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Pollen undergo a maturation process to sustain pollen viability and prepare them for germination. Molecular mechanisms controlling these processes remain largely unknown. Here, we report an Arabidopsis thaliana mutant, dayu (dau), which impairs pollen maturation and in vivo germination. Molecular analysis indicated that DAU encodes the peroxisomal...
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... required for the formation of nascent peroxisomes and import of peroxisomal membrane proteins (Götte et al., 1998; Ghaedi et al., 2000; Kim et al., 2006; Matsuzaki and Fujiki, 2008). PEX16 localized both in the endoplasmic reticulum (ER) and peroxisome is involved in early peroxisome biogenesis (Karnik and Trelease, 2005; Kim et al., 2006; Mullen and Trelease, 2006). Peroxisome matrix proteins, tagged by PTS1 or PTS2 peptide signals, are synthesized on free polyribosomes and imported into peroxisomes posttranslationally. PTS1- and PTS2-containing proteins are fi rst recognized by receptors PEX5 and PEX7, respectively, in the cytosol (Dammai and Subramani, 2001; Hayashi et al., 2005; Singh et al., 2009; Ramón and Bartel, 2010). Next, the receptor-cargo complex docks onto the peroxisomal membrane proteins PEX13 and PEX14 (Hayashi et al., 2000; Mano et al., 2006; Singh et al., 2009), and then the cargoes are released in the peroxisome and the receptors are recycled back to the cytosol. The recycling machinery requires the RING- fi nger E3 ligase complex composed of PEX2, PEX10, and PEX12 (Dammai and Subramani, 2001; Schumann et al., 2003; Sparkes et al., 2003; Fan et al., 2005; Nito et al., 2007; Kaur et al., 2013), the ubiquitin-conjugating enzyme PEX4 anchored to the membrane by PEX22 (Zolman et al., 2005; Nito et al., 2007), and the APEM9-tethered AAA-ATPase PEX1- PEX6 complex (Grou et al., 2009; Goto et al., 2011). Peroxisomes in plants display profound metabolic plasticity manifested by their diverse function and morphology. They are the site of fatty acid b -oxidation in plant cells and involved in the generation of phytohormones JA and indole-3-acetic acid as well as in other metabolic and signaling pathways. OPR3 converts the chloroplast-produced 12-oxophytodienoic acid to OPC8:0, which is converted to JA after three rounds of b -oxidation in the peroxisome (Turner et al., 2002; Hu et al., 2012). Consistently, the male sterility of opr3 can be rescued by exogenous JA but not 12-oxophytodienoic acid (Stintzi and Browse, 2000). The biogenesis and function of peroxisomes in reproduction are largely unknown in plants. Recently, it was reported that ABSTI- NENCE BY MUTUAL CONSENT ( AMC ), a putative ortholog of PEX13 , is involved in male-female gametophyte recognition, but the mechanism remains unknown (Boisson-Dernier et al., 2008). Here, we identi fi ed a male gametophytic mutant dayu ( dau ) in Arabidopsis , which is defective in pollen maturation and germination in planta. DAU encodes a peroxisomal membrane protein recently identi fi ed as APEM9 (Goto et al., 2011). Peroxisome bio- genesis/function and matrix protein import were both impaired in dau pollen, and the male sterility of dau/DAU plants was partially restored by the exogenous application of JA. A similar phenotype was observed in pex13 but not in pex10 , pex12 , pex14 , or pex16 mutants, suggesting that peroxins likely play different roles in pollen. We also found that DAU is a dual transmembrane protein that interacts with PEX13 and PEX16 in plants. Together, we showed that DAU/APEM9, which is required for peroxisome biogenesis and function, plays a critical role during pollen maturation/germination. To understand mechanisms controlling pollen development, we performed a genetic screen for mutants with a distorted Mendelian segregation from our Arabidopsis gene/enhancer trap lines (Sundaresan et al., 