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Background: Flower phylogenetics and genetically controlled development have been revolutionised during the last two decades. However, some of these evolutionary aspects are still debatable. MADS-box genes are known to play essential role in specifying the floral organogenesis and differentiation in numerous model plants like Petunia hybrida, Arabidopsis thaliana and Antirrhinum majus. SEPALLATA (SEP) genes, belonging to the MADS-box gene family, are members of the ABCDE and quartet models of floral organ development and play a vital role in flower development. However, few studies of the genes in Prunus mume have yet been conducted. Results: In this study, we cloned four PmSEPs and investigated their phylogenetic relationship with other species. Expression pattern analyses and yeast two-hybrid assays of these four genes indicated their involvement in the floral organogenesis with PmSEP4 specifically related to specification of the prolificated flowers in P. mume. It was observed that the flower meristem was specified by PmSEP1 and PmSEP4, the sepal by PmSEP1 and PmSEP4, petals by PmSEP2 and PmSEP3, stamens by PmSEP2 and PmSEP3 and pistils by PmSEP2 and PmSEP3. Conclusion: With the above in mind, flower development in P. mume might be due to an expression of SEP genes. Our findings can provide a foundation for further investigations of the transcriptional factors governing flower development, their molecular mechanisms and genetic basis. [ABSTRACT FROM AUTHOR]

Anthocyanin production enhanced by heterologous expression of R2R3 MYB transcription factors has been studied. However, little is known about validated information on the ability of RsMYB (an MYB gene from radish) to enhance anthocyanin production in a heterologous system. In the present study, heterologous expression of RsMYB1 in Petunia hybrida ‘Mirage Rose’ enhanced anthocyanin production in vegetative and floral tissues such as leaves, stems, roots, and petals by transcriptional activation of anthocyanin biosynthetic genes and endogenous antocyanin regulatory genes. Line PM6 expressed higher transcript levels of RsMYB1 than line PM2 and regulated transcript levels of the investigated genes largely than line PM2, whereas those regulated in wild type (WT) plants were the lowest. In addition, transcript levels of the genes detected using qualitative real-time polymerase chain reaction were found to be higher in petals, followed by leaves, stems and roots. Taken together, our results suggest that RsMYB1 enhances anthocyanin production in vegetative and floral tissues of this cultivar, thus, we expect that heterologous expression of RsMYB1 would help to modify flower color of other ornamental plants as well. [ABSTRACT FROM AUTHOR]

Self-incompatibility ( SI) is a self/non-self discrimination system found widely in angiosperms and, in many species, is controlled by a single polymorphic S-locus. In the Solanaceae, Rosaceae and Plantaginaceae, the S-locus encodes a single S- RNase and a cluster of S-locus F-box ( SLF) proteins to control the pistil and pollen expression of SI, respectively. Previous studies have shown that their cytosolic interactions determine their recognition specificity, but the physical force between their interactions remains unclear. In this study, we show that the electrostatic potentials of SLF contribute to the pollen S specificity through a physical mechanism of 'like charges repel and unlike charges attract' between SLFs and S- RNases in Petunia hybrida. Strikingly, the alteration of a single C-terminal amino acid of SLF reversed its surface electrostatic potentials and subsequently the pollen S specificity. Collectively, our results reveal that the electrostatic potentials act as a major physical force between cytosolic SLFs and S- RNases, providing a mechanistic insight into the self/non-self discrimination between cytosolic proteins in angiosperms. [ABSTRACT FROM AUTHOR]

There has been little investigation into the effects of ozone (O3) on flowering plants around settlements, even though such plants are known to be threatened by elevated O3. In this study, we used open-top chambers to assess the ornamental value of marigolds (Tagetes erecta Linn.) and four petunia (Petunia hybrid Vilm.) varieties in terms of their growth and physiological responses to elevated O3. The aboveground biomass decreased by 7.4% in marigolds and by 19.4-23.6% in four varieties of petunia in response to elevated O3. The underground biomass decreased by 22.0% in marigolds and by 30.8-53.8% in four petunia varieties treated with elevated O3. Flower biomass and diameter were markedly reduced by elevated O3 in petunias, but not in marigolds. O3 also accelerated leaf yellowing in different plant species and varieties, owing to a higher degree of degradation of chlorophyll than carotenoids, as well as an increase in flavonoid contents. Thus, O3 stress responses should be considered when choosing flowering plants for their ornamental value. [ABSTRACT FROM AUTHOR]

