light responses
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2021 ◽  
Author(s):  
Chi Sun ◽  
Xiaodong Zhang ◽  
Philip Andrew Ruzycki ◽  
Shiming Chen

MLL1 (KMT2A) and MLL2 (KMT2B) are homologous members of the mixed-lineage leukemia (MLL) family of histone methyltransferases involved in epigenomic transcriptional regulation. Their sequence variants have been associated with neurological and psychological disorders, but little is known about their roles and mechanism of action in CNS development. Using mouse retina as a model, we previously reported the roles of MLL1 in retinal neurogenesis and horizontal cell maintenance. Here we determine roles of MLL2 and MLL1/MLL2 together in retinal development using conditional knockout (CKO) mice. Deleting Mll2 from Chx10+ retinal progenitors resulted in a similar phenotype as Mll1 CKO, but removal of both alleles produced much more severe deficits than each single CKO: 1-month double CKO mutants displayed null light responses in electroretinogram; thin retinal layers, including shorter photoreceptor outer segments with impaired phototransduction gene expression; and reduced numbers of M-cones, horizontal and amacrine neurons, followed by fast retinal degeneration. Despite moderately reduced progenitor cell proliferation at P0, the neurogenic capacity was largely maintained in double CKO mutants. However, upregulated apoptosis and reactive gliosis were detected during postnatal retinal development. Finally, the removal of both MLLs in fated rods produced a normal phenotype, but the CKO in M-cones impaired M-cone function and survival, indicating both cell non-autonomous and autonomous mechanisms. Altogether, our results suggest that MLL1/MLL2 play redundant roles in maintaining specific retinal neurons after cell fate specification and are essential for establishing functional neural networks.


2021 ◽  
Vol 8 ◽  
Author(s):  
Mingyu Ma ◽  
Mingyu Zhong ◽  
Quansheng Zhang ◽  
Wei Zhao ◽  
Mengxin Wang ◽  
...  

Chalcone synthase (CHS) family are plant type III polyketide synthases that participate in the flavonoid synthesis pathway to induce plant resistance to various biotic and abiotic stresses. Zostera marina, a common seagrass, migrated to terrestrial conditions and returned to the sea, achieving the most severe habitat shift of flowering plants. Given the special evolutionary process, we conducted genome-wide, expression and enzyme activity analyses of the ZosmaCHS family to understand its phylogenetic implications. Various duplication modes led to the expansion of 11 CHS homologs in Z. marina. Based on the phylogenetic relationships, ZosmaCHSs were classified into three clades. Further quantitative real time-PCR analyses of the ZosmaCHS homologs showed different light responses and tissue-specific expression, indicating functional diversification of the ZosmaCHSs. Moreover, the ZosmaCHS proteins clustering with the validated chalcone synthases were recombined into prokaryotic expression systems. All the recombinant proteins showed CHS activity to generate naringenin chalcone with varying catalytic efficiencies. ZosmaCHS07 was regarded as the dominant CHS because of its significant light response and the higher catalytic efficiency. Taken together, the disparity of the expression and enzyme activity indicated that sub-functionalization is the primary mechanism of the expansion of the ZosmaCHSs family.


2021 ◽  
Vol 289 ◽  
pp. 110488
Author(s):  
Jiaxin Wang ◽  
Linlin Liu ◽  
Qianhui Tang ◽  
Kang Sun ◽  
Liang Zeng ◽  
...  

2021 ◽  
Vol 12 ◽  
Author(s):  
Enrique Pola-Sánchez ◽  
José Manuel Villalobos-Escobedo ◽  
Nohemí Carreras-Villaseñor ◽  
Pedro Martínez-Hernández ◽  
Emma Beatriz Beltrán-Hernández ◽  
...  

