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Cryptochromes (CRYs) are photoreceptors or components of the molecular clock in various evolutionary lineages, and they are commonly regulated by polyubiquitination and proteolysis. Multiple E3 ubiquitin ligases regulate CRYs in animal models, and previous genetics study also suggest existence of multiple E3 ubiquitin ligases for plant CRYs. However, only one E3 ligase, Cul4 COP1/SPAs , has been reported for plant CRYs so far. Here we show that Cul3 LRBs is the second E3 ligase of CRY2 in Arabidopsis . We demonstrate the blue light-specific and CRY-dependent activity of LRBs (Light-Response Bric-a-Brack/Tramtrack/Broad 1, 2 & 3) in blue-light regulation of hypocotyl elongation. LRBs physically interact with photoexcited and phosphorylated CRY2, at the CCE domain of CRY2, to facilitate polyubiquitination and degradation of CRY2 in response to blue light. We propose that Cul4 COP1/SPAs and Cul3 LRBs E3 ligases interact with CRY2 via different structure elements to regulate the abundance of CRY2 photoreceptor under different light conditions, facilitating optimal photoresponses of plants grown in nature. The fate of proteins in cells is determined by not only synthesis but also degradation. Here Chen et al. show that degradation of the plant blue light receptor CRY2 is determined by two distinct E3 ubiquitin ligases, Cul4 COP1/SPAs and Cul3 LRBs , regulating the function of CRY2 under different light conditions.

Plant organ growth and final shape rely on cell proliferation and, particularly, on cell expansion that largely determines the visible growth of plant organs. Arabidopsis (Arabidopsis thaliana) petals serve as an excellent model for dissecting the coordinated regulation of patterns of cell expansion and organ growth, but the molecular signaling mechanisms underlying this regulation remain largely unknown. Here, we demonstrate that during the late petal development stages, SPIKE1 (SPK1), encoding a guanine nucleotide exchange factor, activates Rho of Plants (ROP) GTPase proteins (ROP2, ROP4, and ROP6) to affect anisotropic expansion of epidermal cells in both petal blades and claws, thereby affecting anisotropic growth of the petal and the final characteristic organ shape. The petals of SPK1 knockdown mutants were significantly longer but narrower than those of the wild type, associated with increased anisotropic expansion of epidermal cells at late development stages. In addition, ROP2, ROP4, and ROP6 are activated by SPK1 to promote the isotropic organization of cortical microtubule arrays and thus inhibit anisotropic growth in the petal. Both knockdown of SPK1 and multiple rop mutants caused highly ordered cortical microtubule arrays that were transversely oriented relative to the axis of cell elongation after development stage 11. Taken together, our results suggest a SPK1-ROP-dependent signaling module that influences anisotropic growth in the petal and defines the final organ shape.

Cell polarization via asymmetrical distribution of structures or molecules is essential for diverse cellular functions and development of organisms, but how polarity is developmentally controlled has been poorly understood. In plants, the asymmetrical distribution of the PIN-FORMED (PIN) proteins involved in the cellular efflux of the quintessential phytohormone auxin plays a central role in developmental patterning, morphogenesis, and differential growth. Recently we showed that auxin promotes cell interdigitation by activating the Rho family ROP GTPases in leaf epidermal pavement cells. Here we found that auxin activation of the ROP2 signaling pathway regulates the asymmetric distribution of PIN1 by inhibiting its endocytosis. ROP2 inhibits PIN1 endocytosis via the accumulation of cortical actin microfilaments induced by the ROP2 effector protein RIC4. Our findings suggest a link between the developmental auxin signal and polar PIN1 distribution via Rho-dependent cytoskeletal reorganization and reveal the conservation of a design principle for cell polarization that is based on Rho GTPase-mediated inhibition of endocytosis.

