New beetle species of the genus Lasiosyne (Coleoptera, Lasiosynidae) from the Late Jurassic and Early Cretaceous of Russia and Mongolia

Six new species of the genus Lasiosyne Tan et al., 2007, the type genus of the family Lasiosynidae Kirejtshuk et al., 2010, are described from Jurassic and Lower Cretaceous deposits of Mongolia and East Siberia: L. shartegiensis sp. nov., L. insculpta sp. nov., L. longitarsa sp. nov., L. cataphracta sp. nov., L. punctata sp. nov., and L. decora sp. nov. A modified diagnosis of the genus is proposed.     

A new species of Micromalthidae (Coleoptera) from the Rovno amber: 1. Adult morphology

Micromalthus priabonicus sp. nov. from the Late Eocene Rovno amber (Ukraine) is described. The new species is readily distinguished from M. eocenicus Kirejtshuk et al., 2010 from the Early Eocene amber of Oise in France by the shorter body, unequal length of antennomeres 3 and 4, ovate terminal antennomere, less transverse head, transverse scutellum, and by the considerably shortened adsutural elytral margin.     

First fossil representative of the family omalisidae (Coleoptera,Elateroidea sensu lato) from the Baltic amber

The paper describes Jantarokrama utilis Kovalev et Kirejtshuk, gen. et sp. nov., the first fossil representative of the family Omalisidae from the Upper Eocene Baltic amber, which is similar to the Recent Phaeopterus unicolor Costa, 1856, but distinguished from the latter by the larger and not so slender body, smaller distance between antennal insertions, longer antennae, wider prothorax with very convex anterior edge of the pronotum, and particularly by five completely exposed abdominal ventrites. The diagnosis of the new genus among generic taxa of Omalisidae and its similarity to Berendtimirus Winkler, 1987 (Berendtimiridae) are discussed.     

Orientisargidae fam. n., a new Jurassic family of Archisargoidea (Diptera,Brachycera), with review?of?Archisargidae from China

A pair of fly impressions is described as a new species of a new genus, Orientisargus illecebrosus gen. et sp. n., referred to a new family Orientisargidae fam. n. within Archisargoidea of Brachycera, Diptera. The systematic position of Orientisargidae is discussed. Daohugosargus gen. n. is proposed for Sharasargus eximius KY Zhang et al., 2008. Uranorhagionidae is a junior synonym for Archisargidae. Meanwhile, Mostovskisarginae is a junior synonym for Uranorhagionidae. Mostovskisargus JF Zhang, 2010 and Strenorhagio KY Zhang et al., 2010 are synonymized with Uranorhagio KY Zhang et al., 2010. Uranorhagio includes three species: Uranorhagio asymmetricus (KY Zhang et al., 2010), comb. n., Uranorhagio daohugouensis KY Zhang et al., 2010 and Uranorhagio deviatus (KY Zhang et al., 2010), comb. n. Strenorhagio grimaldi KY Zhang et al., 2010 is synonymous with Uranorhagio deviatus. Mostovskisargus portentosus JF Zhang, 2010, Mostovskisargus signatus JF Zhang, 2010 and Strenorhagio conjugovenius KY Zhang et al., 2010 are synonymous with Uranorhagio asymmetricus. Brevisolva KY Zhang et al., 2010 is a junior synonym for Mesosolva Hong, 1983. A new specific name, Mesosolva zhangae nom. n., is proposed for Brevisolva daohugouensis KY Zhang et al., 2010. Mesosolva jurassica KY Zhang et al., 2010 should be synonymized under Mostovskisargus sinensis KY Zhang et al., 2010. Sinallomyia nom. n. is proposed for Allomyia Ren, 1998. The systematic positions for Helempis eucalla Ren, 1998, Helempis yixianensis Ren, 1998, Pauromyia oresbia Ren, 1998 and Sinallomyia ruderalis (Ren, 1998) are reassessed. These taxa belong to Archisargidae rather than to Tabanidae, Rhagionidae and Protempididae, respectively.     

Two new genera of Lasiosynidae (Insecta,Coleoptera) from the Lower Cretaceous of Russia and Mongolia,and principal trends of the morphological evolution of the family

Two new monotypic genera of the family Lasiosynidae, Microsyne gen. nov. and Crassisyne gen. nov., are described from two Early Cretaceous localities: Baisa (Eastern Siberia, Zaza Formation) and Sharyn-Gol (Mongolia, Sharyn-Gol Formation): Peculiar morphological features of different lasiosynid genera and general trends of their morphological evolution are discussed.     

