scholarly journals Genetic mechanisms in the repression of flowering by gibberellins in apple (Malus x domestica Borkh.)

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Songwen Zhang ◽  
Christopher Gottschalk ◽  
Steve van Nocker
Keyword(s):  
Shoot Apex ◽  
Higher Plants ◽  
Sequence Data ◽  
Feedback Regulation ◽  
Shoot Elongation ◽  
Auxin Signaling ◽  
Flower Formation ◽  
Node Number ◽  
Woody Perennial ◽  
Genetic Mechanisms

Abstract Background Gibberellins (GAs) can have profound effects on growth and development in higher plants. In contrast to their flowering-promotive role in many well-studied plants, GAs can repress flowering in woody perennial plants such as apple (Malus x domestica Borkh.). Although this effect of GA on flowering is intriguing and has commercial importance, the genetic mechanisms linking GA perception with flowering have not been well described. Results Application of a mixture of bioactive GAs repressed flower formation without significant effect on node number or shoot elongation. Using Illumina-based transcriptional sequence data and a newly available, high-quality apple genome sequence, we generated transcript models for genes expressed in the shoot apex, and estimated their transcriptional response to GA. GA treatment resulted in downregulation of a diversity of genes participating in GA biosynthesis, and strong upregulation of the GA catabolic GA2 OXIDASE genes, consistent with GA feedback and feedforward regulation, respectively. We also observed strong downregulation of numerous genes encoding potential GA transporters and receptors. Additional GA-responsive genes included potential components of cytokinin (CK), abscisic acid (ABA), brassinosteroid, and auxin signaling pathways. Finally, we observed rapid and strong upregulation of both of two copies of a gene previously observed to inhibit flowering in apple, MdTFL1 (TERMINAL FLOWER 1). Conclusion The rapid and robust upregulation of genes associated with GA catabolism in response to exogenous GA, combined with the decreased expression of GA biosynthetic genes, highlights GA feedforward and feedback regulation in the apple shoot apex. The finding that genes with potential roles in GA metabolism, transport and signaling are responsive to GA suggests GA homeostasis may be mediated at multiple levels in these tissues. The observation that TFL1-like genes are induced quickly in response to GA suggests they may be directly targeted by GA-responsive transcription factors, and offers a potential explanation for the flowering-inhibitory effects of GA in apple. These results provide a context for investigating factors that may transduce the GA signal in apple, and contribute to a preliminary genetic framework for the repression of flowering by GAs in a woody perennial plant.

Molecular Systematics of Tribe Physarieae (Brassicaceae) Based on Nuclear ITS, LUMINIDEPENDENS, and Chloroplast ndhF

2021 ◽  
Author(s):  
Sara Fuentes-Soriano ◽  
Elizabeth A. Kellogg
Keyword(s):  
Sequence Data ◽  
Plastid Dna ◽  
Sister Relationship ◽  
Data Set ◽  
Woody Perennial ◽  
History Of ◽  
Nuclear Its ◽  
Phylogenetic Framework ◽  
Phylogenetic Hypotheses ◽  
Relationship Of

Physarieae is a small tribe of herbaceous annual and woody perennial mustards that are mostly endemic to North America, with its members including a large amount of variation in floral, fruit, and chromosomal variation. Building on a previous study of Physarieae based on morphology and ndhF plastid DNA, we reconstructed the evolutionary history of the tribe using new sequence data from two nuclear markers, and compared the new topologies against previously published cpDNA-based phylogenetic hypotheses. The novel analyses included ca. 420 new sequences of ITS and LUMINIDEPENDENS (LD) markers for 39 and 47 species, respectively, with sampling accounting for all seven genera of Physarieae, including nomenclatural type species, and 11 outgroup taxa. Maximum parsimony, maximum likelihood, and Bayesian analyses showed that these additional markers were largely consistent with the previous ndhF data that supported the monophyly of Physarieae and resolved two major clades within the tribe, i.e., DDNLS (Dithyrea, Dimorphocarpa, Nerisyrenia, Lyrocarpa, and Synthlipsis)and PP (Paysonia and Physaria). New analyses also increased internal resolution for some closely related species and lineages within both clades. The monophyly of Dithyrea and the sister relationship of Paysonia to Physaria was consistent in all trees, with the sister relationship of Nerisyrenia to Lyrocarpa supported by ndhF and ITS, and the positions of Dimorphocarpa and Synthlipsis shifted within the DDNLS Clade depending on the employed data set. Finally, using the strong, new phylogenetic framework of combined cpDNA + nDNA data, we discussed standing hypotheses of trichome evolution in the tribe suggested by ndhF.

