@article{gratz_organic_2021,
	title = {Organic nitrogen nutrition: {LHT1}.2 protein from hybrid aspen ({Populus} tremula {L}. x tremuloides {Michx}) is a functional amino acid transporter and a homolog of {Arabidopsis} {LHT1}},
	volume = {41},
	issn = {1758-4469},
	shorttitle = {Organic nitrogen nutrition},
	doi = {10.1093/treephys/tpab029},
	abstract = {The contribution of amino acids (AAs) to soil nitrogen (N) fluxes is higher than previously thought. The fact that AA uptake is pivotal for N nutrition in boreal ecosystems highlights plant AA transporters as key components of the N cycle. At the same time, very little is known about AA transport and respective transporters in trees. Tree genomes may contain 13 or more genes encoding the lysine histidine transporter (LHT) family proteins, and this complicates the study of their significance for tree N-use efficiency. With the strategy of obtaining a tool to study N-use efficiency, our aim was to identify and characterize a relevant AA transporter in hybrid aspen (Populus tremula L. x tremuloides Michx.). We identified PtrLHT1.2, the closest homolog of Arabidopsis thaliana (L.) Heynh AtLHT1, which is expressed in leaves, stems and roots. Complementation of a yeast AA uptake mutant verified the function of PtrLHT1.2 as an AA transporter. Furthermore, PtrLHT1.2 was able to fully complement the phenotypes of the Arabidopsis AA uptake mutant lht1 aap5, including early leaf senescence-like phenotype, reduced growth, decreased plant N levels and reduced root AA uptake. Amino acid uptake studies finally showed that PtrLHT1.2 is a high affinity transporter for neutral and acidic AAs. Thus, we identified a functional AtLHT1 homolog in hybrid aspen, which harbors the potential to enhance overall plant N levels and hence increase biomass production. This finding provides a valuable tool for N nutrition studies in trees and opens new avenues to optimizing tree N-use efficiency.},
	language = {eng},
	number = {8},
	journal = {Tree Physiology},
	author = {Gratz, Regina and Ahmad, Iftikhar and Svennerstam, Henrik and Jämtgård, Sandra and Love, Jonathan and Holmlund, Mattias and Ivanov, Rumen and Ganeteg, Ulrika},
	month = aug,
	year = {2021},
	pmid = {33631788},
	pmcid = {PMC8359683},
	keywords = {Amino Acid Transport Systems, Arabidopsis, Ecosystem, Nitrogen, Populus, Populus tremula L. x tremuloides Michx, amino acid transport, amino acid uptake, early senescence-like phenotype, hybrid aspen, lysine histidine transporter (LHT), nitrogen nutrition, organic nitrogen},
	pages = {1479--1496},
}

The contribution of amino acids (AAs) to soil nitrogen (N) fluxes is higher than previously thought. The fact that AA uptake is pivotal for N nutrition in boreal ecosystems highlights plant AA transporters as key components of the N cycle. At the same time, very little is known about AA transport and respective transporters in trees. Tree genomes may contain 13 or more genes encoding the lysine histidine transporter (LHT) family proteins, and this complicates the study of their significance for tree N-use efficiency. With the strategy of obtaining a tool to study N-use efficiency, our aim was to identify and characterize a relevant AA transporter in hybrid aspen (Populus tremula L. x tremuloides Michx.). We identified PtrLHT1.2, the closest homolog of Arabidopsis thaliana (L.) Heynh AtLHT1, which is expressed in leaves, stems and roots. Complementation of a yeast AA uptake mutant verified the function of PtrLHT1.2 as an AA transporter. Furthermore, PtrLHT1.2 was able to fully complement the phenotypes of the Arabidopsis AA uptake mutant lht1 aap5, including early leaf senescence-like phenotype, reduced growth, decreased plant N levels and reduced root AA uptake. Amino acid uptake studies finally showed that PtrLHT1.2 is a high affinity transporter for neutral and acidic AAs. Thus, we identified a functional AtLHT1 homolog in hybrid aspen, which harbors the potential to enhance overall plant N levels and hence increase biomass production. This finding provides a valuable tool for N nutrition studies in trees and opens new avenues to optimizing tree N-use efficiency.