As a first line of defense against insect herbivores many plants store high concentrations of toxic and deterrent secondary metabolites in glandular trichomes. Plant Pleiotropic Drug Resistance (PDR)-type ABC transporters are known secondary metabolite transporters, and several have been implicated in pathogen or herbivore defense. Here, we report on Petunia hybrida PhPDR2 as a major contributor to trichome-related chemical defense. PhPDR2 was found to localize to the plasma membrane and be predominantly expressed in multicellular glandular trichomes of leaves and stems. Down-regulation of PhPDR2 via RNA interference ( pdr2) resulted in a markedly higher susceptibility of the transgenic plants to the generalist foliage feeder Spodoptera littoralis. Untargeted screening of pdr2 trichome metabolite contents showed a significant decrease in petuniasterone and petuniolide content, compounds, which had previously been shown to act as potent toxins against various insects. Our findings suggest that PhPDR2 plays a leading role in controlling petuniasterone levels in leaves and trichomes of petunia, thus contributing to herbivory resistance. [ABSTRACT FROM AUTHOR]

Self-incompatibility (SI) in flowering plants is a genetic reproductive barrier to distinguish self- and non-self pollen to promote outbreeding. In Solanaceae, self-pollen is rejected by the ribonucleases expressed in the styles (S-RNases), via its cytotoxic function. On the other side, the male-determinant is the S-locus F-box proteins (SLFs) expressed in pollen. Multiple SLFs collaboratively detoxify non-self S-RNases, therefore, non-self recognition is the mode of self-/non-self discrimination in Solanaceae. It is considered that SLFs function as a substrate-recognition module of the Skp1-Cullin 1-F-box (SCF) complex that inactivates non-self S-RNases via their polyubiquitination, which leads to degradation by 26S proteasome. In fact, PhSSK1 (Petunia hybrida SLF-interacting Skp1-like1) was identified as a specific component of SCFSLF and was shown to be essential for detoxification of S-RNase in Petunia. However, different molecules are proposed as the candidate Cullin1, another component of SCFSLF, and there is as yet no definite conclusion. Here, we identified five Cullin1s from the expressed sequence tags (ESTs) derived from the male reproductive organ in Petunia. Among them, only PhCUL1-P was co-immunoprecipitated with S7-SLF2. In vitro protein-binding assay suggested that PhSSK1 specifically forms a complex with PhCUL1-P in an SLF-dependent manner. Knockdown of PhCUL1-P suppressed fertility of transgenic pollen in cross-compatible pollination in the functional S-RNase-dependent manner. These results suggested that SCFSLF selectively uses PhCUL1-P. Phylogeny of Cullin1s indicates that CUL1-P is recruited into the SI machinery during the evolution of Solanaceae, suggesting that the SI components have evolved differently among species in Solanaceae and Rosaceae, despite both families sharing the S-RNase-based SI. [ABSTRACT FROM AUTHOR]

This study aimed to determine ways to improve the growth and salt tolerance of petunia. Effects of polyamines (PAs; spermidine [Spd], spermine [Spm], and putrescine [Put]) and a nitric oxide (NO) donor (sodium nitroprusside [SNP]) were investigated. Initially, we screened petunia cultivars against sodium chloride (0–125 mM). The petunia cultivar Hurrah Red was identified as salt-sensitive cultivar in the basis of salt-effect on seed germination, fresh weight, and root length of seedlings. Treatment of Hurrah Red shoots with nitrogenous compounds improved the number, length, and fresh weight of roots, as well as the length and fresh weight of shoots over those of the control. Furthermore, plantlets rooted in an optimal concentration of Spd (34.5 µM), Spm (24.8 µM), Put (62.1 µM), and SNP (3.9 µM) were treated with 200 mM NaCl for 3 days to assess their tolerance level. Salt-affected plantlets showed higher level of lipid peroxidation, reduced catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO) activities and decreased contents of photosynthetic pigments and polyphenol than those of the control. PAs and SNP treatments significantly elevated photosynthetic pigments, enhanced antioxidant enzymes, and decreased lipid peroxidation in salt-stressed plantlets. Moreover, the growth and salt-tolerance response of petunia was highest when plantlets were exposed to SNP, followed by levels on treatment with Put, Spm, and Spd. Thus, the findings of this study suggested that treatment with exogenous SNP, Put, Spm, and Spd could protect petunia plants against soil salinity and improve their commercial production. [ABSTRACT FROM PUBLISHER]