scholarly journals Metabolic regulation of photosynthetic membrane structure tunes electron transfer function

2018 ◽  
Vol 475 (7) ◽  
pp. 1225-1233 ◽  
Author(s):  
Matthew P. Johnson
Keyword(s):  
Electron Transfer ◽  
Metabolic Regulation ◽  
Higher Plants ◽  
Three Dimensional ◽  
Feedback Regulation ◽  
Membrane Dynamics ◽  
Dimensional Structure ◽  
Photosynthetic Membrane ◽  
Light Harvesting Complex ◽  
Light Harvesting Complex Ii

The photosynthetic chloroplast thylakoid membrane of higher plants is a complex three-dimensional structure that is morphologically dynamic on a timescale of just a few minutes. The membrane dynamics are driven by the phosphorylation of light-harvesting complex II (LHCII) by the STN7 kinase, which controls the size of the stacked grana region relative to the unstacked stromal lamellae region. Here, I hypothesise that the functional significance of these membrane dynamics is in controlling the partition of electrons between photosynthetic linear and cyclic electron transfer (LET and CET), which determines the ratio of NADPH/ATP produced. The STN7 kinase responds to the metabolic state of the chloroplast by sensing the stromal redox state. A high NADPH/ATP ratio leads to reduction of thioredoxin f (TRXf), which reduces a CxxxC motif in the stromal domain of STN7 leading to its inactivation, whereas a low NADPH/ATP ratio leads to oxidation of TRXf and STN7 activation. Phosphorylation of LHCII leads to smaller grana, which favour LET by speeding up diffusion of electron carriers plastoquinone (PQ) and plastocyanin (PC) between the domains. In contrast, dephosphorylation of LHCII leads to larger grana that slow the diffusion of PQ and PC, leaving the PQ pool in the stroma more oxidised, thus enhancing the efficiency of CET. The feedback regulation of electron transfer by the downstream metabolism is crucial to plant fitness, since perturbations in the NADPH/ATP ratio can rapidly lead to the inhibition of photosynthesis and photo-oxidative stress.

Regulation in Lolium temulentum of the Metabolism of Gibberellin A20 and Gibberellin A1 by 16,17-Dihydro GA5 and by the Growth Retardant, LAB 198 999

1997 ◽  
Vol 24 (3) ◽  
pp. 359 ◽  
Author(s):  
O. Junttila ◽  
R.W. King ◽  
A. Poole ◽  
G. Kretschmer ◽  
R.P. Pharis ◽  
...  
Keyword(s):  
Growth Retardation ◽  
Higher Plants ◽  
Shoot Elongation ◽  
Stem Growth ◽  
Growth Retardant ◽  
Shoot Tips ◽  
Stem Tissue ◽  
Lolium Temulentum ◽  
Gibberellin A1 ◽  
Excised Tissue