1995; Page and Grossniklaus, 2002). A gene trap line, designated as dayu ( dau , after the Chinese legendary hero), exhibited a kanamycin-resistant ( Kan r ) to kanamycin-sensitive ( Kan s ) ratio of 1.28:1 (370:289). Further reciprocal crosses between dau/DAU and wild-type plants showed a Kan r : Kan s ratio of 0.88:1 (191:216) in F1 progenies when dau/DAU plants were used as the female and of 0.13:1 (55:415) when dau/DAU plants as the male. These data suggest that the dau mutation causes severe defects in the male gametophyte. In addition, no homozygous dau mutant was obtained, indicating that the mutation might cause embryo lethality. Therefore, we examined the embryo development from the self-pollinated dau/DAU plants and found that ; 17.10% of embryos ( n = 1158) displayed obvious abortion. The mutant embryos were arrested at the heart stage and were ultimately shrunk (Supplemental Figure 1). Since the function of the male gametophyte is impaired in the dau mutant, the viability of mature pollen was investigated with Alexander ’ s stain (Alexander, 1969). The viable wild-type pollen were stained red purple (Figure 1A), while a few aborted pollen from dau / DAU plants were not stained (Figure 1B). Statistical analysis indicates that the wild-type pollen have an abortion rate of 0.90% ( n = 2116), while dau / DAU plants grown in the same conditions have a pollen abortion rate of 4.80% ( n = 8536) (Student ’ s t test, 0.01 < P < 0.05). We further examined the pollen morphology by scanning electron microscopy. Quartet pollen grains (Preuss et al., 1994; Copenhaver et al., 2000) from DAU/DAU qrt/qrt and dau/DAU qrt/qrt plants were collected for the scanning electron microscopy analysis (Figures 1C and 1D). Compared with the wild-type pollen (Figure 1C) with an abortion ratio of 0.61% ( n = 653), the majority of pollen grains from dau/DAU qrt/qrt plants were morphologically normal except for 4.01% pollen ( n = 873, Student ’ s t test, P < 0.01), which were small and shrunken (Figure 1D). These data indicate that pollen viability is slightly affected in the dau mutant. To assess whether the dau mutation impairs pollen development, pollen grains from dau/DAU qrt/qrt plants were stained with 4 9 ,6-diamidino-2-phenylindole (DAPI) to check cell cycle progression. At stages of pollen mitosis I and II, the quartet pollen grains from dau/DAU qrt/qrt plants, which have two wild- type grains and two dau grains, displayed a similar nuclear appearance (Supplemental Figure 2), indicating that pollen development is normal at these stages. Among the mature quartet pollen released from dau/DAU qrt/qrt anthers ( n = 1104), 81.70% contained three clearly stained nuclei (Figure 1E), 12.41% showed three visible nuclei with faint staining (Figure 1F), and 5.89% contained totally disrupted nuclei (Figure 1G). In comparison, the mature pollen from DAU/DAU qrt/qrt anthers had an abortion ratio of 0.88% ( n = 1026). These data indicate that the pollen grains from dau/DAU qrt/qrt plants develop normally up to the tricellular stage; thereafter, a small fraction of the mutant pollen is disrupted during maturation. Since the tricellular pollen in undehisced anthers have gained pollination competence (Kandasamy et al., 1994), we wondered whether the dau tricellular pollen within anthers were functional. When tricellular ...
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... Analyses suggest that APEM9 tethers the PEX1-PEX6 complex to the peroxisomal membrane, and the apem9-1 mutation disrupts the peroxisomal localization of APEM9 and the PEX1-PEX6 complex because the mutation is located in the transmembrane domain of APEM9; this suggests that the role of APEM9 is the same as that of Pex15p in yeast and PEX26 in mammals [41]. The Arabidopsis dayu mutant is characterized by abnormal pollen maturation and germination [70]. DAY U encodes APEM9. ...