Background: Adventitious root (AR) formation in axillary shoot tip cuttings is a crucial physiological process for ornamental propagation that is utilised in global production chains for young plants. In this process, the nitrogen and carbohydrate metabolisms of a cutting are regulated by its total nitrogen content (Nt), dark exposure during transport and irradiance levels at distinct production sites and phases through a specific plasticity to readjust metabolite pools. Here, we examined how elevated Nt contents with a combined dark exposure of cuttings influence their internal N-pools including free amino acids and considered early anatomic events of AR formation as well as further root development in Petunia hybrida cuttings. Results: Enhanced Nt contents of unrooted cuttings resulted in elevated total free amino acid levels and in particular glutamate (glu) and glutamine (gln) in leaf and basal stem. N-allocation to mobile N-pools increased whereas the allocation to insoluble protein-N declined. A dark exposure of cuttings conserved initial Nt and nitrate-N, while it reduced insoluble protein-N and increased soluble protein, amino- and amide-N. The increase of amino acids mainly comprised asparagine (asn), aspartate (asp) and arginine (arg) in the leaves, with distinct tissue specific responses to an elevated N supply. Dark exposure induced an early transient rise of asp followed by a temporary increase of glu. A strong positive N effect of high Nt contents of cuttings on AR formation after 384 h was observed. Root meristematic cells developed at 72 h with a negligible difference for two Nt levels. After 168 h, an enhanced Nt accelerated AR formation and gave rise to first obvious fully developed roots while only meristems were formed with a low Nt. However, dark exposure for 168 h promoted AR formation particularly in cuttings with a low Nt to such an extent so that the benefit of the enhanced Nt was almost compensated. Combined dark exposure and low Nt of cuttings strongly reduced shoot growth during AR formation. Conclusions: The results indicate that both enhanced Nt content and dark exposure of cuttings reinforced N signals and mobile N resources in the stem base facilitated by senescence-related proteolysis in leaves. Based on our results, a model of N mobilisation concomitant with carbohydrate depletion and its significance for AR formation is postulated. [ABSTRACT FROM AUTHOR]

A unique feature of glandular trichomes of plants in the botanical family Solanaceae is that they produce sugar esters (SE), chemicals that have been shown to possess insecticidal, antifungal, and antibacterial properties. Sugar esters of tobacco ( Nicotiana tabacum ) provide pest resistance, and are important flavor precursors in oriental tobacco cultivars. Acyl moieties of SEs in Nicotiana spp., petunia, and tomato are shown to vary with respect to carbon length and isomer structure (2–12 carbon chain length; anteiso -, iso- , and straight-chain). Sugar esters and their acyl groups could serve as a model to explore the basis of phenotypic diversity and adaptation to natural and agricultural environments. However, information on the diversity of acyl composition among species, cultivars, and accessions is lacking. Herein, described is the analysis of SE acyl groups found in 21 accessions of Nicotiana obtusifolia (desert tobacco), six of Nicotiana occidentalis subsp. hesperis , three of Nicotiana alata , two of N . occidentalis , four modern tobacco cultivars, five petunia hybrids, and one accession each of a primitive potato ( Solanum berthaultii ) and tomato ( Solanum pennellii ). A total of 20 different acyl groups was observed that were represented differently among cultivars, species, and accessions. In Nicotiana species, acetate and iso- and anteiso- branched acids prevailed. Straight-chain groups (2–8 carbons) were prominent in petunias, while octanoic acid was prominent in N . alata and N . × sanderae . Two unexpected acyl groups, 8-methyl nonanoate and decanoate were found in N . occidentalis subsp. hesperis . Longer chain groups were found in the petunia, tomato, and potato species studied. [ABSTRACT FROM AUTHOR]

Floral volatile phenylpropanoids and benzenoids (VPBs) play important ecological functions and have potential economic applications. Little is known about how multi-factors in integration regulate the formation and emission of floral VPBs. In the present study, we investigated effects of multi factors including endogenous circadian clock, light, and temperature on the formation and emission of VPBs, which are major volatiles in flowers of Petunia × hybrida cv. ‘Mitchell Diploid’. Endogenous circadian clock was proposed as the most important factor regulating rhythmic emission of VPBs and expressions of structural genes involved in the upstream biosynthetic pathway of VPBs, but did not affect expression levels of structural genes involved in the downstream pathway and VPBs-related regulators. In contrast to light, temperature was a more constant factor affecting emission of VPBs. VPBs emission could be inhibited within a short time by increasing temperature. The information will contribute to our understanding of emission mechanism of floral volatiles. [ABSTRACT FROM AUTHOR]