@article{capador-barreto_killing_2021,
	title = {Killing two enemies with one stone? {Genomics} of resistance to two sympatric pathogens in {Norway} spruce},
	volume = {30},
	issn = {1365-294X},
	shorttitle = {Killing two enemies with one stone?},
	doi = {10.1111/mec.16058},
	abstract = {Trees must cope with the attack of multiple pathogens, often simultaneously during their long lifespan. Ironically, the genetic and molecular mechanisms controlling this process are poorly understood. The objective of this study was to compare the genetic component of resistance in Norway spruce to Heterobasidion annosum s.s. and its sympatric congener Heterobasidion parviporum. Heterobasidion root- and stem-rot is a major disease of Norway spruce caused by members of the Heterobasidion annosum species complex. Resistance to both pathogens was measured using artificial inoculations in half-sib families of Norway spruce trees originating from central to northern Europe. The genetic component of resistance was analysed using 63,760 genome-wide exome-capture sequenced SNPs and multitrait genome-wide associations. No correlation was found for resistance to the two pathogens; however, associations were found between genomic variants and resistance traits with synergic or antagonist pleiotropic effects to both pathogens. Additionally, a latitudinal cline in resistance in the bark to H. annosum s.s. was found; trees from southern latitudes, with a later bud-set and thicker stem diameter, allowed longer lesions, but this was not the case for H. parviporum. In summary, this study detects genomic variants with pleiotropic effects which explain multiple disease resistance from a genic level and could be useful for selection of resistant trees to both pathogens. Furthermore, it highlights the need for additional research to understand the evolution of resistance traits to multiple pathogens in trees.},
	language = {eng},
	number = {18},
	journal = {Molecular Ecology},
	author = {Capador-Barreto, Hernán D. and Bernhardsson, Carolina and Milesi, Pascal and Vos, Ingrid and Lundén, Karl and Wu, Harry X. and Karlsson, Bo and Ingvarsson, Pär K. and Stenlid, Jan and Elfstrand, Malin},
	month = sep,
	year = {2021},
	pmid = {34218489},
	keywords = {Basidiomycota, Genome wide association study (GWAS), Genomics, Homicide, Norway, Picea, Picea abies, Plant Diseases, cline, disease resistance, genome-wide association study, pleiotropy, root-rot},
	pages = {4433--4447},
}

Trees must cope with the attack of multiple pathogens, often simultaneously during their long lifespan. Ironically, the genetic and molecular mechanisms controlling this process are poorly understood. The objective of this study was to compare the genetic component of resistance in Norway spruce to Heterobasidion annosum s.s. and its sympatric congener Heterobasidion parviporum. Heterobasidion root- and stem-rot is a major disease of Norway spruce caused by members of the Heterobasidion annosum species complex. Resistance to both pathogens was measured using artificial inoculations in half-sib families of Norway spruce trees originating from central to northern Europe. The genetic component of resistance was analysed using 63,760 genome-wide exome-capture sequenced SNPs and multitrait genome-wide associations. No correlation was found for resistance to the two pathogens; however, associations were found between genomic variants and resistance traits with synergic or antagonist pleiotropic effects to both pathogens. Additionally, a latitudinal cline in resistance in the bark to H. annosum s.s. was found; trees from southern latitudes, with a later bud-set and thicker stem diameter, allowed longer lesions, but this was not the case for H. parviporum. In summary, this study detects genomic variants with pleiotropic effects which explain multiple disease resistance from a genic level and could be useful for selection of resistant trees to both pathogens. Furthermore, it highlights the need for additional research to understand the evolution of resistance traits to multiple pathogens in trees.