... DAY U encodes APEM9. DAYU/APEM9 binds to PEX13, a factor of the import complex (Figure 1), suggesting that DAYU/APEM9 is involved in the import of both PTS1-and PTS2-containing proteins in addition to mediating receptor export by the ubiquitin system [70]. Moreover, the pex26-1 mutant, which was isolated as one of the ibr mutants [46], shows a more severe phenotype than apem9-1. ...
Peroxisomes are ubiquitous organelles present in most eukaryotic cells that have important biological functions related to fatty acid metabolism and detoxification of reactive oxygen species. Disruption of peroxisomal function affects the survival of cells and organisms. Peroxisomes do not have their own genome, and peroxisomal proteins are encoded in the nuclear genome. Therefore, efficient and accurate posttranslational transport of peroxisomal proteins is necessary to maintain peroxisomal function. In mammals, yeast, and plants, many factors involved in protein transport to peroxisomes have been identified and their molecular mechanisms elucidated. In plants, analysis of Arabidopsis peroxisome mutants, such as apem (aberrant peroxisome morphology) and ibr (indole-3-butyric acid-response), enabled the identification of the factors mediating protein transport. Of these, several proteins, such as PEX1 (Peroxin 1), PEX2, PEX4, PEX6, PEX10, PEX12, PEX22, and APEM9, constitute the ubiquitin system on the peroxisomal membrane, and loss of function of each protein reduces the efficiency of protein transport to peroxisomes. This ubiquitin-dependent peroxisomal protein transport system is also present in yeast and mammalian cells and is an example of a type of ubiquitin modification that serves as a signaling tag rather than as a tag for protein degradation. This chapter introduces the factors involved in protein transport to the peroxisome via the ubiquitin system in plants and outlines their functions.
... The apem9 mutation substitutes Gly278 with Glu in the transmembrane domain, which affects the peroxisomal localization of APEM9 and the PEX1/PEX6 complex (Goto et al., 2011). DAYU (a synonym of APEM9) binds to PEX13 and PEX16 (Li et al., 2014). As described above, PEX13 is a component of the PEX5 docking complex, and bridging the docking complex closer to the recycling machinery may make export of PEX5 efficient. ...
... The E2 ubiquitin ligase PEX4 and the E3 ligase PEX2/PEX10/PEX12 supposedly ubiquitinate PEX5 to export it from the peroxisomal membrane with/without the force generated by the APEM9/PEX15/PEX26-tethered AAA-ATPase PEX1-PEX6 complex. Experimental data support the interactions between PEX13 and PEX7 (Mano et al., 2006), PEX13 and PEX15/PEX26 (Li et al., 2014), and PEX7 and PEX12 (Singh et al., 2009) ...
Peroxisomes are present in eukaryotic cells and have essential roles in various biological processes. Plant peroxisomes proliferate by de novo biosynthesis or division of pre-existing peroxisomes, degrade, or replace metabolic enzymes, in response to developmental stages, environmental changes, or external stimuli. Defects of peroxisome functions and biogenesis alter a variety of biological processes and cause aberrant plant growth. Traditionally, peroxisomal function-based screening has been employed to isolate Arabidopsis thaliana mutants that are defective in peroxisomal metabolism, such as lipid degradation and photorespiration. These analyses have revealed that the number, subcellular localization, and activity of peroxisomes are closely related to their efficient function, and the molecular mechanisms underlying peroxisome dynamics including organelle biogenesis, protein transport, and organelle interactions must be understood. Various approaches have been adopted to identify factors involved in peroxisome dynamics. With the development of imaging techniques and fluorescent proteins, peroxisome research has been accelerated. Image-based analyses provide intriguing results concerning the movement, morphology, and number of peroxisomes that were hard to obtain by other approaches. This review addresses image-based analysis of peroxisome dynamics in plants, especially A. thaliana and Marchantia polymorpha .