The flower architectural trait of doubleness is a highly important breeding characteristic in the ornamental species petunia ( Petunia hybrida ). Here, we described the development of a near-isogenic line of a petunia population that segregated for single and double flower types. Sequence-related amplified polymorphism (SRAP) and simple sequence repeat (SSR) techniques, combined with bulked segregant analysis (BSA) were used to develop molecular markers linked to this floral trait. From a survey of 170 SRAP and 38 SSR primer combinations, one SRAP marker and one SSR marker were found to be linked to the target trait, each leading to the amplification of a specific band in double flower petunia. The two markers were verified in a population of 1065 plants, including 478 single flower and 587 double flower petunia individuals, and were shown to be tightly linked to the double flower locus with no recombination events observed. Hence, these markers have the potential for application in the positional analysis of the double flower locus and, ultimately, may contribute towards determining the genetic basis of flower type. [ABSTRACT FROM AUTHOR]

Key message: Site-directed mutagenesis of nitrate reductase genes using direct delivery of purified Cas9 protein preassembled with guide RNA produces mutations efficiently in Petunia × hybrida protoplast system. Abstract: The clustered, regularly interspaced, short palindromic repeat (CRISPR)-CRISPR associated endonuclease 9 (CRISPR/Cas9) system has been recently announced as a powerful molecular breeding tool for site-directed mutagenesis in higher plants. Here, we report a site-directed mutagenesis method targeting Petunia nitrate reductase ( NR) gene locus. This method could create mutations efficiently using direct delivery of purified Cas9 protein and single guide RNA (sgRNA) into protoplast cells. After transient introduction of RNA-guided endonuclease (RGEN) ribonucleoproteins (RNPs) with different sgRNAs targeting NR genes, mutagenesis at the targeted loci was detected by T7E1 assay and confirmed by targeted deep sequencing. T7E1 assay showed that RGEN RNPs induced site-specific mutations at frequencies ranging from 2.4 to 21 % at four different sites (NR1, 2, 4 and 6) in the PhNR gene locus with average mutation efficiency of 14.9 ± 2.2 %. Targeted deep DNA sequencing revealed mutation rates of 5.3-17.8 % with average mutation rate of 11.5 ± 2 % at the same NR gene target sites in DNA fragments of analyzed protoplast transfectants. Further analysis from targeted deep sequencing showed that the average ratio of deletion to insertion produced collectively by the four NR-RGEN target sites (NR1, 2, 4, and 6) was about 63:37. Our results demonstrated that direct delivery of RGEN RNPs into protoplast cells of Petunia can be exploited as an efficient tool for site-directed mutagenesis of genes or genome editing in plant systems. [ABSTRACT FROM AUTHOR]

The present study aimed to determine the role of transcription factors (bHLH and MYB) in enhancing anthocyanin production in Petunia ‘Mirage rose’. Initially, we optimized an Agrobacterium -mediated transformation protocol to over-express transcription factors ( B-Peru , mPAP1 , and B-Peru + mPAP1 ) in Petunia. Phosphinothricin (PPT) concentrations of 0.5, 1.0, and 1.5 mg l −1 were found to be ideal for the selection and regeneration of transformed shoots at different developmental stages. Clavamox (250 mg l −1 ) efficiently eliminated Agrobacterium after co-cultivation (2 days) and favored maximum shoot regeneration. In addition, incubation for 30 min in Agrobacterium suspension increased the number of transformed cells and resulted in improved regeneration in the selection medium. The transformed plants were successfully developed through a direct organogenesis system. The transformed plants were selected using BASTA ® and the presence of transgenes was assessed using PCR. Visible anthocyanin accumulation was evident only in plantlets (shoots, stem, leaves, and roots) carrying the gene combination B-Peru + mPAP1 . The expression of biosynthetic genes involved in the flavonoid pathway was analyzed using quantitative real-time PCR. Expression levels of PAL , CHS , CHI , F3H , DFR , and ANS were higher in the young and mature leaves of plants transformed with B-Peru + mPAP1 compared to those transformed with B-Peru , mPAP1, and/or non-transformed plants. Furthermore, the highest level of anthocyanin was recorded in the leaves, stem, and roots of plants transformed with B-Peru + mPAP1 . These results validate the combinatorial requirement of B-Peru and mPAP1 to enhance anthocyanin content in Petunia hybrida ‘Mirage rose’. [ABSTRACT FROM AUTHOR]

The contribution of carbon assimilation and allocation and of invertases to the stimulation of adventitious root formation in response to a dark pre-exposure of petunia cuttings was investigated, considering the rooting zone (stem base) and the shoot apex as competing sinks. Dark exposure had no effect on photosynthesis and dark respiration during the subsequent light period, but promoted dry matter partitioning to the roots. Under darkness, higher activities of cytosolic and vacuolar invertases were maintained in both tissues when compared to cuttings under light. This was partially associated with higher RNA levels of respective genes. However, activity of cell wall invertases and transcript levels of one cell wall invertase isogene increased specifically in the stem base during the first two days after cutting excision under both light and darkness. During five days after excision, RNA accumulation of four invertase genes indicated preferential expression in the stem base compared to the apex. Darkness shifted the balance of expression of one cytosolic and two vacuolar invertase genes towards the stem base. The results indicate that dark exposure before planting enhances the carbon sink competitiveness of the rooting zone and that expression and activity of invertases contribute to the shift in carbon allocation. [ABSTRACT FROM AUTHOR]

