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Bruno Guillotin, Mohammad Etemadi, Corinne Audran, Mondher Bouzayen, Guillaume Bécard, Jean-Philippe Combier
Root colonization by arbuscular mycorrhizal (AM) fungi is a complex and finely tuned process. Previous studies have shown that, among other plant hormones, auxin plays a role in this process but the specific involvement of Aux/IAAs, the key regulators of auxin responses, is still unknown. In this study, we addressed the role of the tomato Sl-IAA27 during AM symbiosis by using Sl-IAA27-RNAi and pSL-IAA27::GUS stable tomato lines. The data show that Sl-IAA27 expression is up-regulated by the AM fungus and that silencing of Sl-IAA27 has a negative impact on AM colonization...
October 17, 2016: New Phytologist
Philip B Brewer, Kaori Yoneyama, Fiona Filardo, Emma Meyers, Adrian Scaffidi, Tancred Frickey, Kohki Akiyama, Yoshiya Seto, Elizabeth A Dun, Julia E Cremer, Stephanie C Kerr, Mark T Waters, Gavin R Flematti, Michael G Mason, Georg Weiller, Shinjiro Yamaguchi, Takahito Nomura, Steven M Smith, Koichi Yoneyama, Christine A Beveridge
Strigolactones are a group of plant compounds of diverse but related chemical structures. They have similar bioactivity across a broad range of plant species, act to optimize plant growth and development, and promote soil microbe interactions. Carlactone, a common precursor to strigolactones, is produced by conserved enzymes found in a number of diverse species. Versions of the MORE AXILLARY GROWTH1 (MAX1) cytochrome P450 from rice and Arabidopsis thaliana make specific subsets of strigolactones from carlactone...
May 31, 2016: Proceedings of the National Academy of Sciences of the United States of America
Gavin R Flematti, Adrian Scaffidi, Mark T Waters, Steven M Smith
Plants produce strigolactones with different structures and different stereospecificities which provides the potential for diversity and flexibility of function. Strigolactones (SLs) typically comprise a tricyclic ABC ring system linked through an enol-ether bridge to a butenolide D-ring. The stereochemistry of the butenolide ring is conserved but two alternative configurations of the B-C ring junction leads to two families of SLs, exemplified by strigol and orobanchol. Further modifications lead to production of many different strigolactones within each family...
June 2016: Planta
Mark Bruno, Salim Al-Babili
The β-carotene isomerase OsDWARF27 is stereo- and double bond-specific. It converts bicyclic carotenoids with at least one unsubstituted β-ionone ring. OsDWARF27 may contribute to the formation of α-carotene-based strigolactone-like compounds. Strigolactones (SLs) are synthesized from all-trans-β-carotene via a pathway involving the β-carotene isomerase DWARF27, the carotenoid cleavage dioxygenases 7 and 8 (CCD7, CCD8), and cytochrome P450 enzymes from the 711 clade (MAX1 in Arabidopsis). The rice enzyme DWARF27 was shown to catalyze the reversible isomerization of all-trans- into 9-cis-β-carotene in vitro...
June 2016: Planta
Shinsaku Ito, Ken Ito, Naoko Abeta, Ryo Takahashi, Yasuyuki Sasaki, Shunsuke Yajima
Strigolactones (SLs) are a group of terpenoid lactones found in plants that regulate diverse developmental phenomena. SLs are thought to be involved in the maintenance of phosphate homeostasis. In addition, SL signaling is required for the regulation of shoot branching by nitrogen supply in Arabidopsis. In this study, we evaluated the effects of SLs on nitrogen deficient-inducing phenomena (leaf senescence and reduction of plant weight) in Arabidopsis. SL-biosynthesis (max1-1) and SL-insensitive (atd14-1) mutants showed altered responses to nitrogen deficient in comparison with wild-type (WT) plants...