Petal Growth Mediated by the Cell Proliferation to Expansion Transition The growth of petal primordia in the second whorl occurs through two waves:early stage cell division and late stage post-mitotic expansion (Huang and Irish,2016). Regulation of Petal Cell Maturation Following the transition from cell division to expansion, another critical factor that controls petal growth is the degree of expansion and final cell shape.Zhang and Zhangshow that genome size of Paphiopedilum (Orchidaceae) species is negatively correlated with labellum epidermal cell size, and positively correlated with the size of leaf epidermal cells, which suggests that genome size may be a strong predictor of cell size. [...]Cavallini-Speisser et al.write a review to summarize the major cell types in the petal and their functions. Relationship Between Petal Development and Pollination Variation in petal development that results in the diversity of petal morphologies has important implications in attracting specific pollinators for different plant species (Fenster et al.,2004; Stuurman et al.,2004).

The physiological functions of epidermal cells are largely determined by their diverse morphologies. Most flowering plants have special conical-shaped petal epidermal cells that are thought to influence light capture and reflectance, and provide pollinator grips, but the molecular mechanisms controlling conical cell shape remain largely unknown. Here, we developed a live-confocal imaging approach to quantify geometric parameters of conical cells in Arabidopsis thaliana (A. thaliana). Through genetic screens, we identified katanin (KTN1) mutants showing a phenotype of decreased tip sharpening of conical cells. Furthermore, we demonstrated that SPIKE1 and Rho of Plants (ROP) GTPases were required for the final shape formation of conical cells, as KTN1 does. Live-cell imaging showed that wild-type cells exhibited random orientation of cortical microtubule arrays at early developmental stages but displayed a well-ordered circumferential orientation of microtubule arrays at later stages. By contrast, loss of KTN1 prevented random microtubule networks from shifting into well-ordered arrays. We further showed that the filamentous actin cap, which is a typical feature of several plant epidermal cell types including root hairs and leaf trichomes, was not observed in the growth apexes of conical cells during cell development. Moreover, our genetic and pharmacological data suggested that microtubules but not actin are required for conical cell shaping. Together, our results provide a novel imaging approach for studying petal conical cell morphogenesis and suggest that the spatio-temporal organization of microtubule arrays plays crucial roles in controlling conical cell shape.

Plants have evolved diverse cell types with distinct sizes, shapes, and functions. For example, most flowering plants contain specialized petal conical epidermal cells that are thought to attract pollinators and influence light capture and reflectance, but the molecular mechanisms controlling conical cell shaping remain unclear. Here, through a genetic screen in Arabidopsis thaliana, we demonstrated that loss-of-function mutations in ANGUSTIFOLIA (AN), which encodes for a homolog of mammalian CtBP/BARs, displayed conical cells phenotype with wider tip angles, correlating with increased accumulation of reactive oxygen species (ROS). We further showed that exogenously supplied ROS generated similar conical cell phenotypes as the an mutants. Moreover, reduced endogenous ROS levels resulted in deceased tip sharpening of conical cells. Furthermore, through enhancer screening, we demonstrated that mutations in katanin (KTN1) enhanced conical cell phenotypes of the an-t1 mutants. Genetic analyses showed that AN acted in parallel with KTN1 to control conical cell shaping. Both increased or decreased ROS levels and mutations in AN suppressed microtubule organization into well-ordered circumferential arrays. We demonstrated that the AN-ROS pathway jointly functioned with KTN1 to modulate microtubule ordering, correlating with the tip sharpening of conical cells. Collectively, our findings revealed a mechanistic insight into ROS homeostasis regulation of microtubule organization and conical cell shaping.