The aim of this study was to establish an efficient virus-induced gene silencing (VIGS) protocol for the gibberellin 2-oxidase gene ( GA 2 ox ) in Petunia hybrida ‘Fantasy Blue’ to measure the reduction in GA 2 ox transcript levels by quantitative RT-PCR (qRT-PCR) and to investigate the phenotypes of the infected plants. In vitro multiplied Petunia plants were subjected to VIGS using tobacco rattle virus vectors. An 838-bp fragment from the N. tabacum gene ( NtGA 2 ox ) was cloned in the TRV2 vector. Control plants were also infected with a TRV2 vector containing a fragment of the E. coli β-glucuronidase ( GUS ) gene as a nonsense sequence. The abundance of the GA 2 ox and cyclophylin (for normalization) transcripts was determined by qRT-PCR four weeks after inoculation. Shoot tips with the five youngest leaves were used. Stem lengths were measured weekly from the day of inoculation. After four weeks, significant increases in stem elongation were observed in GA 2 ox -TRV2-infected plants compared with GUS -TRV2-infected plants. In accordance with this observation, the normalized abundance of the GA 2 ox transcript in GA 2 ox -TRV2-infected plants was significantly reduced compared with GUS -TRV2-infected plants. [ABSTRACT FROM AUTHOR]

Background: Petunia is a model to study the process of adventitious root (AR) formation on leafy cuttings. Excision of cuttings leads to a transient increase in jasmonates, which is regarded as an early, transient and critical event for rooting. Here, the role of jasmonates in AR formation on petunia cuttings has been studied by a reverse genetic approach. Results: To reduce the endogenous levels of jasmonates, transgenic plants were generated expressing a Petunia hybrida ALLENE OXIDE CYCLASE (PhAOC)-RNAi construct. The transgenic plants exhibited strongly reduced PhAOC transcript and protein levels as well as diminished accumulation of cis-12-oxo-phytodienoic acid, jasmonic acid and jasmonoyl-isoleucine after wounding in comparison to wild type and empty vector expressing plants. Reduced levels of endogenous jasmonates resulted in formation of lower numbers of ARs. However, this effect was not accompanied by altered levels of auxin and aminocyclopropane carboxylate (ACC, precursor of ethylene) or by impaired auxin and ethylene-induced gene expression. Neither activity of cell-wall invertases nor accumulation of soluble sugars was altered by jasmonate deficiency. Conclusions: Diminished numbers of AR in JA-deficient cuttings suggest that jasmonates act as positive regulators of AR formation in petunia wild type. However, wound-induced rise in jasmonate levels in petunia wild type cuttings seems not to be causal for increased auxin and ethylene levels and for sink establishment. [ABSTRACT FROM AUTHOR]

Flowers present a complex display of signals to attract pollinators, including the emission of floral volatiles. Volatile emission is highly regulated, and many species restrict emissions to specific times of the day. This rhythmic emission of scent is regulated by the circadian clock; however, the mechanisms have remained unknown. In Petunia hybrida, volatile emissions are dominated by products of the floral volatile benzenoid/phenylpropanoid (FVBP) metabolic pathway. Here we demonstrate that the circadian clock gene P. hybrida LATE ELONGATED HYPOCOTYL (LHY; PhLHY) regulates the daily expression patterns of the FVBP pathway genes and floral volatile production. PhLHY expression peaks in the morning, antiphasic to the expression of P. hybrida GIGANTEA (PhGI), the master scent regulator ODORANT1 (ODO1), and many other evening-expressed FVBP genes. Overexpression phenotypes of PhLHY in Arabidopsis caused an arrhythmic clock phenotype, which resembles those of LHY overexpressors. In Petunia, constitutive expression of PhLHY depressed the expression levels of PhGI, ODO1, evening-expressed FVBP pathway genes, and FVBP emission in flowers. Additionally, in the Petunia lines in which PhLHY expression was reduced, the timing of peak expression of PhGI, ODO1, and the FVBP pathway genes advanced to the morning. Moreover, PhLHY protein binds to cis-regulatory elements called evening elements that exist in promoters of ODO1 and other FVBP genes. Thus, our results imply that PhLHY directly sets the timing of floral volatile emission by restricting the expression of ODO1 and other FVBP genes to the evening in Petunia. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhiza (AM) is a mutual symbiosis that involves a complex symbiotic interface over which nutrients are exchanged between the plant host and the AM fungus. Dozens of genes in the host are required for the establishment and functioning of the interaction, among them nutrient transporters that mediate the uptake of mineral nutrients delivered by the fungal arbuscules. We have isolated in a genetic mutant screen a petunia (Petunia hybrida) GIBBERELLIC ACID INSENSITIVE, REPRESSOR of GIBBERELLIC ACID INSENSITIVE, and SCARECROW (GRAS)-type transcription factor, ATYPICAL ARBUSCULE (ATA), that acts as the central regulator of AM-related genes and is required for the morphogenesis of arbuscules. Forced mycorrhizal inoculations from neighboring wild-type plants revealed an additional role of ATA in restricting mycorrhizal colonization of the root meristem. The lack of ATA, which represents the ortholog of REQUIRED FOR ARBUSCULAR MYCORRHIZA1 in Medicago truncatula, renders the interaction completely ineffective, hence demonstrating the central role of AM-related genes for arbuscule development and function. [ABSTRACT FROM AUTHOR]