@article{velasquez_xyloglucan_2021,
	title = {Xyloglucan {Remodeling} {Defines} {Auxin}-{Dependent} {Differential} {Tissue} {Expansion} in {Plants}},
	volume = {22},
	issn = {1422-0067},
	doi = {10.3390/ijms22179222},
	abstract = {Size control is a fundamental question in biology, showing incremental complexity in plants, whose cells possess a rigid cell wall. The phytohormone auxin is a vital growth regulator with central importance for differential growth control. Our results indicate that auxin-reliant growth programs affect the molecular complexity of xyloglucans, the major type of cell wall hemicellulose in eudicots. Auxin-dependent induction and repression of growth coincide with reduced and enhanced molecular complexity of xyloglucans, respectively. In agreement with a proposed function in growth control, genetic interference with xyloglucan side decorations distinctly modulates auxin-dependent differential growth rates. Our work proposes that auxin-dependent growth programs have a spatially defined effect on xyloglucan's molecular structure, which in turn affects cell wall mechanics and specifies differential, gravitropic hypocotyl growth.},
	language = {eng},
	number = {17},
	journal = {International Journal of Molecular Sciences},
	author = {Velasquez, Silvia Melina and Guo, Xiaoyuan and Gallemi, Marçal and Aryal, Bibek and Venhuizen, Peter and Barbez, Elke and Dünser, Kai Alexander and Darino, Martin and Pĕnčík, Aleš and Novák, Ondřej and Kalyna, Maria and Mouille, Gregory and Benková, Eva and P Bhalerao, Rishikesh and Mravec, Jozef and Kleine-Vehn, Jürgen},
	month = aug,
	year = {2021},
	pmid = {34502129},
	pmcid = {PMC8430841},
	keywords = {Arabidopsis, Cell Wall, Fluorescent Antibody Technique, Gene Expression Regulation, Plant, Glucans, Indoleacetic Acids, Peas, Plant Cells, Plant Development, Plant Physiological Phenomena, Signal Transduction, Xylans, auxin, cell wall, gravitropism, growth, hypocotyls, xyloglucans},
	pages = {9222},
}

Size control is a fundamental question in biology, showing incremental complexity in plants, whose cells possess a rigid cell wall. The phytohormone auxin is a vital growth regulator with central importance for differential growth control. Our results indicate that auxin-reliant growth programs affect the molecular complexity of xyloglucans, the major type of cell wall hemicellulose in eudicots. Auxin-dependent induction and repression of growth coincide with reduced and enhanced molecular complexity of xyloglucans, respectively. In agreement with a proposed function in growth control, genetic interference with xyloglucan side decorations distinctly modulates auxin-dependent differential growth rates. Our work proposes that auxin-dependent growth programs have a spatially defined effect on xyloglucan's molecular structure, which in turn affects cell wall mechanics and specifies differential, gravitropic hypocotyl growth.

@article{singh_when_2021,
	title = {When to branch - seasonal control of shoot architecture in trees},
	issn = {1742-4658},
	doi = {10.1111/febs.16227},
	abstract = {Long-lived perennial plants optimize their shoot architecture by responding to seasonal cues. The main strategy used by the plants of temperate and boreal regions to survive the extremely unfavourable conditions of the winter is to protect their apical and lateral meristematic tissues. This involves myriads of transcriptional, translational and metabolic changes in the plants, as shoot architecture is controlled by multiple pathways that regulate processes such as bud formation and flowering, small RNAs, environmental factors (especially light quality, photoperiod and temperature), hormones, and sugars. Recent studies have begun to reveal how these pathways are recruited for the seasonal adaptation and regulation of shoot architecture in perennial plants, including the role of a regulatory module consisting of antagonistic players TERMINAL FLOWER1 (TFL1) and LIKE-AP1 (LAP1) in the hybrid aspen. Here, we review recent progress in understanding genetic controls of shoot architecture in perennials and compare them to those in annuals.},
	language = {eng},
	journal = {The FEBS journal},
	author = {Singh, Rajesh Kumar and Bhalerao, Rishikesh P. and Maurya, Jay P.},
	month = oct,
	year = {2021},
	pmid = {34652884},
	keywords = {Axillary buds, Branching, Photoperiod, Seasonal growth, Shoot Architecture, temperature},
}