Yanliaoa, an extinct genus of Cupressaceae s. l. from the Middle Jurassic,northeastern China

Yanliaoa is a common fossil in the Middle Jurassic of western Liaoning, eastern Inner Mongolia and northern Hebei Province, China. It is an important element of the Yanliao biota. The genus was established by Pan in 1977 for fossil plants from the Middle Jurassic Haifanggou Formation in Xiasanjiaochengzi, western Liaoning Province, and in present paper, the genus Yanliaoa is studied based on new material. Pan never designated a type specimen and his fossil material cannot be located. We designate a type specimen here for Yanliaoa, so that the genus name Yanliaoa remains valid. Yanliaoa sinensis Pan emend. Tan et al., is found in the same locality and formation as the lost specimens, Y. sinensis of Pan, 1977. Yanliaoa daohugouensis n. sp., a new species with epidermal anatomy, is from the Middle Jurassic Daohugou, Inner Mongolia. A holotype is also selected from the new material for this new species. Characters of the leafy shoots and ovulate cones of Yanliaoa are emended. The epidermal anatomy of this genus is described for the first time. Compared with other extant and extinct species of Cupressaceae s. l., the current species can be distinguished from any known species both by the leafy shoot characters and its epidermal anatomy. It further indicates that Yanliaoa is an extinct and endemic conifer found in the Middle Jurassic of northeastern China.     

Testing the level of ant activity associated with quorum sensing: an empirical approach leading to the establishment and test of a null-model (response to the comment of Richardson et al.)

In a paper in this journal (Nouvellet et al., 2010), we presented results from experiments on the behaviour of the Pharaoh's ant, Monomorium pharaonis, along with a substantial statistical and theoretical analysis of the results. In a minor part of our paper, we compared our results with the related work of Richardson et al. (2010a). These authors have subsequently commented on our interpretation of their work (Richardson et al., 2011). In this Letter we respond to the comments of Richardson et al. (2011), and give detailed arguments why we stand by our original conclusions.     

Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations

Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low K_m for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion.Lignin in plant cell walls confers structural support, provides a hydrophobic coating of xylem vessels to facilitate water transport through the vascular system, and protects against invading plant pathogens (Vanholme et al., 2010). Lignin is a complex polymer derived principally from monolignol (hydroxycinnamyl alcohol) precursors and related compounds. The three primary monolignols are coniferyl, sinapyl, and p-coumaryl alcohols, which give rise to guaiacyl (G), syringyl (S), and p-hydroxyphenyl subunits in polymerized lignin (Ralph et al., 2004; Vanholme et al., 2010). Due to its physical association with cellulose and physicochemical associations with hemicellulosic polysaccharides, and its ability to bind cellulolytic enzymes irreversibly, lignin is a major obstacle for the large-scale production of cellulosic biofuels and chemicals (Berlin et al., 2006; Dien et al., 2009; Ximenes et al., 2010). Thus, manipulation of the monolignol biosynthetic pathway is being pursued as a way to lower the energy cost and reduce the processing time associated with thermochemical pretreatment of the biomass (Chen and Dixon, 2007; Vermerris et al., 2007; Dien et al., 2009). This approach has the risk of depriving the plants of a crucial structural component that may well lead to weaker plants and reduced agronomic performance. Examples illustrating this risk include brown midrib (bmr) double mutants of forage sorghum (Sorghum bicolor; Pedersen et al., 2008), maize (Zea mays; Vermerris et al., 2010), and transgenic alfalfa (Medicago sativa) plants with reduced hydroxycinnamoyl-coenzyme A:shikimate hydroxycinnamoyl transferase (HCT; Shadle et al., 2007). Thus, the potential success or failure of metabolic engineering efforts aimed at improving biomass conversion hinges on a thorough understanding of the target pathway as it exists in the species of interest (Humphreys et al., 1999; Sarath et al., 2008; Vanholme et al., 2008; Walker et al., 2013).Based on the current model of monolignol biosynthesis in angiosperms (Humphreys and Chapple, 2002), sinapyl alcohol is synthesized from precursors of guaiacyl residues, specifically coniferaldehyde and coniferyl alcohol, through the concerted action of the enzymes ferulate 5-hydroxylase (F5H) and caffeic acid O-methyltransferase (COMT). This model is based on kinetic studies with purified F5H from sweetgum (Liquidambar styraciflua; Osakabe et al., 1999) and Arabidopsis (Arabidopsis thaliana; Humphreys et al., 1999) that showed that F5H preferentially converted coniferaldehyde (Humphreys et al., 1999; Osakabe et al., 1999) and coniferyl alcohol (Humphreys et al., 1999) over ferulate. Consequently, coniferyl aldehyde/alcohol 5-hydroxylase is a more accurate name for this enzyme. COMT subsequently methylates the hydroxyl group on C5 of the phenolic ring.This model is also consistent with the observed reduction in the proportion of S-residues in the lignin of Arabidopsis fah1 mutants that carry mutations in the F5H gene (Meyer et al., 1996) and the marked increase in the proportion of S-residues that result from the overexpression of F5H (Meyer et al., 1998). The model is further supported by the observed reduction in the proportion of S-residues in plants in which COMT expression is down-regulated as the result of mutations or transgenic approaches (Chabbert et al., 1994; Atanassova et al., 1995; Van Doorsselaere et al., 1995; Guo et al., 2001; Bout and Vermerris, 2003; Marita et al., 2003; Fu et al., 2011; Jung et al., 2012; Sattler et al., 2012; Jung et al., 2013). In plants with reduced COMT activity, the low conversion of 5-hydroxyconiferaldehyde and 5-hydroxyconiferyl alcohol to the methylated derivatives leads to the incorporation of 5-hydroxyconiferyl alcohol into lignin, resulting in 5-hydroxyguaiacyl subunits in the polymer, as observed in maize bm3 mutants (Lapierre et al., 1988; Marita et al., 2003) and sorghum bmr12 mutants (Palmer et al., 2008). The incorporation of 5-hydroxyconiferyl alcohol into the growing lignin polymer also results in the formation of novel benzodioxane units (Ralph et al., 2001; Marita et al., 2003; Morreel et al., 2004).Caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) catalyzes the methylation reaction of caffeoyl-CoA to feruloyl-CoA (Martz et al., 1998), and this enzyme is thought to be responsible for the synthesis of the precursors of G-residues (Meng and Campbell, 1998). Down-regulation of CCoAOMT has indeed been shown to decrease G-lignin content in Pinus radiata (Wagner et al., 2011) and alfalfa (Guo et al., 2001). However, there are also data that potentially conflict with this model. In tobacco (Nicotiana tabacum), CCoAOMT has been shown to be able to methylate both 3- and 5-hydroxyl groups, with a strong preference for the thioester form of monolignol precursors (Martz et al., 1998). In alfalfa, COMT may be able to convert caffealdehyde to coniferaldehyde, suggesting some metabolic overlap between the biosynthetic routes toward precursors of G- and S-lignin (Parvathi et al., 2001). Furthermore, data on the effect of the down-regulation of COMT in alfalfa resulted in concomitant decreases in both G- and S-residues, again implicating COMT in the biosynthesis of coniferyl alcohol (Guo et al., 2001). The same was observed in transgenic ryegrass (Lolium perenne) in which the LpOMT1 gene had been down-regulated. The S-G ratio of the lignin in the transgenic plant was unaltered relative to the untransformed controls (Louie et al., 2010; Tu et al., 2010). Some ryegrasses are polyploid, and the presence of diverged paralogous OMT genes could potentially compensate for the reduced LpOMT1 expression. Alternatively, COMT in ryegrass may also play a role in the production of coniferaldehyde, so that its down-regulation would logically affect G-residues in the lignin, as proposed previously (Tu et al., 2010).This study focuses on COMT in sorghum for two main reasons. First, sorghum, along with switchgrass (Panicum virgatum), has been proposed as an attractive herbaceous biofuel feedstock in the United States, due to its potential to produce large amounts of biomass, superior drought tolerance, and more efficient utilization of nitrogen-based fertilizers than many other crops, including the two main crops currently used for the production of biofuels there, maize and sugarcane (Saccharum spp.; Sarath et al., 2008; Vermerris and Saballos, 2012). The production of cellulosic biofuels from sorghum and switchgrass would translate to a lower environmental impact associated with biofuel production (Vermerris et al., 2007; Propheter and Staggenborg, 2010; Wortmann and Regassa, 2011). Second, several bmr12 mutants with reduced COMT activity have been identified in sorghum (Bout and Vermerris, 2003; Saballos et al., 2008; Sattler et al., 2012). Because of their reduced lignin content and altered lignin subunit composition, they are promising as biomass feedstocks for biofuel production (Vermerris et al., 2007; Saballos et al., 2008; Dien et al., 2009; Sattler et al., 2010, 2012), but they are also of value to study the catalytic mechanism of COMT in this species. This will enable the elucidation of the main role of this enzyme and can form the basis of future protein engineering approaches to modify cell wall composition. Based on the genomic sequence of sorghum (Paterson et al., 2009), it possesses only a single gene encoding a functional S-adenosyl-l-methionine (SAM)-dependent COMT, making sorghum COMT (SbCOMT) an ideal candidate for the effective manipulation of monolignol biosynthesis (Bout and Vermerris, 2003; Sattler et al., 2012).We present here a range of data elucidated for SbCOMT, including crystal structures and thermodynamic and kinetic data, to gain a mechanistic understanding of this key enzyme and to enable future manipulation of the monolignol biosynthesis and lignin content of sorghum.     

