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result(s) for
"Photoperiod"
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Strong photoperiod sensitivity is controlled by cooperation and competition among Hd1, Ghd7 and DTH8 in rice heading
• Rice (Oryza sativa) is a short-day (SD) plant originally having strong photoperiod sensitivity (PS), with SDs promoting and long days (LDs) suppressing flowering. Although the evolution of PS in rice has been extensively studied, there are few studies that combine the genetic effects and underlying mechanism of different PS gene combinations with variations in PS.
• We created a set of isogenic lines among the core PS-flowering genes Hd1, Ghd7 and DTH8 using CRISPR mutagenesis, to systematically dissect their genetic relationships under different day-lengths. We investigated their monogenic, digenic, and trigenic effects on target gene regulation and PS variation.
• We found that Hd1 and Ghd7 have the primary functions for promoting and repressing flowering, respectively, regardless of day-length. However, under LD conditions, Hd1 promotes Ghd7 expression and is recruited by Ghd7 and/or DTH8 to form repressive complexes that collaboratively suppress the Ehd1-Hd3a/RFT1 pathway to block heading, but under SD conditions Hd1 competes with the complexes to promote Hd3a/RFT1 expression, playing a tradeoff relationship with PS flowering. Natural allelic variations of Hd1, Ghd7 and DTH8 in rice populations have resulted in various PS performances.
• Our findings reveal that rice PS flowering is controlled by crosstalk of two modules – Hd1–Hd3a/RFT1 in SD conditions and (Hd1/Ghd7/DTH8)–Ehd1–Hd3a/RFT1 in LD conditions – and the divergences of these genes provide the basis for rice adaptation to broad regions.
Journal Article
OsMT2b Regulates Pollen Development and ROS Homeostasis in a Photoperiod‐Dependent Manner
Reactive oxygen species (ROS) are signalling molecules that promote programmed cell death in animal and plant systems. However, their role in rice (Oryza sativa L.) anther development is unclear. In this study, we show that lower transcript levels of the metallothionein gene OsMT2b in japonica rice plants obtained by RNA interference (RNAi) resulted in a serious reduction in the seed setting rate. Observations of semi‐thin sections of anthers indicated that tapetum degradation initiates early and ends late in OsMT2b‐RNAi plants relative to the wild type (WT). Nitroblue tetrazolium staining and measurements of hydrogen peroxide contents showed that ROS contents are higher in OsMT2b‐RNAi plants than in WT. Terminal‐deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assays showed that abnormal programmed cell death in the tapetum results in sterile microspores. In addition, the OsMT2b‐RNAi plants were sensitive to photoperiod; they were sterile under natural long‐day conditions but almost fully fertile under natural short‐day conditions, indicating that OsMT2b integrates photoperiod information into pollen development. The discovery of this rice material may enrich germplasm resources for two‐line hybrid rice breeding, and further research may enable its application in two‐line hybrid rice breeding.
Journal Article
The Photoperiod: Handling and Causing Stress in Plants
The photoperiod, which is the length of the light period in the diurnal cycle of 24 h, is an important environmental signal. Plants have evolved sensitive mechanisms to measure the length of the photoperiod. Photoperiod sensing enables plants to synchronize developmental processes, such as the onset of flowering, with a specific time of the year, and enables them to alleviate the impact of environmental stresses occurring at the same time every year. During the last years, the importance of the photoperiod for plant responses to abiotic and biotic stresses has received increasing attention. In this review, we summarize the current knowledge on the signaling pathways involved in the photoperiod-dependent regulation of responses to abiotic (freezing, drought, osmotic stress) and biotic stresses. A central role of GIGANTEA (GI), which is a key player in the regulation of photoperiod-dependent flowering, in stress responses is highlighted. Special attention is paid to the role of the photoperiod in regulating the redox state of plants. Furthermore, an update on photoperiod stress, which is caused by sudden alterations in the photoperiod, is given. Finally, we will review and discuss the possible use of photoperiod-induced stress as a sustainable resource to enhance plant resistance to biotic stress in horticulture.