The ring D-modified gibberellin [GA], 16,17-dihydro GA5, can retard stem growth in Lolium temulentum L. while promoting flowering (Evans et al., 1994, Planta193, 107–114). Using [1,2,3-3 H]GA20 to study the final biosynthetic step to GA1 (a known effector of shoot elongation in higher plants), it was shown that C-3b-hydroxylation of GA20 to GA1 is blocked by 16,17-dihydro GA5 but is little affected by GA5. Another late-stage biosynthetic inhibitor, the acylcyclohexanedione, LAB 198 999, also blocked GA1 formation. Furthermore, endogenous levels of GA20 built up after application of 16,17-dihydro GA5. Consequently, growth retardation by 16,17-dihydro GA5 and LAB 198 999 is likely to be the result of their inhibition of GA20 3b-hydroxylation to GA1. Another fate for GA20 in Lolium is its C-2b-hydroxylation to growth-inactive GA29. This conversion was also inhibited by 16,17-dihydro GA5 but less so by LAB 198 999. The analogous step involving 2b-hydroxylation of GA1 to GA8 appeared to be insensitive to either growth retardant. When [3H]GA20 was injected into the cavity within the young intact sheathing leaves, there was an appreciable metabolism of this GA20 to GA1 and thence to GA8 (ca 10% and 30% respectively within 5 h). For excised shoot tips, however, [3H]GA20 was converted rapidly and virtually completely to GA29 in 3–5 h. Interestingly, with these excised shoot tips, GA3 and GA5 as well as 16,17-dihydro GA5 when applied via the agar strongly inhibited 2b-hydroxylation of GA20 to GA29. In contrast, while 16,17-dihydro GA5 blocked GA20 metabolism to GA29 in intact sheath/stem tissue, this conversion was not inhibited by GA5. These differences in structural specificity for GAs which inhibit 2b-hydroxylation as opposed to 3b-hydroxylation are in accordance with these two Ring-A hydroxylation steps being catalysed by different enzymes. Finally, the differences in GA20 metabolism between intact versus excised tissue raise the possibility that tissue wounding with excision enhanced the activity of the GA20 2b-hydroxylase(s).

scholarly journals Transcriptome-wide analysis of auxin-induced carotenoid accumulation in Chlorella microalgae

2018 ◽  
Author(s):  
Faisal Alsenani ◽  
Taylor J. Wass ◽  
Ruijuan Ma ◽  
Eladl Eltanahy ◽  
Michael E. Netzel ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Abscisic Acid ◽  
De Novo ◽  
Higher Plants ◽  
Abiotic Stress Tolerance ◽  
Auxin Signaling ◽  
Rna Seq ◽  
Carotenoid Accumulation ◽  
Close Relationship ◽  
Indole 3 Acetic Acid

AbstractMicroalgae are a commercially viable route for the production of carotenoids, including β-carotene and astaxanthin. In the current study, the commercially relevant microalga, Chlorella sp. BR2 was treated with four plant hormones: indole-3-acetic acid, salicylic acid, abscisic acid and methyl jasmonate, over a range of dosages and screened for enhanced carotenoid production. Indole-3-acetic acid was the only hormone with an inductive effect on carotenoid accumulation. As such, the transcriptome under the condition with the highest carotenoid increase was profiled using RNA-Seq and expressed sequences reconstructed with de novo assembly. This allowed for the profiling of transcriptome-wide changes following auxin treatment, revealing the active pathway components of auxininduced carotenogenesis. Data analysis specified the differentially expressed genes involved in auxin biosynthesis and signal transduction, which suggest a close relationship to equivalent pathways in higher plants. However unlike in plants, the ancient ABP1/SCFSKP2A/IBR5-mediated pathways for auxin response likely acted as the primary signaling route in Chlorella. As carotenoids are precursors for abscisic acid, the findings suggest a causative link between auxin signaling and abiotic stress tolerance.HighlightTranscriptomics of plant hormone-treated Chlorella revealed the active pathway components of auxin-induced carotenogenesis and included the ancient ABP1/SCFSKP2A/IBR5-mediated pathways. The manuscript presents the first documented transcriptomic data of auxin-treated microalgae.

scholarly journals Using targeted re-sequencing for identification of candidate genes and SNPs for a QTL affecting the pH value of chicken muscle