Cultivation of chilling-tolerant ornamental crops at lower temperature could reduce the energy demands of heated greenhouses. To provide a better understanding of how sub-optimal temperatures (12°C vs. 16°C) affect growth of the sensitive Petunia hybrida cultivar 'SweetSunshine Williams', the transcriptome, carbohydrate metabolism, and phytohormone homeostasis were monitored in aerial plant parts over 4 weeks by use of a microarray, enzymatic assays and GC-MS/MS. The data revealed three consecutive phases of chilling response. The first days were marked by a strong accumulation of sugars, particularly in source leaves, preferential up-regulation of genes in the same tissue and down-regulation of several genes in the shoot apex, especially those involved in the abiotic stress response. The midterm phase featured a partial normalization of carbohydrate levels and gene expression. After 3 weeks of chilling exposure, a new stabilized balance was established. Reduced hexose levels in the shoot apex, reduced ratios of sugar levels between the apex and source leaves and a higher apical sucrose/hexose ratio, associated with decreased activity and expression of cell wall invertase, indicate that prolonged chilling induced sugar accumulation in source leaves at the expense of reduced sugar transport to and reduced sucrose utilization in the shoot. This was associated with reduced levels of indole-3-acetic acid and abscisic acid in the apex and high numbers of differentially, particularly up-regulated genes, especially in the source leaves, including those regulating histones, ethylene action, transcription factors, and a jasmonate-ZIM-domain protein. Transcripts of one Jumonji C domain containing protein and one expansin accumulated in source leaves throughout the chilling period. The results reveal a dynamic and complex disturbance of plant function in response to mild chilling, opening new perspectives for the comparative analysis of differently tolerant cultivars. [ABSTRACT FROM AUTHOR]

Intracellular pH homeostasis is essential for all living cells. In plants, pH is usually maintained by three structurally distinct and differentially localized types of proton pump: P-type H+- ATPases in the plasma membrane, and multimeric vacuolar-type H+- ATPases (V- ATPases) and vacuolar H+-pyrophosphatases (H+- PPases) in endomembranes. Here, we show that reduced accumulation of proanthocyanidins ( PAs) and hence the diminished brown seed coloration found in the Arabidopsis thaliana mutant transparent testa 13 ( tt13) is caused by disruption of the gene encoding the P3A- ATPase AHA10. Identification of the gene encoded by the tt13 locus completes the molecular characterization of the classical set of transparent testa mutants. Cells of the tt13 seed coat endothelium do not contain PA-filled central vacuoles as observed in the wild-type. tt13 phenocopies tt12, a mutant that is defective in vacuolar import of the PA precursor epicatechin. Our data show that vacuolar loading with PA precursors depends on TT13. Consistent with the tt13 phenotype, but in contrast to other isoforms of P-type H+- ATPases, TT13 localizes to the tonoplast. PA accumulation in tt13 is partially restored by expression of the tonoplast localized H+- PPase VHP1. Our findings indicate that the P3A- ATPase TT13 functions as a proton pump in the tonoplast of seed coat endothelium cells, and generates the driving force for TT12-mediated transport of PA precursors to the vacuole. [ABSTRACT FROM AUTHOR]