Journal Article
Transcriptome and WGCNA reveals the potential genetic basis of photoperiod-sensitive male sterility in soybean
Background
Soybean (
Glycine max
(L.) Merr.) is a crucial crop due to its high plant protein and oil content. Previous studies have shown that soybeans exhibit significant heterosis in terms of yield and protein content However, the practical application of soybean heterosis remains difficult, as the molecular mechanisms underlying photoperiod-sensitive genic male sterile (PGMS) is still unclear.
Results
This study characterized the PGMS line 88-428BY, which is sterile under short-day (SD) conditions and fertile under long-day (LD) conditions. To elucidate the genetic basis for this trait, we collected anthers, from 88-428BY under SD and LD conditions at three developmental stages, resulting in the identification of differentially expressed genes (DEGs) (2333, 2727 and 7282 DEGs, respectively) using Illumina transcriptome analysis. Using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses, we fund that among the DEGs, enriched genes were associated with photoperiod stress, light stimulus, oxidation-reduction processes, multicellular organism development and protein phosphorylation. Additionally, weighted correlation network analysis identified four modules (blue, brown, red, and yellow) that were significantly correlated with PGMS, revealing co-expressed hub genes with potential regulatory roles. Functional annotation of 224 DEGs with|KME| >0.9 across the four modules in seven databases highlighted their involvement in light stimulus, oxidation-reduction processes, multicellular organism development, and protein phosphorylation, suggesting their importance in soybean PGMS. By integrating fertility-related genes previously identified by other studies with the DEGs from our analysis, we identified eight candidate genes associated with the photosensitive sterility in soybeans.
Conclusions
This study enhances the understanding of PGMS in soybean and establishes the genetic basis for a two-line hybrid seed production system in soybean.
Journal Article
Stepwise increases in FT1 expression regulate seasonal progression of flowering in wheat (Triticum aestivum)
• Flowering is regulated by genes that respond to changing daylengths and temperature, which have been well studied using controlled conditions; however, the molecular processes underpinning flowering in nature remain poorly understood.
• Here, we investigate the genetic pathways that coordinate flowering and inflorescence development of wheat (Triticum aestivum) as daylengths extend naturally in the field, using lines that contain variant alleles for the key photoperiod gene, Photoperiod-1 (Ppd-1).
• We found flowering involves a stepwise increase in the expression of FLOWERING LOCUS T1 (FT1), which initiates under day-neutral conditions of early spring. The incremental rise in FT1 expression is overridden in plants that contain a photoperiod-insensitive allele of Ppd-1, which hastens the completion of spikelet development and accelerates flowering time. The accelerated inflorescence development of photoperiod-insensitive lines is promoted by advanced seasonal expression of floral meristem identity genes. The completion of spikelet formation is promoted by FLOWERING LOCUS T2, which regulates spikelet number and is activated by Ppd-1.
• In wheat, flowering under natural photoperiods is regulated by stepwise increases in the expression of FT1, which responds dynamically to extending daylengths to promote early inflorescence development. This research provides a strong foundation to improve yield potential by fine-tuning the photoperiod-dependent control of inflorescence development.
Journal Article
Comparative transcriptome analysis of oat varieties with different flowering performances under a short-day photoperiod
Background
Insensitivity to day length is an essential trait for oat cultivation and its geographical spread to a wide range of latitudes. Daylength-insensitive oat cultivars can flower normally from low to high latitudes and may be especially well suited for a double-cropping system. However, few studies have investigated the regulatory mechanisms involved in flowering in photoperiod-insensitive oats.
Results
In this study, we compared the developmental stages of shoot apical meristems (SAMs) and transcriptome profiles between the photoperiod-insensitive oat cultivar VAO-8 and the photoperiod-sensitive oat cultivar Baiyan 2 at four time points under a short-day photoperiod. The development of Baiyan 2 was affected by short-day length, and SAMs persisted in the vegetative stage. VAO-8 responded less to photoperiod and matured normally under a short-day photoperiod. Comparative transcriptome data of the two cultivars revealed a total of 824, 1,189, 646 and 1,145 differentially expressed genes (DEGs) between VAO-8 and Baiyan 2 at four time points. Functional enrichment analysis revealed that metabolic processes related to chlorophyll biosynthesis, photosynthesis, carbohydrate metabolism and the secondary metabolism were significantly enhanced in VAO-8 compared with those in Baiyan 2. The upregulated genes involved in these processes may contribute to the flowering of VAO-8 under a short-day photoperiod. Furthermore, the differential expression of 93 transcription factor genes involved in multiple flowering pathways was observed, and these genes may play important roles in the regulation of VAO-8 flowering.
