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 the Linkage analysis and complementation tests showed that the Our work demonstrates that the YUCCA1/YUCCA4 subgroup plays very important roles in the outgrowth of lateral leaflets during compound leaf development of
Patterned leaf coloration in plants generates remarkable diversity in nature, but the underlying mechanisms remain largely unclear. Here, using RH1 mainly functions as an anthocyanin biosynthesis activator that specifically determines leaf marking formation depending on its C‐terminal activation motif. RH1 physically interacts with the Our findings reveal the molecular mechanism of the antagonistic gene paralogs RH1 and RH2 in determining anthocyanin leaf markings in
- NSF-PAR ID:
- 10452584
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 229
- Issue:
- 6
- ISSN:
- 0028-646X
- Page Range / eLocation ID:
- p. 3330-3344
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Summary LATERAL LEAFLET SUPPRESSION1 (LLS1 ) gene, encoding the auxin biosynthetic enzyme YUCCA1 inMedicago truncatula .lls1 mutant phenotypes were caused by theTnt1 insertions that disrupted theLLS1 gene. The transcripts ofLLS1 can 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 thells1‐1 mutant. Analysis of thells1 sgl1 andlls1 palm1 double mutants revealed thatSGL1 is epistatic toLLS1 , andLLS1 works withPALM1 in an independent pathway to regulate the growth of lateral leaflets.M. truncatula , in addition to leaf venation. -
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Key points Association of plasma membrane BKCachannels with BK‐β subunits shapes their biophysical properties and physiological roles; however, functional modulation of the mitochondrial BKCachannel (mitoBKCa) by BK‐β subunits is not established.
MitoBKCa‐α and the regulatory BK‐β1 subunit associate in mouse cardiac mitochondria.
A large fraction of mitoBKCadisplay properties similar to that of plasma membrane BKCawhen associated with BK‐β1 (left‐shifted voltage dependence of activation,
V 1/2 = −55 mV, 12 µm matrix Ca2+).In BK‐β1 knockout mice, cardiac mitoBKCadisplayed a low
P oand a depolarizedV 1/2of activation (+47 mV at 12 µm matrix Ca2+)Co‐expression of BKCawith the BK‐β1 subunit in HeLa cells doubled the density of BKCain mitochondria.
The present study supports the view that the cardiac mitoBKCachannel is functionally modulated by the BK‐β1 subunit; proper targeting and activation of mitoBKCashapes mitochondrial Ca2+handling.
Abstract Association of the plasma membrane BKCachannel with auxiliary BK‐β1–4 subunits profoundly affects the regulatory mechanisms and physiological processes in which this channel participates. However, functional association of mitochondrial BK (mitoBKCa) with regulatory subunits is unknown. We report that mitoBKCafunctionally associates with its regulatory subunit BK‐β1 in adult rodent cardiomyocytes. Cardiac mitoBKCais a calcium‐ and voltage‐activated channel that is sensitive to paxilline with a large conductance for K+of 300 pS. Additionally, mitoBKCadisplays a high open probability (
P o) and voltage half‐activation (V 1/2 = −55 mV,n = 7) resembling that of plasma membrane BKCawhen associated with its regulatory BK‐β1 subunit. Immunochemistry assays demonstrated an interaction between mitochondrial BKCa‐α and its BK‐β1 subunit. Mitochondria from the BK‐β1 knockout (KO) mice showed sparse mitoBKCacurrents (five patches with mitoBKCaactivity out of 28 total patches fromn = 5 different hearts), displaying a depolarizedV 1/2of activation (+47 mV in 12 µm matrix Ca2+). The reduced activity of mitoBKCawas accompanied by a high expression of BKCatranscript in the BK‐β1 KO, suggesting a lower abundance of mitoBKCachannels in this genotype. Accordingly, BK‐β1subunit increased the localization of BKDEC (i.e. the splice variant of BKCathat specifically targets mitochondria) into mitochondria by two‐fold. Importantly, both paxilline‐treated and BK‐β1 KO mitochondria displayed a more rapid Ca2+overload, featuring an early opening of the mitochondrial transition pore. We provide strong evidence that mitoBKCaassociates with its regulatory BK‐β1 subunit in cardiac mitochondria, ensuring proper targeting and activation of the mitoBKCachannel that helps to maintain mitochondrial Ca2+homeostasis. -
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Abstract Anthocyanins and proanthocyanins (PAs) are two end products of the flavonoid biosynthesis pathway. They are believed to be synthesized in the endoplasmic reticulum and then sequestered into the vacuole. In Arabidopsis thaliana, TRANSPARENT TESTA 19 (TT19) is necessary for both anthocyanin and PA accumulation. Here, we found that MtGSTF7, a homolog of AtTT19, is essential for anthocyanin accumulation but not required for PA accumulation in Medicago truncatula. MtGSTF7 was induced by the anthocyanin regulator LEGUME ANTHOCYANIN PRODUCTION 1 (LAP1), and its tissue expression pattern correlated with anthocyanin deposition in M. truncatula. Tnt1-insertional mutants of MtGSTF7 lost anthocyanin accumulation in vegetative organs, and introducing a genomic fragment of MtGSTF7 could complement the mutant phenotypes. Additionally, the accumulation of anthocyanins induced by LAP1 was significantly reduced in mtgstf7 mutants. Yeast-one-hybridization and dual-luciferase reporter assays revealed that LAP1 could bind to the MtGSTF7 promoter to activate its expression. Ectopic expression of MtGSTF7 in tt19 mutants could rescue their anthocyanin deficiency, but not their PA defect. Furthermore, PA accumulation was not affected in the mtgstf7 mutants. Taken together, our results show that the mechanism of anthocyanin and PA accumulation in M. truncatula is different from that in A. thaliana, and provide a new target gene for engineering anthocyanins in plants.
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MtNCC1 is a nodule‐specific Cu+‐chaperone encoded in the
Medicago truncatula genome, with a N‐terminus Atx1‐like domain that can bind Cu+with picomolar affinities. MtNCC1 is able to interact with nodule‐specific Cu+‐importer MtCOPT1.MtNCC1 is expressed primarily from the late infection zone to the early fixation zone and is located in the cytosol, associated with plasma and symbiosome membranes, and within nuclei. Consistent with its key role in nitrogen fixation,ncc1 mutants have a severe reduction in nitrogenase activity and a 50% reduction in copper‐dependent cytochromec oxidase activity.A subset of the copper proteome is also affected in the
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Ferroportin family members in model legume
Medicago truncatula were identified and their expression was determined. Yeast complementation assays, immunolocalization, characterization of atnt1 insertional mutant line, and synchrotron‐based X‐ray fluorescence assays were carried out in the nodule‐specificM. truncatula ferroportinMedicago truncatula nodule‐specific geneFerroportin2 (MtFPN2 ) is an iron‐efflux protein. MtFPN2 is located in intracellular membranes in the nodule vasculature and in inner nodule tissues, as well as in the symbiosome membranes in the interzone and early‐fixation zone of the nodules. Loss‐of‐function ofMtFPN2 alters iron distribution and speciation in nodules, reducing nitrogenase activity and biomass production. Using promoters with different tissular activity to driveMtFPN2 expression inMtFPN2 mutants, we determined that expression in the inner nodule tissues is sufficient to restore the phenotype, while confiningMtFPN2 expression to the vasculature did not improve the mutant phenotype.These data indicate that MtFPN2 plays a primary role in iron delivery to nitrogen‐fixing bacteroids in
M. truncatula nodules.