PLASTID MOVEMENT IMPAIRED1 and PLASTID MOVEMENT IMPAIRED1-RELATED1 Mediate Photorelocation Movements of Both Chloroplasts and Nuclei

Organelle movement and positioning play important roles in fundamental cellular activities and adaptive responses to environmental stress in plants. To optimize photosynthetic light utilization, chloroplasts move toward weak blue light (the accumulation response) and escape from strong blue light (the avoidance response). Nuclei also move in response to strong blue light by utilizing the light-induced movement of attached plastids in leaf cells. Blue light receptor phototropins and several factors for chloroplast photorelocation movement have been identified through molecular genetic analysis of Arabidopsis (Arabidopsis thaliana). PLASTID MOVEMENT IMPAIRED1 (PMI1) is a plant-specific C2-domain protein that is required for efficient chloroplast photorelocation movement. There are two PLASTID MOVEMENT IMPAIRED1-RELATED (PMIR) genes, PMIR1 and PMIR2, in the Arabidopsis genome. However, the mechanism in which PMI1 regulates chloroplast and nuclear photorelocation movements and the involvement of PMIR1 and PMIR2 in these organelle movements remained unknown. Here, we analyzed chloroplast and nuclear photorelocation movements in mutant lines of PMI1, PMIR1, and PMIR2. In mesophyll cells, the pmi1 single mutant showed severe defects in both chloroplast and nuclear photorelocation movements resulting from the impaired regulation of chloroplast-actin filaments. In pavement cells, pmi1 mutant plants were partially defective in both plastid and nuclear photorelocation movements, but pmi1pmir1 and pmi1pmir1pmir2 mutant lines lacked the blue light-induced movement responses of plastids and nuclei completely. These results indicated that PMI1 is essential for chloroplast and nuclear photorelocation movements in mesophyll cells and that both PMI1 and PMIR1 are indispensable for photorelocation movements of plastids and thus, nuclei in pavement cells.In plants, organelles move within the cell and become appropriately positioned to accomplish their functions and adapt to the environment (for review, see Wada and Suetsugu, 2004). Light-induced chloroplast movement (chloroplast photorelocation movement) is one of the best characterized organelle movements in plants (Suetsugu and Wada, 2012). Under weak light conditions, chloroplasts move toward light to capture light efficiently (the accumulation response; Zurzycki, 1955). Under strong light conditions, chloroplasts escape from light to avoid photodamage (the avoidance response; Kasahara et al., 2002; Sztatelman et al., 2010; Davis and Hangarter, 2012; Cazzaniga et al., 2013). In most green plant species, these responses are induced primarily by the blue light receptor phototropin (phot) in response to a range of wavelengths from UVA to blue light (approximately 320–500 nm; for review, see Suetsugu and Wada, 2012; Wada and Suetsugu, 2013; Kong and Wada, 2014). Phot-mediated chloroplast movement has been shown in land plants, such as Arabidopsis (Arabidopsis thaliana; Jarillo et al., 2001; Kagawa et al., 2001; Sakai et al., 2001), the fern Adiantum capillus-veneris (Kagawa et al., 2004), the moss Physcomitrella patens (Kasahara et al., 2004), and the liverwort Marchantia polymorpha (Komatsu et al., 2014). Two phots in Arabidopsis, phot1 and phot2, redundantly mediate the accumulation response (Sakai et al., 2001), whereas phot2 primarily regulates the avoidance response (Jarillo et al., 2001; Kagawa et al., 2001; Luesse et al., 2010). M. polymorpha has only one phot that mediates both the accumulation and avoidance responses (Komatsu et al., 2014), although two or more phots mediate chloroplast photorelocation movement in A. capillus-veneris (Kagawa et al., 2004) and P. patens (Kasahara et al., 2004). Thus, duplication and functional diversification of PHOT genes have occurred during land plant evolution, and plants have gained a sophisticated light sensing system for chloroplast photorelocation movement.In general, movements of plant organelles, including chloroplasts, are dependent on actin filaments (for review, see Wada and Suetsugu, 2004). Most organelles common in eukaryotes, such as mitochondria, peroxisomes, and Golgi bodies, use the myosin motor for their movements, but there is no clear evidence that chloroplast movement is myosin dependent (for review, see Suetsugu et al., 2010a). Land plants have innovated a novel actin-based motility system that is specialized for chloroplast movement as well as a photoreceptor system (for review, see Suetsugu et al., 2010a; Wada and Suetsugu, 2013; Kong and Wada, 2014). Chloroplast-actin (cp-actin) filaments, which were first found in Arabidopsis, are short actin filaments specifically localized around the chloroplast periphery at the interface between the chloroplast and the plasma membrane (Kadota et al., 2009). Strong blue light induces the rapid disappearance of cp-actin filaments and then, their subsequent reappearance preferentially at the front region of the moving chloroplasts. This asymmetric distribution of cp-actin filaments is essential for directional chloroplast movement (Kadota et al., 2009; Kong et al., 2013a). The greater the difference in the amount of cp-actin filaments between the front and rear regions of chloroplasts becomes, the faster the chloroplasts move, in which the magnitude of the difference is determined by fluence rate (Kagawa and Wada, 2004; Kadota et al., 2009; Kong et al., 2013a). Strong blue light-induced disappearance of cp-actin filaments is regulated in a phot2-dependent manner before the intensive polymerization of cp-actin filaments at the front region occurs (Kadota et al., 2009; Ichikawa et al., 2011; Kong et al., 2013a). This phot2-dependent response contributes to the greater difference in the amount of cp-actin filaments between the