenoid metabolism; however, the possible function of <jats:italic>PTOX</jats:italic> in carotenoid biosynthesis in maize has not yet been explored. In this study, we characterized the maize <jats:italic>PTOX</jats:italic> locus by forward‐ and reverse‐genetic analyses. While most higher plant species possess a single copy of the <jats:italic>PTOX</jats:italic> gene, maize carries two tandemly duplicated copies. Characterization of mutants revealed that disruption of either copy resulted in a carotenoid‐deficient phenotype. We identified mutations in the <jats:italic>PTOX</jats:italic> genes as being causal of the classic maize mutant, <jats:italic>albescent1</jats:italic>. Remarkably, overexpression of <jats:italic>ZmPTOX1</jats:italic> significantly improved the content of carotenoids, especially β‐carotene (provitamin A), which was increased by ~threefold, in maize kernels. Overall, our study shows that maize <jats:italic>PTOX</jats:italic> locus plays an important role in carotenoid biosynthesis in maize kernels and suggests that fine‐tuning the expression of this gene could improve the nutritional value of cereal grains.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>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. In this study, we verified that low‐temperature treatment promoted soluble sugar accumulation in apple fruit and found that this was due to the upregulation of the Tonoplast Sugar Transporter genes <jats:italic>MdTST1/2.</jats:italic> A combined strategy using assay for transposase‐accessible chromatin (ATAC) sequencing and gene expression and <jats:italic>cis</jats:italic>‐acting elements analyses, we identified two C‐repeat Binding Factors, <jats:italic>MdCBF1</jats:italic> and <jats:italic>MdCBF2</jats:italic>, that were induced by low temperature and that might be upstream transcription factors of <jats:italic>MdTST1/2</jats:italic>. Further studies established that MdCBF1/2 could bind to the promoters of <jats:italic>MdTST1/2</jats:italic> and activate their expression. Overexpression of <jats:italic>MdCBF1</jats:italic> or <jats:italic>MdCBF2</jats:italic> in apple calli and fruit significantly upregulated <jats:italic>MdTST1</jats:italic>/<jats:italic>2</jats:italic> expression and increased the concentrations of glucose, fructose, and sucrose. Suppression of <jats:italic>MdTST1</jats:italic> and/or <jats:italic>MdTST2</jats:italic> in an <jats:italic>MdCBF1/2</jats:italic>‐overexpression background abolished the positive effect of <jats:italic>MdCBF1/2</jats:italic> on sugar accumulation. In addition, simultaneous silencing of <jats:italic>MdCBF1/2</jats:italic> downregulated <jats:italic>MdTST1/2</jats:italic> expression and apple fruits failed to accumulate more sugars under low‐temperature conditions, indicating that <jats:italic>MdCBF1/2</jats:italic>‐mediated sugar accumulation was dependent on <jats:italic>MdTST1/2</jats:italic> expression. Hence, we concluded that the <jats:italic>MdCBF1/2</jats:italic>‐<jats:italic>MdTST1/2</jats:italic> module is crucial for sugar accumulation in apples in response to low temperatures. Our findings provide mechanistic components coordinating the relationship between low temperature and sugar accumulation as well as new avenues to improve fruit quality.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p><jats:italic>Cryptotaenia japonica</jats:italic>, a traditional medicinal and edible vegetable crops, is well‐known for its attractive flavors and health care functions. As a member of the Apiaceae family, the evolutionary trajectory and biological properties of <jats:italic>C. japonica</jats:italic> are not clearly understood. Here, we first reported a high‐quality genome of <jats:italic>C. japonica</jats:italic> with a total length of 427 Mb and N50 length 50.76 Mb, was anchored into 10 chromosomes, which confirmed by chromosome (cytogenetic) analysis. Comparative genomic analysis revealed <jats:italic>C. japonica</jats:italic> exhibited low genetic redundancy, contained a higher percentage of single‐cope gene families. The homoeologous blocks, <jats:italic>K</jats:italic><jats:sub>s</jats:sub>, and collinearity were analyzed among Apiaceae species contributed to the evidence that <jats:italic>C. japonica</jats:italic> lacked recent species‐specific WGD. Through comparative genomic and transcriptomic analyses of Apiaceae species, we revealed the genetic basis of the production of anthocyanins. Several structural genes encoding enzymes and transcription factor genes of the anthocyanin biosynthesis pathway in different species were also identified. The <jats:italic>CjANSa</jats:italic>, <jats:italic>CjDFRb</jats:italic>, and <jats:italic>CjF3H</jats:italic> gene might be the target of <jats:italic>Cjaponica_2.2062</jats:italic> (<jats:italic>bHLH</jats:italic>) and <jats:italic>Cjaponica_1.3743</jats:italic> (<jats:italic>MYB</jats:italic>). Our findings provided a high‐quality reference genome of <jats:italic>C. japonica</jats:italic> and offered new insights into Apiaceae evolution and biology.</jats:p>

<jats:title>SUMMARY</jats:title><jats:p>Current climate change brings with it a higher frequency of environmental stresses, which occur in combination rather than individually leading to massive crop losses worldwide. In addition to, for example, drought stress (low water availability), also flooding (excessive water) can threaten the plant, causing, among others, an energy crisis due to hypoxia, which is responded to by extensive transcriptional, metabolic and growth‐related adaptations. While signalling during flooding is relatively well understood, at least in model plants, the molecular mechanisms of combinatorial flooding stress responses, for example, flooding simultaneously with salinity, temperature stress and heavy metal stress or sequentially with drought stress, remain elusive. This represents a significant gap in knowledge due to the fact that dually stressed plants often show unique responses at multiple levels not observed under single stress. In this review, we (i) consider possible effects of stress combinations from a theoretical point of view, (ii) summarize the current state of knowledge on signal transduction under single flooding stress, (iii) describe plant adaptation responses to flooding stress combined with four other abiotic stresses and (iv) propose molecular components of combinatorial flooding (hypoxia) stress adaptation based on their reported dual roles in multiple stresses. This way, more future emphasis may be placed on deciphering molecular mechanisms of combinatorial flooding stress adaptation, thereby potentially stimulating development of molecular tools to improve plant resilience towards multi‐stress scenarios.</jats:p>