... Four genotypes belonging to three Capsicum species i.e. two from C. annuum (labeled as S1; Dudu and S2; Iscjk), and one each from C. chinense (S3; Chin7) and C. frutescens (S4; frt4), were grown in the greenhouse of School of Life Sciences, Jawaharlal Nehru University, New Delhi, India using standard growth conditions including temperature 27/19°C (day/night) and 16 h/day. For DNA/RNA extraction, fruit from different developmental stages i.e. immature [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Days post anthesis (DPA)], breaker (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) and mature (45-60 DPA) stages from each of the above mentioned genotypes were collected separately in liquid nitrogen and stored at −80°C. ...
... However, their GO terms suggest their potential involvement in fruit development/ripening. For example in Arabidopsis, gene APEM9-like [LOC107856753 in Capsicum] is reported to be involved in the biogenesis of peroxisomes [42] as well as in movement of substances through, from or across the peroxisomal membrane. Peroxisomes have crucial roles in multiple metabolic processes like detoxification, betaoxidation of fatty acids etc. [23]. ...
Single-base cytosine methylation analysis across fruits of Capsicum annuum, C. chinense and C. frutescens showed global average methylation ranging from 82.8–89.1%, 77.6–83.9%, and 22.4–25% at CG, CHG and CHH contexts, respectively. High gene-body methylation at CG and CHG was observed across Capsicum species. The C. annuum showed the highest proportion (>80%) of mCs at different genomic regions compared to C. chinense and C. frutescens. Cytosine methylation for transposable-elements were lower in C. frutescens compared to C. annuum and C. chinense. A total of 510,165 CG, 583112 CHG and 277,897 CHH DMRs were identified across three Capsicum species. Moreover, differentially methylated regions (DMRs) distribution suggested C. frutescens as hypo-methylated than C. annuum and C. chinense and also intergenic DMRs are predominant in Capsicum genome. At CG, CHG context, gene expression and promoter methylation showed inverse correlation. Moreover, methylation correlation with expressed genes suggested potential role of methylation in Capsicum fruit development/ripening.
... Plant peroxisomes involved in numerous physiological processes, containing phytohormone biosynthesis, lipid catabolism, reactive oxygen species metabolism, and many others [40][41][42]. It was previously found that Peroxisome morphology9 (APEM9) mediates pollen maturation/germination of which participating in peroxisome biogenesis and function [43]. Interestingly, our data revealed that several genes involved in the pathway of peroxisome, including catalase-3 (c127728_g1), peroxisomal acyl-coenzyme A oxidase 3 (c119854_g1), hypothetical protein (c121573_g1 and c135528_g1), and peroxisomal acyl-coenzyme A oxidase 1-like (c119759_g2) were down-regulated 48 h after self-pollinated compared with cross-pollinated (Supplementary Table S22). ...
Camellia oleifera is a valuable woody oil plant belonging to the Theaceae, Camellia oil extracted from the seed is an excellent edible oil source. Self-incompatibility (SI) in C. oleifera results in low fruit set, and our knowledge about the mechanism remains limited. In the present study, the Tandem mass tag (TMT) based quantitative proteomics was employed to analyze the dynamic change of proteins response to self- and cross-pollinated in C. oleifera. A total of 6,616 quantified proteins were detected, and differentially abundant proteins (DAPs) analysis identified a large number of proteins. Combined analysis of differentially expressed genes (DEGs) and DAPs of self- and cross-pollinated pistils based on transcriptome and proteome data revealed that several candidate genes or proteins involved in SI of C. oleifera, including polygalacturonase inhibitor, UDP-glycosyltransferase 92A1-like, beta-D-galactosidase, S-adenosylmethionine synthetase, xyloglucan endotransglucosylase/hydrolase, ABC transporter G family member 36-like, and flavonol synthase. Venn diagram analysis identified 11 proteins that may participate in pollen tube growth in C. oleifera. Our data also revealed that the abundance of proteins related to peroxisome was altered in responses to SI in C. oleifera. Moreover, the pathway of lipid metabolism-related, flavonoid biosynthesis and splicesome were reduced in self-pollinated pistils by the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In summary, the results of the present study lay the foundation for learning the regulatory mechanism underlying SI responses as well as provides valuable protein resources for the construction of self-compatibility C. oleifera through genetic engineering in the future.