2016: Plant Signaling & Behavior
Päivi L H Rinne, Laju K Paul, Jorma Vahala, Raili Ruonala, Jaakko Kangasjärvi, Christiaan van der Schoot
Tree architecture develops over time through the collective activity of apical and axillary meristems. Although the capacity of both meristems to form buds is crucial for perennial life, a comparative analysis is lacking. As shown here for hybrid aspen, axillary meristems engage in an elaborate process of axillary bud (AXB) formation, while apical dominance prevents outgrowth of branches. Development ceased when AXBs had formed an embryonic shoot (ES) with a predictable number of embryonic leaves at the bud maturation point (BMP)...
November 2015: Journal of Experimental Botany
Katelyn Nagy-Smith, Eric Moore, Joel Schneider, Robert Tycko
Most, if not all, peptide- and protein-based hydrogels formed by self-assembly can be characterized as kinetically trapped 3D networks of fibrils. The propensity of disease-associated amyloid-forming peptides and proteins to assemble into polymorphic fibrils suggests that cross-β fibrils comprising hydrogels may also be polymorphic. We use solid-state NMR to determine the molecular and supramolecular structure of MAX1, a de novo designed gel-forming peptide, in its fibrillar state. We find that MAX1 adopts a β-hairpin conformation and self-assembles with high fidelity into a double-layered cross-β structure...
August 11, 2015: Proceedings of the National Academy of Sciences of the United States of America
Elisabeth Stes, Stephen Depuydt, Annick De Keyser, Cedrick Matthys, Kris Audenaert, Koichi Yoneyama, Stefaan Werbrouck, Sofie Goormachtig, Danny Vereecke
Leafy gall syndrome is the consequence of modified plant development in response to a mixture of cytokinins secreted by the biotrophic actinomycete Rhodococcus fascians. The similarity of the induced symptoms with the phenotype of plant mutants defective in strigolactone biosynthesis and signalling prompted an evaluation of the involvement of strigolactones in this pathology. All tested strigolactone-related Arabidopsis thaliana mutants were hypersensitive to R. fascians. Moreover, treatment with the synthetic strigolactone mixture GR24 and with the carotenoid cleavage dioxygenase inhibitor D2 illustrated that strigolactones acted as antagonistic compounds that restricted the morphogenic activity of R...
August 2015: Journal of Experimental Botany
Salim Al-Babili, Harro J Bouwmeester
Strigolactones (SLs) are carotenoid-derived plant hormones and signaling molecules. When released into the soil, SLs indicate the presence of a host to symbiotic fungi and root parasitic plants. In planta, they regulate several developmental processes that adapt plant architecture to nutrient availability. Highly branched/tillered mutants in Arabidopsis, pea, and rice have enabled the identification of four SL biosynthetic enzymes: a cis/trans-carotene isomerase, two carotenoid cleavage dioxygenases, and a cytochrome P450 (MAX1)...
2015: Annual Review of Plant Biology
Yifat Miller, Buyong Ma, Ruth Nussinov
Hydrogels are proving to be an excellent class of materials for biomedical applications. The molecular self-assembly of designed MAX1 β-hairpin peptides into fibrillar networks has emerged as a novel route to form responsive hydrogels. Herein, computational modeling techniques are used to investigate the relative arrangements of individual hairpins within the fibrils that constitute the gel. The modeling provides insight into the morphology of the fibril network, which defines the gel's mechanical properties...
January 15, 2015: Journal of Physical Chemistry. B
Satoko Abe, Aika Sado, Kai Tanaka, Takaya Kisugi, Kei Asami, Saeko Ota, Hyun Il Kim, Kaori Yoneyama, Xiaonan Xie, Toshiyuki Ohnishi, Yoshiya Seto, Shinjiro Yamaguchi, Kohki Akiyama, Koichi Yoneyama, Takahito Nomura
Strigolactones (SLs) stimulate seed germination of root parasitic plants and induce hyphal branching of arbuscular mycorrhizal fungi in the rhizosphere. In addition, they have been classified as a new group of plant hormones essential for shoot branching inhibition. It has been demonstrated thus far that SLs are derived from carotenoid via a biosynthetic precursor carlactone (CL), which is produced by sequential reactions of DWARF27 (D27) enzyme and two carotenoid cleavage dioxygenases CCD7 and CCD8. We previously found an extreme accumulation of CL in the more axillary growth1 (max1) mutant of Arabidopsis, which exhibits increased lateral inflorescences due to SL deficiency, indicating that CL is a probable substrate for MAX1 (CYP711A1), a cytochrome P450 monooxygenase...