Key message: Highly tolerant herbicide-resistant transgenic rice was developed by expressing codon-modified synthetic CP4 - EPSPS . The transformants could tolerate up to 1 % commercial glyphosate and has the potential to be used for DSR (direct-seeded rice). Abstract: Weed infestation is one of the major biotic stress factors that is responsible for yield loss in direct-seeded rice (DSR). Herbicide-resistant rice has potential to improve the efficiency of weed management under DSR. Hence, the popular indica rice cultivar IR64, was genetically modified using Agrobacterium-mediated transformation with a codon-optimized CP4- EPSPS (5-enolpyruvylshikimate-3-phosphate synthase) gene, with N-terminal chloroplast targeting peptide from Petunia hybrida. Integration of the transgenes in the selected rice plants was confirmed by Southern hybridization and expression by Northern and herbicide tolerance assays. Transgenic plants showed EPSPS enzyme activity even at high concentrations of glyphosate, compared to untransformed control plants. T, T and T lines were tested by herbicide bioassay and it was confirmed that the transgenic rice could tolerate up to 1 % of commercial Roundup, which is five times more in dose used to kill weeds under field condition. All together, the transgenic rice plants developed in the present study could be used efficiently to overcome weed menace. [ABSTRACT FROM AUTHOR]

We initiated this study to remediate indoor air pollution caused by volatile organic compounds by using plants. We isolated the glutathione-dependent formaldehyde dehydrogenase gene AtFALDH from Arabidopsis thaliana, inserted it into the expression vector pK2GW7, and introduced the gene into two purebred lines of Petunia hybrida to determine whether the gene would function in this ornamental plant. Seven shoots were regenerated from 248 explants cultured on the Murashige and Skoog basal medium. However, when the regenerated shoots were transferred to the second selection medium, only one shoot survived. The AtFALDH-transgenic T1 seeds were obtained from self-pollination of the single acclimated transgenic plant. These seeds produced 17 AtFALDH-transgenic T plants, 13 of which expressed the transgene, as determined by the PCR analysis. Among the 13 AtFALDH-transgenic T plants, 10 plants were confirmed by the Southern blot analysis to be identical to the transgenic plants and to possess three copies of the transgene. Furthermore, AtFALDH-transgenic T seeds were obtained from the self-pollination of the AtFALDH-transgenic T line, and the PCR analysis showed that 81 of the 105 AtFALDH-transgenic T plants exhibited the transgene. The transcription of the transgene was confirmed using the real-time PCR analysis in four of five plants that were selected randomly from the 81 AtFALDH-transgenic T plants. The AtFALDH-transgenic T plants removed 49.0 μg·m·cm leaf area of formaldehyde during a 5-h measurement period, as compared with only 38.9 μg·m·cm leaf area by the non-transgenic plants (a difference of 25.9%). Future work should focus on developing other AtFALDH-transgenic ornamental flora for use in the phytoremediation of formaldehyde gas. [ABSTRACT FROM AUTHOR]

Petunia hybrida is commonly cultivated for ornamental use in urban parks greening and street embellishment in China. In March 2022, 60% of P. hybrida plants cv. Wave Purple (n≈1800) from an ornamental plant nursery under natural conditions in Tianhe district (N 113°21'21", E 23°9'3.5"), Guangzhou, Guangdong Province, China, were affected with soft rot disease. The distribution of the disease was generally uniform. Infected plants initially exhibit small water-soaked lesions at the base of the stem, which then extended to the leaves. Eventually the diseased plant collapsed and died. Nine diseased plants were collected, and affected tissues cut into small fragments (5 × 5 mm), which were disinfested in 75% ethanol (30 s) and 2% sodium hypochlorite (60 s), followed by three rinses with sterile distilled water. The sterilized sections were macerated in 200 μl sterile water, and streaked on Luria-Bertani (LB) agar medium and incubated at 28°C for 48 h. Single colonies were restreaked three times to obtain purified isolation. Sixteen bacterial strains with similar morphology were isolated, and their colonies were yellowish white, round, and convex with smooth surfaces on LB agar plate. The representative strain BDQ1 was selected for further analyses and the 16S rDNA gene (GenBank Accession ON982467) were amplified using primer pair 27F/1492R, revealed above 99% sequence identity with some Pectobacterium brasiliense isolates (GenBank Accession Nos. CP046380(1421/1422), MN393966(1419/1422), and CP020350(1419/1422)) using BLASTn. A multilocus phylogenetic analysis by neighbor-joining method (1,000 bootstrap values) based on six housekeeping gene sequences of gyrA (GenBank Accession No. ON995454), icdA (ON995455), mdh (ON995456), mtlD (ON995457), proA (ON995458), and rpoS genes (ON995459) (Ma et al. 2007; Waleron et al., 2008). The results of phylogenetic analysis showed BDQ1 strain belong to the P. brasiliense clade. Pathogenicity tests were performed on ten healthy P. hybrida cv. Wave Purple plants by injecting 10 µl of bacterial suspensions of BDQ1 (10 8 CFU/ml) into the stems; another 10 healthy control plants were injected with 10 µl of sterile water. All plants were grown at 25-30°C and 60% humidity in natural light/dark cycle. After 3 d, all inoculated plants showed soft rot symptoms resembling to those observed in the nursery, while control plants remained healthy. Bacteria were successfully reisolated from the symptomatic tissues and identified to be P. brasiliense by PCR mentioned above. P. brasiliense is considered a very aggressive pathogen, which has been reported in Eurasia and Africa (Oulghazi et al. 2021). To our knowledge, this is the first report of P. brasiliense causing bacterial soft rot on P. hybrida in China. This pathogen may pose threat to P. hybrida production in area with warmand humid climate in China. The current study expands the known host range of P. brasiliense and helped raise attention on controlling pathogen spread.