... The stained cotyledons were observed with a 488 nm and 543 nm laser of a Zeiss CLSM laser scanning microscope. Transmission electron microcopy was performed as previously reported 108 . ...
As one of the best-studied RNA binding proteins in plant, pentatricopeptide repeats (PPRs) protein are mainly targeted to mitochondria and/or chloroplasts for RNA processing to regulate the biogenesis and function of the organelles, but its molecular mechanism and role in development remain to be further revealed. Here, we identified a mitochondria-localized P-type small PPR protein, MITOCHONDRION-MEDIATED GROWTH DEFECT 1 (MID1) that is crucial for Arabidopsis development. Mutation in MID1 causes retarded embryo development and stunted plant growth with defects in cell expansion and proliferation. Molecular experiments showed that MID1 is required for the splicing of the nad2 intron 1 in mitochondria. Consistently, mid1 plants display significant reduction in the abundance and activity of mitochondrial respiration complex I, accompanied by abnormal mitochondrial morphology and energy metabolism. Furthermore, MID1 is associated with other trans-factors involved in NICOTINAMIDE ADENINE DINUCLEOTIDE HYDROGEN (NADH) DEHYDROGENASE SUBUNIT 2 (nad2) intron 1 splicing, and interacts directly with itself and MITOCHONDRIAL STABILITY FACTOR 1 (MTSF1). This suggests that MID1 most likely functions as a dimer for nad2 intron 1 splicing. Together, we characterized a novel PPR protein MID1 for nad2 intron 1 splicing.
... Pre-vacuolar compartment protein essential for pollen development and germination, knockout leads to male sterility in rice [71] 39 sbi-novel-miR-40-Sobic.009G012500 ...
... Though miR168-mediated AGO1 regulation has been previously shown [2], the role of miR168-AGO1 module in anther development has not been elucidated yet. miR169, on the other hand, targets ortholog of Arabidopsis PEX7 (PEROXIN7) implicated in pollen maturation and germination [71]. ...
Understanding male gametophyte development is essential to augment hybrid production in sorghum. Although small RNAs are known to critically influence anther/pollen development, their roles in sorghum reproduction have not been deciphered yet. Here, we report small RNA profiling and high-confidence annotation of microRNAs (miRNAs) from meiotic and post-meiotic anthers in sorghum. We identified 262 miRNAs (82 known and 180 novel), out of which 58 (35 known and 23 novel) exhibited differential expression between two stages. Out of 35 differentially expressed known miRNAs, 13 are known to regulate anther/pollen development in other plant species. We also demonstrated conserved spatiotemporal patterns of 21- and 24-nt phasiRNAs and their respective triggers, miR2118 and miR2275, in sorghum anthers as evidenced in other monocots. miRNA target identification yielded 5622 modules, of which 46 modules comprising 16 known and 8 novel miRNA families with 38 target genes are prospective candidates for engineering male fertility in grasses.
... The failure to establish homozygosity for silenced SlFAD7 plants suggests continuous selective pressure in favor of gametes where the transgene was lost. This explanation is in line with the reports that impaired jasmonate biosynthesis, for which plastidial 18:3 serves as the precursor, affects pollen maturation and germination (Li et al. 2014) and that JA plays a role also in ovule and embryo development (Goetz et al. 2012). ...