December 16, 2014: Proceedings of the National Academy of Sciences of the United States of America
Benjun Zhou
Kinetics of chromium (VI) reduction and phenol biodegradation by a pure culture of Pseudomonas sp. JF122 was studied. High inoculum (volume) increased both chromium (VI) reduction and phenol biodegradation velocity, which are ascribable to shorter acclimation period requirement for cell growth. Haldane's kinetics model adequately described the substrate kinetics with kinetic constants μ(max1) =0.113 h⁻¹, K(s1) = 0.4009 mM, K(i1) =5.165 mM for chromium (VI) reduction and μ(max2) =0.3081 h⁻¹, K(s2) =7...
November 2014: Pakistan Journal of Pharmaceutical Sciences
Yanxia Zhang, Aalt D J van Dijk, Adrian Scaffidi, Gavin R Flematti, Manuel Hofmann, Tatsiana Charnikhova, Francel Verstappen, Jo Hepworth, Sander van der Krol, Ottoline Leyser, Steven M Smith, Binne Zwanenburg, Salim Al-Babili, Carolien Ruyter-Spira, Harro J Bouwmeester
Strigolactones (SLs) are a class of phytohormones and rhizosphere signaling compounds with high structural diversity. Three enzymes, carotenoid isomerase DWARF27 and carotenoid cleavage dioxygenases CCD7 and CCD8, were previously shown to convert all-trans-β-carotene to carlactone (CL), the SL precursor. However, how CL is metabolized to SLs has remained elusive. Here, by reconstituting the SL biosynthetic pathway in Nicotiana benthamiana, we show that a rice homolog of Arabidopsis More Axillary Growth 1 (MAX1), encodes a cytochrome P450 CYP711 subfamily member that acts as a CL oxidase to stereoselectively convert CL into ent-2'-epi-5-deoxystrigol (B-C lactone ring formation), the presumed precursor of rice SLs...
December 2014: Nature Chemical Biology
Sameer Sathaye, Huixi Zhang, Cem Sonmez, Joel P Schneider, Christopher M MacDermaid, Christopher D Von Bargen, Jeffery G Saven, Darrin J Pochan
The MAX1 β-hairpin peptide (VKVKVKVK-V(D)PPT-KVKVKVKV-NH2) has been shown to form nanofibrils having a cross-section of two folded peptides forming a hydrophobic, valine-rich core, and the polymerized fibril exhibits primarily β-sheet hydrogen bonding.1-7 These nanofibrils form hydrogel networks through fibril entanglements as well as fibril branching.8 Fibrillar branching in MAX1 hydrogel networks provide the ability to flow under applied shear stress and immediately reform a hydrogel solid on cessation of shear...
November 10, 2014: Biomacromolecules
Ignacio Martin-Arjol, Joan Llorens Llacuna, Angeles Manresa
We modelled the production of hydroxy fatty acids from oleic acid by Pseudomonas aeruginosa 42A2 in a bioreactor with a non-dispersive aeration system. First, we designed an adapted wetted-wall gas-absorption column, offering a k La value of 39.9 h(-1), to enhance oxygen absorption in the culture media and prevent foam formation. Then, we analysed different kinetic models to simulate the yield coefficients and the kinetic constants in this bacterial transformation. Monod model fitting (μ max1 = 0.51 h(-1), K S1 = 1...