Light provides critical information for the behavior and development of basically all organisms. Filamentous fungi sense blue light, mainly, through a unique transcription factor complex that activates its targets in a light-dependent manner. In Trichoderma atroviride, the BLR-1 and BLR-2 proteins constitute this complex, which triggers the light-dependent formation of asexual reproduction structures (conidia). We generated an ENVOY photoreceptor mutant and performed RNA-seq analyses in the mutants of this gene and in those of the BLR-1, CRY-1 and CRY-DASH photoreceptors in response to a pulse of low intensity blue light. Like in other filamentous fungi BLR-1 appears to play a central role in the regulation of blue-light responses. Phenotypic characterization of the Δenv-1 mutant showed that ENVOY functions as a growth and conidiation checkpoint, preventing exacerbated light responses. Similarly, we observed that CRY-1 and CRY-DASH contribute to the typical light-induced conidiation response. In the Δenv-1 mutant, we observed, at the transcriptomic level, a general induction of DNA metabolic processes and strong repression of central metabolism. An analysis of the expression level of DNA repair genes showed that they increase their expression in the absence of env-1. Consistently, photoreactivation experiments showed that Δenv-1 had increased DNA repair capacity. Our results indicate that light perception in T. atroviride is far more complex than originally thought.


2021 ◽  
Author(s):  
Lachlan Kay ◽  
Rebecca Keogh ◽  
Thomas Andrillon ◽  
Joel Pearson

The pupillary light response is an important automatic physiological response that optimises light reaching the retina. Recent work has shown that the pupil also adjusts in response to illusory brightness and a range of cognitive functions, however, it remains unclear what exactly drives these endogenous changes. Here we show that the imagery pupillary light response correlates with objective measures of sensory imagery strength. Further, the trial-by-trial phenomenological vividness of visual imagery is tracked by the imagery pupillary light response. We also demonstrated that there was no evidence for an imagery pupillary light response in a group of individuals without visual imagery (aphantasia), however, they did show perceptual pupil light responses and pupil dilation with larger cognitive load. Our results provide evidence that the pupillary light response indexes the sensory strength of visual imagery and also provides the first physiological validation of aphantasia.


2021 ◽  
Vol 12 ◽  
Author(s):  
Daniel Matsusaka ◽  
Daniele Filiault ◽  
Diego H. Sanchez ◽  
Javier F. Botto

Arabidopsis thaliana shows a wide range of genetic and trait variation among wild accessions. Because of its unparalleled biological and genomic resources, Arabidopsis has a high potential for the identification of genes underlying ecologically important complex traits, thus providing new insights on genome evolution. Previous research suggested that distinct light responses were crucial for Arabidopsis establishment in a peculiar ecological niche of southern Patagonia. The aim of this study was to explore the genetic basis of contrasting light-associated physiological traits that may have mediated the rapid adaptation to this new environment. From a biparental cross between the photomorphogenic contrasting accessions Patagonia (Pat) and Columbia (Col-0), we generated a novel recombinant inbred line (RIL) population, which was entirely next-generation sequenced to achieve ultra-high-density saturating molecular markers resulting in supreme mapping sensitivity. We validated the quality of the RIL population by quantitative trait loci (QTL) mapping for seedling de-etiolation, finding seven QTLs for hypocotyl length in the dark and continuous blue light (Bc), continuous red light (Rc), and continuous far-red light (FRc). The most relevant QTLs, Rc1 and Bc1, were mapped close together to chromosome V; the former for Rc and Rc/dark, and the latter for Bc, FRc, and dark treatments. The additive effects of both QTLs were confirmed by independent heterogeneous inbred families (HIFs), and we explored TZP and ABA1 as potential candidate genes for Rc1 and Bc1QTLs, respectively. We conclude that the Pat × Col-0 RIL population is a valuable novel genetic resource to explore other adaptive traits in Arabidopsis.


2021 ◽  
pp. 2100127
Author(s):  
Kevin J. Cao ◽  
Elijah F. Lyons ◽  
Benjamin E. Smith ◽  
Bristol L. Denlinger ◽  
Hong Ma ◽  
...  