In tomato, desaturation of linoleic acid (18:2) to α-linolenic acid (18:3) is mediated in the plastidial membranes by the ω-3 fatty acid desaturases 7 (FAD7), and in the ER membrane by its paralog FAD3. According to the prevalent model, the hormone jasmonic acid isoleucine (JA-Ile), which plays a key role in the plant response to various stresses, including wounding and herbivores attack, is derived from 18:3 which is released from the plastidial membrane glycerolipids. The current work aimed at assessing in tomato the effects of ectopic FAD3 over-expression or SlFAD7 silencing on herbivore tolerance and on wound response. The tomato SlFAD7 gene encoding for the plastidial-residing FAD7 was silenced by RNA interference, and enhanced expression of the extra-plastidial ER-residing FAD3 was induced by ectopic expression of BnFAD3. Over-expression of BnFAD3 led to increase, whereas SlFAD7 silencing led to decrease in 18:3 content in the extra-plastidial and plastidial membrane, respectively. As anticipated, silencing SlFAD7 attenuated the accumulation of JA-Ile following wounding, and enhanced susceptibility to two important pest insects: the chewing herbivores Spodoptera littoralis and Heliothis peltigera. Unexpected was the finding that ectopic over-expression of the extra-plastidial ER-residing FAD3 accelerated both wound-induced JA-Ile accumulation and expression of wound-response marker genes. Furthermore, BnFAD3 over-expression significantly improved the tomato tolerance to these two chewing herbivores. The presented information supports the notion that 18:3 derived from extra-plastidial membranes may serve as a substrate for, or as a source for a cue triggering, JA-Ile biosynthesis in response to wounding and insect chewing.
... The Arabidopsis PEX16 mutation shrunken seed1 (sse1) confers inviable shrunken seeds (Lin et al. 1999). Peroxisomally-targeted reporters display diffuse localization rather than peroxisomal puncta in sse1 embryos from heterozygous SSE1/sse1 plants (Lin et al. 2004) and a mixture of diffuse localization and enlarged puncta in sse1 pollen grains (Li et al. 2014), suggesting defects in peroxisome biogenesis and/or matrix protein import. Interestingly, several sse1 seed phenotypes have not been reported in other Arabidopsis pex mutants. ...
... Arabidopsis PEX16 facilitates PMP insertion (Hua et al. 2015) and is implicated in de novo biogenesis and peroxisome fission during proliferation (Karnik and Trelease 2005). The only characterized Arabidopsis pex16 mutant, sse1, produces inviable seeds (Lin et al. 1999) despite retaining some enlarged peroxisomes in pollen grains (Li et al. 2014). ...
... Along with matrix protein mislocalization, we observed markedly enlarged peroxisomes in both pex16 mutants ( Figure 4A), as was also reported in a pex16 RNAi line (Nito et al. 2007) and pollen grains of the sse1 mutant (Li et al. 2014). Similarly, peroxisome biogenesis disorder patients with mutations at the C-terminus of PEX16 near the Arabidopsis pex16-1 mutation have relatively mild presentations but display reduced numbers of enlarged peroxisomes (Ebberink et al. 2010). ...
Peroxisomes rely on peroxins (PEX proteins) for biogenesis, importing membrane and matrix proteins, and fission. PEX16, which is implicated in peroxisomal membrane protein targeting and forming nascent peroxisomes from the endoplasmic reticulum (ER), is unusual among peroxins because it is inserted co‐translationally into the ER and localizes to both ER and peroxisomal membranes. PEX16 mutations in humans, yeast, and plants confer some common peroxisomal defects; however, apparent functional differences have impeded the development of a unified model for PEX16 action. The only reported pex16 mutant in plants, the Arabidopsis shrunken seed1 mutant, is inviable, complicating analysis of PEX16 function after embryogenesis. Here, we characterized two viable Arabidopsis pex16 alleles that accumulate negligible PEX16 protein levels. Both mutants displayed impaired peroxisome function − slowed consumption of stored oil bodies, decreased import of matrix proteins, and increased peroxisome size. Moreover, one pex16 allele exhibited reduced growth that could be alleviated by an external fixed carbon source, decreased responsiveness to peroxisomally processed hormone precursors, and worsened or improved peroxisome function in combination with other pex mutants. Because the mutations impact different regions of the PEX16 gene, these viable pex16 alleles allow assessment of the importance of Arabidopsis PEX16 and its functional domains.