2015 ◽  
Author(s):  
Xidan Li ◽  
Xiaodong Liu ◽  
Javad Nadaf ◽  
Elisabeth Le Bihan-Duval ◽  
Cécile Berri ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Ph Value ◽  
Sequence Data ◽  
Chromosome 1 ◽  
Chicken Breast ◽  
Candidate Snps ◽  
Post Mortem ◽  
Synonymous Snps ◽  
Chicken Muscle ◽  
Genetic Mechanisms

Using targeted genetical genomics, a QTL affecting the initial post-mortem pH value of chicken breast muscle (Pectoralis major) on chromosome 1 (GGA1) was recently fine-mapped. Thirteen genes were present in the QTL region of about 1 Mb. In this study, ten birds that were inferred to be homozygous for either the high (QQ) or low (qq) QTL allele were selected for re-sequencing. After enrichment for 1 Mb around the QTL region, > 200 x coverage for the QTL region in each of the ten birds was obtained. We used custom tools to identify putative causal mutations in the mapped QTL region from next generation sequence data. Four non-synonymous SNPs differentiating the two QTL genotype groups were identified within four local genes (PRDX4, EIF2S3, PCYT1B and E1BTD2). These were defined to be most likely candidate SNPs to explain the QTL effect. Moreover, 29 consensus SNPs were detected within gene-related regions (UTR regions and splicing sites) for the QQ birds and 26 for the qq birds. These could also play a role explaining the observed QTL effect. The results provide an important step for prioritizing among a large amount of candidate mutations and significantly contribute to the understanding of the genetic mechanisms affecting the initial post-mortem pH value of chicken muscle.

scholarly journals Rapid auxin-mediated phosphorylation of Myosin regulates trafficking and polarity in Arabidopsis

2021 ◽  
Author(s):  
Huibin Han ◽  
Inge Verstraeten ◽  
Mark Roosjen ◽  
Ewa Mazur ◽  
Nikola Rydza ◽  
...  
Keyword(s):  
Plant Development ◽  
Auxin Transport ◽  
Adaptor Protein ◽  
Feedback Regulation ◽  
Cellular Responses ◽  
Central Component ◽  
Auxin Signaling ◽  
Auxin Response ◽  
Cellular Processes ◽  
Myosin Xi

The signaling molecule auxin controls plant development through a well-known transcriptional mechanism that regulates many genes. However, auxin also triggers cellular responses within seconds or minutes, and mechanisms mediating such fast responses have remained elusive. Here, we identified an ultrafast auxin-mediated protein phosphorylation response in Arabidopsis roots that is largely independent of the canonical TIR1/AFB receptors. Among targets of this novel response are Myosin XI and its adaptor protein MadB2. We show that their auxin-mediated phosphorylation regulates trafficking and polar, subcellular distribution of PIN auxin transporters. This phosphorylation-based auxin signaling module is indispensable during developmental processes that rely on auxin-mediated PIN repolarization, such as termination of shoot gravitropic bending or vasculature formation and regeneration. Hence, we identified a fast, non-canonical auxin response targeting multiple cellular processes and revealed auxin-triggered phosphorylation of a myosin complex as the mechanism for feedback regulation of directional auxin transport, a central component of auxin canalization, which underlies self-organizing plant development.

scholarly journals Effects of Light Intensity on Root Development in a D-Root Growth System

2021 ◽  
Vol 12 ◽  
Author(s):  
Yohanna Evelyn Miotto ◽  
Cibele Tesser da Costa ◽  
Remko Offringa ◽  
Jürgen Kleine-Vehn ◽  
Felipe dos Santos Maraschin
Keyword(s):  
Light Intensity ◽  
Root Growth ◽  
Root Development ◽  
Light Exposure ◽  
Light Condition ◽  
Light Response ◽  
Shoot Elongation ◽  
Growth Conditions ◽  
Auxin Signaling ◽  
Loss Of Function