Long-lived perennial plants optimize their shoot architecture by responding to seasonal cues. The main strategy used by the plants of temperate and boreal regions to survive the extremely unfavourable conditions of the winter is to protect their apical and lateral meristematic tissues. This involves myriads of transcriptional, translational and metabolic changes in the plants, as shoot architecture is controlled by multiple pathways that regulate processes such as bud formation and flowering, small RNAs, environmental factors (especially light quality, photoperiod and temperature), hormones, and sugars. Recent studies have begun to reveal how these pathways are recruited for the seasonal adaptation and regulation of shoot architecture in perennial plants, including the role of a regulatory module consisting of antagonistic players TERMINAL FLOWER1 (TFL1) and LIKE-AP1 (LAP1) in the hybrid aspen. Here, we review recent progress in understanding genetic controls of shoot architecture in perennials and compare them to those in annuals.

@article{zuch_cell_2021,
	title = {Cell biology of the leaf epidermis: {Fate} specification, morphogenesis and coordination},
	issn = {1040-4651},
	shorttitle = {Cell biology of the leaf epidermis},
	url = {https://doi.org/10.1093/plcell/koab250},
	doi = {10.1093/plcell/koab250},
	abstract = {As the outermost layer of plants, the epidermis serves as a critical interface between plants and the environment. During leaf development, the differentiation of specialized epidermal cell types, including stomatal guard cells, pavement cells and trichomes, occurs simultaneously, each providing unique and pivotal functions for plant growth and survival. Decades of molecular-genetic and physiological studies have unraveled key players and hormone signaling specifying epidermal differentiation. However, most studies focus on only one cell type at a time, and how these distinct cell types coordinate as a unit is far from well-comprehended. Here we provide a review on the current knowledge of regulatory mechanisms underpinning the fate specification, differentiation, morphogenesis, and positioning of these specialized cell types. Emphasis is given to their shared developmental origins, fate flexibility, as well as cell cycle and hormonal controls. Furthermore, we discuss computational modeling approaches to integrate how mechanical properties of individual epidermal cell types and entire tissue/organ properties mutually influence each other. We hope to illuminate the underlying mechanisms coordinating the cell differentiation that ultimately generate a functional leaf epidermis.},
	number = {koab250},
	urldate = {2021-10-15},
	journal = {The Plant Cell},
	author = {Zuch, Daniel T and Doyle, Siamsa M and Majda, Mateusz and Smith, Richard S and Robert, Stéphanie and Torii, Keiko U},
	month = oct,
	year = {2021},
}

As the outermost layer of plants, the epidermis serves as a critical interface between plants and the environment. During leaf development, the differentiation of specialized epidermal cell types, including stomatal guard cells, pavement cells and trichomes, occurs simultaneously, each providing unique and pivotal functions for plant growth and survival. Decades of molecular-genetic and physiological studies have unraveled key players and hormone signaling specifying epidermal differentiation. However, most studies focus on only one cell type at a time, and how these distinct cell types coordinate as a unit is far from well-comprehended. Here we provide a review on the current knowledge of regulatory mechanisms underpinning the fate specification, differentiation, morphogenesis, and positioning of these specialized cell types. Emphasis is given to their shared developmental origins, fate flexibility, as well as cell cycle and hormonal controls. Furthermore, we discuss computational modeling approaches to integrate how mechanical properties of individual epidermal cell types and entire tissue/organ properties mutually influence each other. We hope to illuminate the underlying mechanisms coordinating the cell differentiation that ultimately generate a functional leaf epidermis.