Conclusions
The results provide a comprehensive understanding of the photoperiod-insensitive molecular mechanism of oats at the transcriptional level under a short-day photoperiod, which lay a foundation for breeding photoperiod-insensitive oat cultivars.
Journal Article
Temperature and photoperiod drive spring phenology across all species in a temperate forest community
Accurate predictions of spring plant phenology with climate change are critical for projections of growing seasons, plant communities and a number of ecosystem services, including carbon storage. Progress towards prediction, however, has been slow because the major cues known to drive phenology – temperature (including winter chilling and spring forcing) and photoperiod – generally covary in nature and may interact, making accurate predictions of plant responses to climate change complex and nonlinear. Alternatively, recent work suggests many species may be dominated by one cue, which would make predictions much simpler.
Here, we manipulated all three cues across 28 woody species from two North American forests.
All species responded to all cues examined. Chilling exerted a strong effect, especially on budburst (−15.8 d), with responses to forcing and photoperiod greatest for leafout (−19.1 and −11.2 d, respectively). Interactions between chilling and forcing suggest that each cue may compensate somewhat for the other. Cues varied across species, leading to staggered leafout within each community and supporting the idea that phenology is a critical aspect of species’ temporal niches.
Our results suggest that predicting the spring phenology of communities will be difficult, as all species we studied could have complex, nonlinear responses to future warming.
Journal Article
DNA methylation pattern of Photoperiod-B1 is associated with photoperiod insensitivity in wheat (Triticum aestivum)
As one of the three key components of the ‘Green Revolution’, photoperiod insensitivity is vital for improved adaptation of wheat (Triticum aestivum) cultivars to a wider geographical range. Photoperiod-B1a (Ppd-B1a) is one of the major genes that confers photoperiod insensitivity in ‘Green Revolution’ varieties, and has made a significant contribution to wheat yield improvement.
In this study, we investigated the mechanisms underlying the photoperiod insensitivity of Ppd-B1a alleles from an epigenetic perspective using a combination of bisulfite genomic sequencing, orthologous comparative analysis, association analysis, linkage analysis and gene expression analysis.
Based on the study of a large collection of wheat germplasm, we report two methylation haplotypes of Ppd-B1 and demonstrate that the higher methylation haplotype (haplotype a) was associated with increased copy numbers and higher expression levels of the Ppd-B1 gene, earlier heading and photoperiod insensitivity. Furthermore, assessment of the distribution frequency of the different methylation haplotypes suggested that the methylation patterns have undergone selection during the wheat breeding process.
Our study suggests that DNA methylation in the regulatory region of the Ppd-B1 alleles, which is closely related to copy number variation, plays a significant role in wheat breeding, to confer photoperiod insensitivity and better adaptation to a wider geographical range.
Journal Article
Stepwise selection on homeologous PRR genes controlling flowering and maturity during soybean domestication
Adaptive changes in plant phenology are often considered to be a feature of the so-called ‘domestication syndrome’ that distinguishes modern crops from their wild progenitors, but little detailed evidence supports this idea. In soybean, a major legume crop, flowering time variation is well characterized within domesticated germplasm and is critical for modern production, but its importance during domestication is unclear. Here, we identify sequential contributions of two homeologous pseudo-response-regulator genes,
Tof12
and
Tof11
, to ancient flowering time adaptation, and demonstrate that they act via
LHY
homologs to promote expression of the legume-specific
E1
gene and delay flowering under long photoperiods. We show that
Tof12
-dependent acceleration of maturity accompanied a reduction in dormancy and seed dispersal during soybean domestication, possibly predisposing the incipient crop to latitudinal expansion. Better understanding of this early phase of crop evolution will help to identify functional variation lost during domestication and exploit its potential for future crop improvement.
Whole-genome resequencing and association analyses in 424 soybean accessions identify two homeologous genes that contributed to flowering time adaptation during soybean domestication.
Journal Article