Plant development is highly affected by light quality, direction, and intensity. Under natural growth conditions, shoots are directly exposed to light whereas roots develop underground shielded from direct illumination. The photomorphogenic development strongly represses shoot elongation whereas promotes root growth. Over the years, several studies helped the elucidation of signaling elements that coordinate light perception and underlying developmental outputs. Light exposure of the shoots has diverse effects on main root growth and lateral root (LR) formation. In this study, we evaluated the phenotypic root responses of wild-type Arabidopsis plants, as well as several mutants, grown in a D-Root system. We observed that sucrose and light act synergistically to promote root growth and that sucrose alone cannot overcome the light requirement for root growth. We also have shown that roots respond to the light intensity applied to the shoot by changes in primary and LR development. Loss-of-function mutants for several root light-response genes display varying phenotypes according to the light intensity to which shoots are exposed. Low light intensity strongly impaired LR development for most genotypes. Only vid-27 and pils4 mutants showed higher LR density at 40 μmol m–2 s–1 than at 80 μmol m–2 s–1 whereas yuc3 and shy2-2 presented no LR development in any light condition, reinforcing the importance of auxin signaling in light-dependent root development. Our results support the use of D-Root systems to avoid the effects of direct root illumination that might lead to artifacts and unnatural phenotypic outputs.

scholarly journals Negative Feedback Regulation of Auxin Signaling by ATHB8/ACL5–BUD2 Transcription Module

2014 ◽  
Vol 7 (6) ◽  
pp. 1006-1025 ◽  
Author(s):  
Simona Baima ◽  
Valentina Forte ◽  
Marco Possenti ◽  
Andrés Peñalosa ◽  
Guido Leoni ◽  
...  
Keyword(s):  
Negative Feedback ◽  
Feedback Regulation ◽  
Auxin Signaling ◽  
Negative Feedback Regulation

scholarly journals Persistence of a Geographically-Stable Hybrid Zone in Puerto Rican Dwarf Geckos

2019 ◽  
Vol 110 (5) ◽  
pp. 523-534 ◽  
Author(s):  
Brendan J Pinto ◽  
James Titus-McQuillan ◽  
Juan D Daza ◽  
Tony Gamble
Keyword(s):  
Reproductive Isolation ◽  
Hybrid Zone ◽  
Sequence Data ◽  
Strong Support ◽  
Climatic Variables ◽  
Putative Hybrid ◽  
Hybrid Zones ◽  
Intermediate Phenotypes ◽  
Genetic Mechanisms ◽  
Stable Hybrid

Abstract Determining the mechanisms that create and maintain biodiversity is a central question in ecology and evolution. Speciation is the process that creates biodiversity. Speciation is mediated by incompatibilities that lead to reproductive isolation between divergent populations and these incompatibilities can be observed in hybrid zones. Gecko lizards are a speciose clade possessing an impressive diversity of behavioral and morphological traits. In geckos, however, our understanding of the speciation process is negligible. To address this gap, we used genetic sequence data (both mitochondrial and nuclear markers) to revisit a putative hybrid zone between Sphaerodactylus nicholsi and Sphaerodactylus townsendi in Puerto Rico, initially described in 1984. First, we addressed discrepancies in the literature on the validity of both species. Second, we sampled a 10-km-wide transect across the putative hybrid zone and tested explicit predictions about its dynamics using cline models. Third, we investigated potential causes for the hybrid zone using species distribution modeling and simulations; namely, whether unique climatic variables within the hybrid zone might elicit selection for intermediate phenotypes. We find strong support for the species-level status of each species and no evidence of movement, or unique climatic variables near the hybrid zone. We suggest that this narrow hybrid zone is geographically stable and is maintained by a combination of dispersal and selection. Thus, this work has identified an extant model system within geckos that that can be used for future investigations detailing genetic mechanisms of reproductive isolation in an understudied vertebrate group.

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