Proper flower development is essential for sexual reproductive success and the setting of fruits and seeds. The availability of a high quality genome sequence for pineapple makes it an excellent model for studying fruit and floral organ development. In this study, we sequenced 27 different pineapple floral samples and integrated nine published RNA-seq datasets to generate tissue- and stage-specific transcriptomic profiles. Pairwise comparisons and weighted gene co-expression network analysis successfully identified ovule-, stamen-, petal- and fruit-specific modules as well as hub genes involved in ovule, fruit and petal development. In situ hybridization confirmed the enriched expression of six genes in developing ovules and stamens. Mutant characterization and complementation analysis revealed the important role of the subtilase gene AcSBT1.8 in petal development. This work provides an important genomic resource for functional analysis of pineapple floral organ growth and fruit development and sheds light on molecular networks underlying pineapple reproductive organ growth. Wang et al. perform RNA-Seq on pineapple floral samples and also use previously published RNA-Seq datasets to generate tissue- and stage-specific transcriptomic profiles. The authors use weighted gene co-expression network analysis to identify gene networks, bringing insight to underlying pineapple reproductive organ growth.

Within a multicellular tissue cells may coordinately form a singular or multiple polar axes, but it is unclear whether a common mechanism governs different types of polar axis formation. The phosphorylation status of PIN proteins, which is directly affected by the PINOID （PID） protein kinase and the PP2A protein phosphatase, is known to regulate the apical-basal polarity of PIN localization in bipolar cells of roots and shoot apices. Here, we provide evidence that the phosphorylation status-mediated PIN polarity switch is widely used to modulate cellular processes in Arabidopsis including multipolar pavement cells （PC） with interdigitated lobes and indentations. The degree of PC interdigitation was greatly reduced either when the FYPP1 gene, which encodes a PP2A called phytochrome- associated serine/threonine protein phosphatase, was knocked out or when the PID gene was overexpressed （35S：：PID）. These genetic modifications caused PIN1 localization to switch from lobe to indentation regions. The PP2A and PID mediated switching of PIN1 localization is strikingly similar to their regulation of the apical-basal polarity switch of PIN proteins in other cells. Our findings suggest a common mechanism for the regulation of PIN1 polarity formation, a fundamental cellular process that is crucial for pattern formation both at the tissue/organ and cellular levels.

Information transmission is an important part of the wellbore trajectory automatic control system. Combined with the characteristics of the guided drilling system, drilling fluid pulse is selected as a tool for trajectory control. Negative pulse transmission of drilling fluid is one of the key technologies to realize wellbore trajectory automatic control. In this paper, the working principle of negative pulse propagation of drilling fluid is introduced. The characteristics of negative pulse propagation and signal pretreatment of drilling fluid are analyzed emphatically. Signal correlation analysis method is proposed for signal transmission of drilling fluid negative impulse well. In this paper, the propagation characteristics of drilling fluid pressure pulsed downward transmission system are studied deeply. The influence of various drilling parameters on the drilling fluid pressure pulse is analyzed, and the model of drilling fluid pressure pulse is presented. Experimental results show that the proposed method can effectively separate useful signals from interfering signals. It is verified by field experiment that the success rate of information decode system designed by this method is high, which can meet the requirement of well trajectory precise control.

In actual exploration, the demand for 3D seismic data collection is increasing, and the requirements for data are becoming higher and higher. Accordingly, the collection cost and data volume also increase. Aiming at this problem, we make use of the nature of data sparse expression, based on the theory of compressed sensing, to carry out the research on the efficient collection method of seismic data. It combines the collection of seismic data and the compression in data processing in practical work, breaking through the limitation of the traditional sampling frequency, and the sparse characteristics of the seismic signal are utilized to reconstruct the missing data. We focus on the key elements of the sampling matrix in the theory of compressed sensing, and study the methods of seismic data acquisition. According to the conditions that the compressed sensing sampling matrix needs to meet, we introduce a new random acquisition scheme, which introduces the widely used Low-density Parity-check (LDPC) sampling matrix in image processing into seismic exploration acquisition. Firstly, its properties are discussed and its conditions for satisfying the sampling matrix in compressed sensing are verified. Then the LDPC sampling method and the conventional data acquisition method are used to synthesize seismic data reconstruction experiments. The reconstruction results, signal-to-noise ratio and reconstruction error are compared to verify the seismic data based on sparse constraints. The LDPC sampling method improves the current seismic data reconstruction efficiency, reduces the exploration cost and the effectiveness and feasibility of the method.