Petunia hybrida is an important ornamental plant grown in many countries including India. It is a good model plant for the study of genetics and molecular biology. During a survey in 2013-2014, severe leaf curling was observed on most of the P. hybrida grown in the Sikar district, Rajasthan. The infected plants were analyzed for begomovirus infection by rolling circular amplification (RCA) and sequenced. Full length sequences confirmed the association of monopartite begomovirus with betasatellites. Phylogenetic analysis showed the highest percentage of identity with Chilli leaf curl virus (ChLCuV ) and therefore considered to be an isolate of ChLCuV. Recombination analysis showed that ChLCuV has broadened its host range by recombination process. To the best our knowledge, this is the first report of natural occurrence of ChLCuV on P. hybrida in India. [ABSTRACT FROM AUTHOR]

The establishment of alternative methods to chemical treatments for growth retardation and pathogen protection in ornamental plant production has become a major goal in recent breeding programmes. This study evaluates the effect of manipulating MAP kinase 4 nuclear substrate 1 ( MKS1) expression in Kalanchoë blossfeldiana and Petunia hybrida. The Arabidopsis thaliana MKS1 gene was overexpressed in both species via Agrobacterium-mediated transformation, resulting in dwarfed phenotypes and delayed flowering in both species and increased tolerance to Pseudomonas syringae pv. tomato in transgenic Petunia plants. The lengths of the stems and internodes were decreased, while the number of nodes in the transgenic plants was similar to that of the control plants in both species. The transgenic Kalanchoë flowers had an increased anthocyanin concentration, and the length of the inflorescence stem was decreased. The morphology of transgenic Petunia flowers was not altered. The results of the Pseudomonas syringae tolerance test showed that Petunia plants with one copy of the transgene reacted similarly to the nontransgenic control plants; however, plants with four copies of the transgene exhibited considerably higher tolerance to bacterial attack. Transgene integration and expression was determined by Southern blot hybridization and RT- PCR analyses. MKS1 in wild-type Petunia plants was down-regulated through a virus-induced gene silencing ( VIGS) method using tobacco rattle virus vectors. There were no significant phenotypic differences between the plants with silenced MKS1 genes and the controls. The relative concentration of the MKS1 transcript in VIGS-treated plants was estimated by quantitative RT- PCR. [ABSTRACT FROM AUTHOR]

Bedding plants are considered to be a very important element of the landscape for their variety of colours. Petunia is one of the most important bedding plants in urban landscape. According to recent droughts, determining the amount of irrigation and the selection of resistant varieties are necessary. In this study, the effect of drought stress was tested on some characteristics of three petunias. The two cultivars and one of the species of Petunia were Petunia hybrida "Explorer", Petunia hybrida "Carnival" and Petunia violacea, respectively. Irrigation treatments based on ET-HS model water requirement included S1 (100% irrigation), S2 (75% irrigation) and S3 (50% irrigation). The results showed that drought stress affected the morphological and physiological properties of Petunia plants. With increase in stress, the number of primary branches, flower diameter and canopy were reduced. Fifty per cent level significantly reduced the apparent factors in comparison to 75 and 100%. In severe stress, canopy of the Explorer was more affected in comparison with the two others, and showed the greatest sensitivity to drought stress. The flower's diameter of Violacea in S3 had the largest decrease compared to the other two varieties. The results showed that the root length increased with increase in stress levels for the availability of moisture. The highest root increase was observed in the level of S3. The drought stress affected total chlorophyll and proline content. Water stress reduced plant chlorophyll. The total chlorophyll in the three irrigation levels was significant for the Explorer and Violacea. The amount of amino acid proline increased with low irrigation levels. Only in Carnival, 50% had significant difference with two other treatments. So, the treatment of 75% ET-HS was recommended for saving in the use of water to keep up growth factors. [ABSTRACT FROM AUTHOR]