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1. Upper Crustal Structure and Magmatism in Southwest Washington: V p , V s , and V p / V s Results From the iMUSH Active‐Source Seismic Experiment

   https://doi.org/10.1029/2018JB016203  

   Kiser, E. ; Levander, A. ; Zelt, C. ; Schmandt, B. ; Hansen, S. ( July 2019 , Journal of Geophysical Research: Solid Earth)

   Structural details of the crust play an important role in controlling the distribution of volcanic activity in arc systems. In southwest Washington, several different regional structures associated with accretion and magmatism have been invoked to explain the broad distribution of Cascade volcanism in this region. In order to image these regional structures in the upper crust, Pg and Sg travel times from the imaging Magma Under St. Helens (iMUSH) active‐source seismic experiment are inverted forV_p,V_s, andV_p/V_smodels in the region surrounding Mount St. Helens. Several features of these models provide new insights into the regional structure of the upper crust. A large section of the Southern Washington Cascades Conductor is imaged as a lowV_p/V_sanomaly that is inferred to represent a broad sedimentary/metasedimentary sequence that composes the upper crust in this region. The accreted terrane Siletzia is imaged west of Mount St. Helens as north/south trending highV_pandV_p/V_sbodies. TheV_p/V_smodel shows relatively highV_p/V_sregions near Mount St. Helens and the Indian Heaven Volcanic Field, which could be related to the presence of magmatic fluids. Separating these two volcanic regions below 6‐km depth is a northeast trending series of highV_pandV_sbodies. These bodies have the same orientation as several volcanic/magmatic features at the surface, including Mount St. Helens and Mount Rainier, and it is argued that these high‐velocity features are a regional‐scale group of intrusive bodies associated with a crustal weak zone that focuses magma ascent.

    

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2. Paludicola gen. nov. and Revision of the Species Formerly in Batrachospermum Section  Turfosa (Batrachospermales, Rhodophyta)

   https://doi.org/10.1111/jpy.13001  

   Vis, Morgan L. ; Lee, Janina ; Eloranta, Pertti ; Chapuis, Iara S. ; Lam, Daryl W. ; Necchi, Jr., Orlando ; Oliveira, ed., M. C. ( May 2020 , Journal of Phycology)

   Since the first phylogenetic study of the order Batrachospermales,Batrachospermumwas shown to be paraphyletic. Subsequently, sections of the genus have been methodically investigated usingDNAsequences and morphology in order to propose new genera and delineate species.BatrachospermumsectionTurfosais the last section with multiple species yet to be examined. New sequence data of specimens from Europe and the United States were combined with the sparse sequence data already available. Phylogenetic analyses usingrbcL andCOI‐5P sequences showed this section to be a well‐supported clade, distinct fromBatrachospermumsectionBatrachospermumand its segregate genera. Section Turfosais raised to the generic rank asPaludicolagen. nov. Substantial genetic variation within the genus was discovered and 12 species are recognized based onDNAsequence data as well as morphological characters and geographic distribution. The following morphological characters were applied to distinguish species: branching pattern (pseudodichotomous or irregular), whorl size (reduced or well developed), primary fascicles (curved or straight), spermatangia origin (primary or secondary fascicles), and carposporophyte arrangement (loose or dense). Previously published species were transferred to the new genus:P. turfosa,P. keratophyta,P. orthosticha,P. phangiae,andP. periploca. Seven new species are proposed as follows:P. groenbladiifrom Europe;P. communis,P. johnhallii, andP. leafensisfrom North America; andP. aquanigra,P. diamantinensis, andP. turfosiformisfrom Brazil. In addition, three unsequenced species in the section,P. bakarensis,P. gombakensis, andP. tapirensis, were transferred to the new genus.

    

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3. R2R3‐MYB genes control petal pigmentation patterning in Clarkia gracilis ssp. sonomensis (Onagraceae)

   https://doi.org/10.1111/nph.16908  

   Lin, Rong‐Chien ; Rausher, Mark D. ( September 2020 , New Phytologist)

   Petal pigmentation patterning is widespread in flowering plants. The genetics of these pattern elements has been of great interest for understanding the evolution of phenotypic diversification. Here, we investigate the genetic changes responsible for the evolution of an unpigmented petal element on a colored background.

   We used transcriptome analysis, gene expression assays, cosegregation in F₂plants and functional tests to identify the gene(s) involved in petal coloration inClarkia gracilisssp.sonomensis.

   We identified an R2R3‐MYB transcription factor (CgsMYB12) responsible for anthocyanin pigmentation of the basal region (‘cup’) in the petal ofC.gracilisssp.sonomensis. A functional mutation inCgsMYB12creates a white cup on a pink petal background. Additionally, we found that twoR2R3‐MYBgenes (CgsMYB6andCgsMYB11) are also involved in petal background pigmentation. Each of these threeR2R3‐MYBgenes exhibits a different spatiotemporal expression pattern. The functionality of theseR2R3‐MYBgenes was confirmed through stable transformation ofArabidopsis.

   Distinct spatial patterns ofR2R3‐MYBexpression have created the possibility that pigmentation in different sections of the petal can evolve independently. This finding suggests that recent gene duplication has been central to the evolution of petal pigmentation patterning inC. gracilisssp.sonomensis.

    

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4. Alternating oligo( o , p -phenylenes) via ruthenium catalyzed diol–diene benzannulation: orthogonality to cross-coupling enables de novo nanographene and PAH construction

   https://doi.org/10.1039/C8SC03236J  

   Kasun, Zachary A. ; Sato, Hiroki ; Nie, Jing ; Mori, Yasuyuki ; Bender, Jon A. ; Roberts, Sean T. ; Krische, Michael J. ( January 2018 , Chemical Science)

   Ruthenium(0) catalyzed diol–diene benzannulation enables formation ofp-bromo-terminated alternating oligo(o,p-phenylenes) and, therefrom, diverse PAH materials.

    

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5. Lateral Leaflet Suppression 1 ( LLS1 ), encoding the MtYUCCA1 protein, regulates lateral leaflet development in Medicago truncatula

   https://doi.org/10.1111/nph.16539  

   Zhao, Baolin ; He, Liangliang ; Jiang, Chuan ; Liu, Ye ; He, Hua ; Bai, Quanzi ; Zhou, Shaoli ; Zheng, Xiaoling ; Wen, Jiangqi ; Mysore, Kirankumar S. ; et al ( April 2020 , New Phytologist)

   In species with compound leaves, the positions of leaflet primordium initiation are associated with local peaks of auxin accumulation. However, the role of auxin during the late developmental stages and outgrowth of compound leaves remains largely unknown.

   Using genome resequencing approaches, we identified insertion sites at four alleles of theLATERAL LEAFLET SUPPRESSION1(LLS1) gene, encoding the auxin biosynthetic enzyme YUCCA1 inMedicago truncatula.

   Linkage analysis and complementation tests showed that thells1mutant phenotypes were caused by theTnt1insertions that disrupted theLLS1gene. The transcripts ofLLS1can be detected in primordia at early stages of leaf initiation and later in the basal regions of leaflets, and finally in vein tissues at late leaf developmental stages. Vein numbers and auxin content are reduced in thells1‐1mutant. Analysis of thells1 sgl1andlls1 palm1double mutants revealed thatSGL1is epistatic toLLS1, andLLS1works withPALM1in an independent pathway to regulate the growth of lateral leaflets.

   Our work demonstrates that the YUCCA1/YUCCA4 subgroup plays very important roles in the outgrowth of lateral leaflets during compound leaf development ofM. truncatula, in addition to leaf venation.

    

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