front and rear regions of chloroplasts. Similar behavior of cp-actin filaments has also been observed in A. capillus-veneris (Tsuboi and Wada, 2012) and P. patens (Yamashita et al., 2011).Like chloroplasts, nuclei also show light-mediated movement and positioning (nuclear photorelocation movement) in land plants (for review, see Higa et al., 2014b). In gametophytic cells of A. capillus-veneris, weak light induced the accumulation responses of both chloroplasts and nuclei, whereas strong light induced avoidance responses (Kagawa and Wada, 1993, 1995; Tsuboi et al., 2007). However, in mesophyll cells of Arabidopsis, strong blue light induced both chloroplast and nuclear avoidance responses, but weak blue light induced only the chloroplast accumulation response (Iwabuchi et al., 2007, 2010; Higa et al., 2014a). In Arabidopsis pavement cells, small numbers of tiny plastids were found and showed autofluorescence under the confocal laser-scanning microscopy (Iwabuchi et al., 2010; Higa et al., 2014a). Hereafter, the plastid in the pavement cells is called the pavement cell plastid. Strong blue light-induced avoidance responses of pavement cell plastids and nuclei were induced in a phot2-dependent manner, but the accumulation response was not detected for either organelle (Iwabuchi et al., 2007, 2010; Higa et al., 2014a). In both Arabidopsis and A. capillus-veneris, phots mediate nuclear photorelocation movement, and phot2 mediates the nuclear avoidance response (Iwabuchi et al., 2007, 2010; Tsuboi et al., 2007). The nuclear avoidance response is dependent on actin filaments in both mesophyll and pavement cells of Arabidopsis (Iwabuchi et al., 2010). Recently, it was shown that the nuclear avoidance response relies on cp-actin-dependent movement of pavement cell plastids, where nuclei are associated with pavement cell plastids of Arabidopsis (Higa et al., 2014a). In mesophyll cells, nuclear avoidance response is likely dependent on cp-actin filament-mediated chloroplast movement, because the mutants deficient in chloroplast movement were also defective in nuclear avoidance response (Higa et al., 2014a). Thus, phots mediate both chloroplast (and pavement cell plastid) and nuclear photorelocation movement by regulating cp-actin filaments.Molecular genetic analyses of Arabidopsis mutants deficient in chloroplast photorelocation movement have identified many molecular factors involved in signal transduction and/or motility systems as well as those involved in the photoreceptor system for chloroplast photorelocation movement (and thus, nuclear photorelocation movement; for review, see Suetsugu and Wada, 2012; Wada and Suetsugu, 2013; Kong and Wada, 2014). CHLOROPLAST UNUSUAL POSITIONING1 (CHUP1; Oikawa et al., 2003) and KINESIN-LIKE PROTEIN FOR ACTIN-BASED CHLOROPLAST MOVEMENT (KAC; Suetsugu et al., 2010b) are key factors for generating and/or maintaining cp-actin filaments. Both proteins are highly conserved in land plants and essential for the movement and attachment of chloroplasts to the plasma membrane in Arabidopsis (Oikawa et al., 2003, 2008; Suetsugu et al., 2010b), A. capillus-veneris (Suetsugu et al., 2012), and P. patens (Suetsugu et al., 2012; Usami et al., 2012). CHUP1 is localized on the chloroplast outer membrane and binds to globular and filamentous actins and profilin in vitro (Oikawa et al., 2003, 2008; Schmidt von Braun and Schleiff, 2008). Although KAC is a kinesin-like protein, it lacks microtubule-dependent motor activity but has filamentous actin binding activity (Suetsugu et al., 2010b). An actin-bundling protein THRUMIN1 (THRUM1) is required for efficient chloroplast photorelocation movement (Whippo et al., 2011) and interacts with cp-actin filaments (Kong et al., 2013a). chup1 and kac mutant plants were shown to lack detectable cp-actin filaments (Kadota et al., 2009; Suetsugu et al., 2010b; Ichikawa et al., 2011; Kong et al., 2013a). Similarly, cp-actin filaments were rarely detected in thrum1 mutant plants (Kong et al., 2013a), indicating that THRUM1 also plays an important role in maintaining cp-actin filaments.Other proteins J-DOMAIN PROTEIN REQUIRED FOR CHLOROPLAST ACCUMULATION RESPONSE1 (JAC1; Suetsugu et al., 2005), WEAK CHLOROPLAST MOVEMENT UNDER BLUE LIGHT1 (WEB1; Kodama et al., 2010), and PLASTID MOVEMENT IMPAIRED2 (PMI2; Luesse et al., 2006; Kodama et al., 2010) are involved in the light regulation of cp-actin filaments and chloroplast photorelocation movement. JAC1 is an auxilin-like J-domain protein that mediates the chloroplast accumulation response through its J-domain function (Suetsugu et al., 2005; Takano et al., 2010). WEB1 and PMI2 are coiled-coil proteins that interact with each other (Kodama et al., 2010). Although web1 and pmi2 were partially defective in the avoidance response, the jac1 mutation completely suppressed the phenotype of web1 and pmi2, suggesting that the WEB1/PMI2 complex suppresses JAC1 function (i.e. the accumulation response) under strong light conditions (Kodama et al., 2010). Both web1 and pmi2 showed impaired disappearance of cp-actin filaments in response to strong blue light (Kodama et al., 2010). However, the exact molecular functions of these proteins are unknown.In this study, we characterized mutant plants deficient in the PMI1 gene and two homologous genes PLASTID MOVEMENT IMPAIRED1-RELATED1 (PMIR1) and PMIR2. PMI1 was identified through molecular genetic analyses of pmi1 mutants that showed severe defects in chloroplast accumulation and avoidance responses (DeBlasio et al., 2005). PMI1 is a plant-specific C2-domain protein (DeBlasio et al., 2005; Zhang and Aravind, 2010), but its roles and those of PMIRs in cp-actin-mediated chloroplast and nuclear photorelocation movements remained unclear. Thus, we analyzed chloroplast and nuclear photorelocation movements in the single, double, and triple mutants of pmi1, pmir1, and pmir2.