... At the same time, this metabolic flexibility put the peroxisomes at the crossroad of different metabolic pathways, allowing the interrelationship of peroxisomes with other subcellular compartments, including oil bodies, plastids or mitochondria (Sunil et al. 2013;Sewelam et al. 2014;Demarquoy and Le Borgne 2015;van Wijk 2015;Palma et al. 2015;Kmiecik et al. 2016;Noctor and Foyer 2016). All these subcellular compartments are involved in many physiological processes, ranging from seed and pollen germination (Li et al. 2014), nitrogen metabolism, fatty acid b-oxidation, photorespiration, stomatal movement, senescence, fruit ripening, response to abiotic stresses (Smertenko 2017), to interactions among beneficial (Borucki 2007) and pathogenic micro-organisms (Kubo 2013;Sørhagen et al. 2013: Roos et al. 2014Zhong et al. 2016) (Figure 1). In fact, there are data suggesting that some ROS/RNS could function as retrograde signals (Fransen and Lismont 2018; Su et al. 2018). ...
... In recent years it has been reported that polyamine catabolism induces the synthesis of NO in different plant organs (Tun et al. 2006;Wimalasekera et al. 2011a;Yang et al. 2014;Diao et al. 2016;Agurla et al. 2018). In the catabolism of polyamines, polyamine oxidases and Cu-containing amine oxidases are involved, and in Arabidopsis thaliana isoform CuAO1 contributes to polyamine-induced NO biosynthesis, although the mechanism of this process is unknown (Wimalasekera et al. 2011b). ...
Plant peroxisomes are subcellular compartments involved in many biochemical pathways during the life cycle of a plant but also in the mechanism of response against adverse environmental conditions. These organelles have an active nitro‐oxidative metabolism under physiological conditions but this could be exacerbated under stress situations. Furthermore, peroxisomes have the capacity to proliferate and also undergo biochemical adaptations depending on the surrounding cellular status. An important characteristic of peroxisomes is that they have a dynamic metabolism of reactive nitrogen and oxygen species (RNS and ROS) which generates two key molecules, nitric oxide (NO) and hydrogen peroxide (H2O2). These molecules can exert signaling functions by means of post‐translational modifications that affect the functionality of target molecules like proteins, peptides or fatty acids. This review provides an overview of the endogenous metabolism of ROS and RNS in peroxisomes with special emphasis on polyamine and uric acid metabolism as well as the possibility that these organelles could be a source of signal molecules involved in the functional interconnection with other subcellular compartments.
... In association with ROS production, peroxisome targeted PAO (polyamine oxidase) has been reported to regulate pollen tube elongation 21 . A mutation in the peroxisomal membrane protein DAYU impairs pollen maturation and germination 22 . However, the association between anther dehiscence and peroxisomes remains unclear. ...
Male sterility in plants is caused by various stimuli such as hormone changes, stress, cytoplasmic alterations and nuclear gene mutations. The gene ANTHER DEHISCENCE REPRESSOR (ADR), which is involved in regulating male sterility in Arabidopsis, was functionally analyzed in this study. In ADR::GUS flowers, strong GUS activity was detected in the anthers of young flower buds but was low in mature flowers. ADR + GFP fusion proteins, which can be modified by N-myristoylation, were targeted to peroxisomes. Ectopic expression of ADR in transgenic Arabidopsis plants resulted in male sterility due to anther indehiscence. The defect in anther dehiscence in 35S::ADR flowers is due to the reduction of ROS accumulation, alteration of the secondary thickening in the anther endothecium and suppression of the expression of NST1 and NST2, which are required for anther dehiscence through regulation of secondary wall thickening in anther endothecial cells. This defect could be rescued by external application of hydrogen peroxide (H2O2). These results demonstrated that ADR must be N-myristoylated and targeted to the peroxisome during the early stages of flower development to negatively regulate anther dehiscence by suppressing ROS accumulation and NST1/NST2 expression.