December 2014: Applied Microbiology and Biotechnology
M M Alam, E S Mace, E J van Oosterom, A Cruickshank, C H Hunt, G L Hammer, D R Jordan
A QTL model for the genetic control of tillering in sorghum is proposed, presenting new opportunities for sorghum breeders to select germplasm with tillering characteristics appropriate for their target environments. Tillering in sorghum can be associated with either the carbon supply-demand (S/D) balance of the plant or an intrinsic propensity to tiller (PTT). Knowledge of the genetic control of tillering could assist breeders in selecting germplasm with tillering characteristics appropriate for their target environments...
October 2014: TAG. Theoretical and Applied Genetics. Theoretische und Angewandte Genetik
Ragnar Bjering, Kari Birkeland, Vaska Vandevska-Radunovic
OBJECTIVE: To assess orthodontic treatment outcome at debonding and at 3 and 5 years after orthodontic treatment and to investigate the influence of different retention protocols on anterior tooth alignment. MATERIALS AND METHODS: Using the Peer Assessment Rating (PAR) Index, 169 patients (74 boys, 95 girls) were analyzed at four stages: pretreatment (T0), posttreatment (T1), 3 years posttreatment (T3), and 5 years posttreatment (T5). The PAR anterior component scores (ACSs) were compared between groups with different retention protocols...
May 2015: Angle Orthodontist
Cuixia Chen, Yanfeng Gu, Li Deng, Shuyi Han, Xing Sun, Yucan Chen, Jian R Lu, Hai Xu
Self-assembling peptide hydrogels with faster gelation kinetics and higher mechanical rigidity are favorable for their practical applications. A design strategy to control the folding, self-assembly, and hydrogelation of β-hairpin peptides via hydrophobic amino acid substitutions has been explored in this study. Isoleucine has higher hydrophobicity and stronger propensity for β-sheet hydrogen bonding than valine. After the valine residues of MAX1 (VKVKVKVKV(D)PPTKVKVKVKV-NH2) were replaced with isoleucines, oscillatory rheometry and circular dichroism (CD) spectroscopy characterizations indicated that the variants had clearly faster self-assembly and hydrogelation rates and that the resulting gels displayed higher mechanical stiffness...
August 27, 2014: ACS Applied Materials & Interfaces
Olaf Czarnecki, Jun Yang, Xiaoping Wang, Shucai Wang, Wellington Muchero, Gerald A Tuskan, Jin-Gui Chen
BACKGROUND: Strigolactones are a new class of plant hormones that play a key role in regulating shoot branching. Studies of branching mutants in Arabidopsis, pea, rice and petunia have identified several key genes involved in strigolactone biosynthesis or signaling pathway. In the model plant Arabidopsis, MORE AXILLARY GROWTH1 (MAX1), MAX2, MAX3 and MAX4 are four founding members of strigolactone pathway genes. However, little is known about the strigolactone pathway genes in the woody perennial plants...
2014: PloS One
Catarina Cardoso, Yanxia Zhang, Muhammad Jamil, Jo Hepworth, Tatsiana Charnikhova, Stanley O N Dimkpa, Caroline Meharg, Mark H Wright, Junwei Liu, Xiangbing Meng, Yonghong Wang, Jiayang Li, Susan R McCouch, Ottoline Leyser, Adam H Price, Harro J Bouwmeester, Carolien Ruyter-Spira
Rice (Oryza sativa) cultivar Azucena--belonging to the Japonica subspecies--exudes high strigolactone (SL) levels and induces high germination of the root parasitic plant Striga hermonthica. Consistent with the fact that SLs also inhibit shoot branching, Azucena is a low-tillering variety. In contrast, Bala, an Indica cultivar, is a low-SL producer, stimulates less Striga germination, and is highly tillered. Using a Bala × Azucena F6 population, a major quantitative trait loci--qSLB1.1--for the exudation of SL, tillering, and induction of Striga germination was detected on chromosome 1...
February 11, 2014: Proceedings of the National Academy of Sciences of the United States of America
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