2021 ◽  
Vol 12 ◽  
Author(s):  
Jae Young Kim ◽  
June-Hee Lee ◽  
Chung-Mo Park

Light acts as a vital external cue that conveys surrounding information into plant growth and performance to facilitate plants to coordinate with changing environmental conditions. Upon exposure to light illumination, plants trigger a burst of molecular and physiological signaling cascades that induces not only photomorphogenic responses but also diverse adaptive behaviors. Notably, light responses and photomorphogenic traits are often associated with plant responses to other environmental cues, such as heat, cold, drought, and herbivore and pathogen attack. Growing evidence in recent years demonstrate that the red/far-red light-absorbing phytochrome (phy) photoreceptors, in particular phyB, play an essential role in plant adaptation responses to abiotic and biotic tensions by serving as a key mediator of information flow. It is also remarkable that phyB mediates the plant priming responses to numerous environmental challenges. In this minireview, we highlight recent advances on the multifaceted role of phyB during plant environmental adaptation. We also discuss the biological relevance and efficiency of the phy-mediated adaptive behaviors in potentially reducing fitness costs under unfavorable environments.


2021 ◽  
Author(s):  
Umidjon Shapulatov ◽  
Mara Meisenburg ◽  
mark van hoogdalem ◽  
Alexander van Hall ◽  
Wim Van Ieperen ◽  
...  

Arabidopsis has five phytochrome (PHY) genes for sensing the Red:Far Red (R:FR) ratio in ambient light, of which PHYA has an established role in responses to FR. To study whether and how PHYs may influence each other's transcription, PHY-Luciferase reporter plants (pPHYA:LUC, pPHYB:LUC, pPHYC:LUC, pPHYD:LUC and pPHYE:LUC) were constructed. Subsequently, reporter lines representative for each PHY were crossed into each of the five single phy-mutant backgrounds. Reporter activities in WT and phy mutant was studied under diurnal mixed (R, B, FR), R, FR or B LED light in seedling or rosette plants. Both pPHYA:LUC and pPHYB:LUC show strong induction under FR. Full FR upregulation of both PHYA and PHYB is dependent on PHYE, identifying PHYE as a novel sensor for FR light responses. Results also show that PHYA expression is strongly suppressed by PHYD. Results were confirmed for expression of endogenous PHYA and PHYB, albeit with different dynamics compared to the LUC reporters. Profiling of pPHYA:LUC and pPHYB:LUC reporters suggest gating of FR responses. Manipulation of PHY expression levels by FR may provide a novel basis for manipulating plant growth in controlled environments.


2021 ◽  
Vol 12 ◽  
Author(s):  
Susan J. Murch ◽  
Lauren A. E. Erland

Melatonin (N-acetyl-5-methoxy-tryptamine) is a mammalian neurohormone, antioxidant and signaling molecule that was first discovered in plants in 1995. The first studies investigated plant melatonin from a human perspective quantifying melatonin in foods and medicinal plants and questioning whether its presence could explain the activity of some plants as medicines. Starting with these first handful of studies in the late 1990s, plant melatonin research has blossomed into a vibrant and active area of investigation and melatonin has been found to play critical roles in mediating plant responses and development at every stage of the plant life cycle from pollen and embryo development through seed germination, vegetative growth and stress response. Here we have utilized a systematic approach in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) protocols to reduce bias in our assessment of the literature and provide an overview of the current state of melatonin research in plants, covering 1995–2021. This review provides an overview of the biosynthesis and metabolism of melatonin as well as identifying key themes including: abiotic stress responses, root development, light responses, interkingdom communication, phytohormone and plant signaling. Additionally, potential biases in the literature are investigated and a birefringence in the literature between researchers from plant and medical based which has helped to shape the current state of melatonin research. Several exciting new opportunities for future areas of melatonin research are also identified including investigation of non-crop and non-medicinal species as well as characterization of melatonin signaling networks in plants.


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