Petunia Hybrida Research Articles

A novel glutathione S-transferase gene from sweetpotato, IbGSTF4, is involved in anthocyanin sequestration

Anthocyanins are synthesized by multi-enzyme complexes localized at the cytoplasmic surface of the endoplasmic reticulum (synthesis site), and transported to the destination site, the vacuole. Three mechanisms for the vacuolar accumulation of anthocyanin in plant species have been proposed. Previous studies have indicated that glutathione S-transferase (GST) genes from model and ornamental plants are involved in anthocyanin transportation. In the present study, an anthocyanin-related GST, IbGSTF4, was identified and characterized based on transcriptome results. Phylogenetic analysis revealed that IbGSTF4 was most closely correlated to PhAN9 and CkmGST3, the anthocyanin-related GST of Petunia hybrida and Cyclamen. Furthermore, the expression analysis revealed that IbGSTF4 is strongly expressed in pigmented tissues, when compared to green organs, which is in agreement to the ability to correlate with anthocyanin accumulation. A GST activity assay uncovered that the IbGST4 protein owned similar activities with the GST family. Furthermore, the molecular functional complementation of Arabidopsis thaliana mutant tt19 demonstrated that IbGSTF4 might play a vital role in the vacuole sequestration of anthocyanin in sweetpotato. Moreover, the dual luciferase assay revealed that the LUC driven by the promoter of IbGSTF4 could not be directly activated by IbMYB1, suggesting that the regulatory mechanism of anthocyanin accumulation and sequestration in sweetpotato was intricate.

Comparison of petunia and calibrachoa in carotenoid pigmentation of corollas

Petunia (Petunia hybrida) is an important ornamental plant with a wide range of corolla colors. Although pale-yellow-flowered cultivars, with a low amount of carotenoids in their corollas, are now available, no deep-yellow-flowered cultivars exist. To find why petunia cannot accumulate enough carotenoids to have deep-yellow flowers, we compared carotenoid profiles and expression of carotenoid metabolic genes between pale-yellow-flowered petunia and deep-yellow-flowered calibrachoa (Calibrachoa hybrida), a close relative. The carotenoid contents and the ratios of esterified xanthophylls to total xanthophylls in petunia corollas were significantly lower than those in calibrachoa, despite similar carotenoid components. A lower esterification rate of trans-xanthophylls than of cis-xanthophylls in petunia suggests that petunia xanthophyll esterase (XES) has low substrate specificity for trans-xanthophylls, which are more abundant than cis-xanthophylls in petunia corolla. The expression of genes encoding key enzymes of carotenoid biosynthesis was lower and that of a carotenoid catabolic gene was higher in petunia. XES expression was significantly lower in petunia. The results suggest that low biosynthetic activity, high cleavage activity, and low esterification activity cause low carotenoid accumulation in petunia corollas.

Identification and functional analysis of three new anthocyanin R2R3-MYB genes in Petunia.

We identified three novel members of the R2R3‐MYB clade of anthocyanin regulators in the genome of the purple flowering Petunia inflata S6 wild accession, and we called them ANTHOCYANIN SYNTHESIS REGULATOR (ASR). Two of these genes, ASR1 and ASR2, are inactivated by two different single base mutations in their coding sequence. All three of these genes are absent in the white flowering species P. axillaris N and P. parodii, in the red flowering P. exserta, and in several Petunia hybrida lines, including R27 and W115. P. violacea and other P. hybrida lines (M1, V30, and W59) instead harbor functional copies of the ASR genes. Comparative, functional and phylogenic analysis of anthocyanin R2R3‐MYB genes strongly suggest that the ASR genes cluster is a duplication of the genomic fragment containing the other three R2R3‐MYB genes with roles in pigmentation that were previously defined, the ANTHOCYANIN4‐DEEP PURPLE‐PURPLE HAZE (AN4‐DPL‐PHZ) cluster. An investigation of the genomic fragments containing anthocyanin MYBs in different Petunia accessions reveals that massive rearrangements have taken place, resulting in large differences in the regions surrounding these genes, even in closely related species. Yeast two‐hybrid assays showed that the ASR proteins can participate in the WMBW (WRKY, MYB, B‐HLH, and WDR) anthocyanin regulatory complex by interacting with the transcription factors AN1 and AN11. All three ASRs can induce anthocyanin synthesis when ectopically expressed in P. hybrida lines, but ASR1 appeared to be the most effective. The expression patterns of ASR1 and ASR2 cover several different petunia tissues with higher expression at early stages of bud development. In contrast, ASR3 is only weakly expressed in the stigma, ovary, and anther filaments. The characterization of these novel ASR MYB genes completes the picture of the MYB members of the petunia anthocyanin regulatory MBW complex and suggests possible mechanisms of the diversification of pigmentation patterns during plant evolution.

The chloroplast genome sequence of the ornamental plant Petunia hybrida

Petunia hybrida is a popular ornamental plant and a model for chloroplast research. A complete P. hybrida chloroplast genome sequence would advance phylogenetic studies in the Solanaceae sub-family Petunioideae and is essential for developing synthetic biology tools to study and manipulate chloroplast function for fundamental and industrial applications. Here we present the 156,575 bp P. hybrida chloroplast genome sequence. It is comprised of 87,083 bp large single copy and 18,630 bp small single copy regions separated by 25,431 bp inverted repeats. Seventy-nine proteins, 30 transfer-RNAs and four ribosomal RNA species are encoded by 113 unique genes. The results of phylogenetic analysis using complete Solanaceous chloroplast genomes are consistent with other data that supports an early split for the P. hybrida lineage away from the branch giving rise to groups containing major crops such as tobacco (Nicotianoideae) and potato (Solanoideae).

Cloning and Functional Verification of Genes Related to 2-Phenylethanol Biosynthesis in Rosa rugosa.

In China, Rosa rugosa is cultivated as a source of natural perfumes. Rose essential oil is known as “liquid gold”, given its high economic and health value. 2-phenylethanol accounts for more than 10% of the total mass fraction of the essential oil derived from R. rugosa. The regulatory mechanisms underlying 2-phenylethanol metabolism in R. rugosa, however, remain unclear. In this study, RrAAAT and RrPPDC1, two genes related to 2-phenylethanol synthesis, were cloned from R. rugosa. Expression analysis revealed that RrAAAT and RrPPDC1 were highly expressed in rose flowers in the full opening and withering stages, and in calyxes. The overexpression vectors of RrAADC, RrAAAT, and RrPPDC1 were established and transformed into Petunia hybrida via Agrobacterium-mediated genetic transformation. Results demonstrated that the overexpression of RrAADC and RrAAAT increased the 2-phenylethanol content of transgenic petunia flowers. The results of this study provide a basis for the introduction of genes related to 2-phenylethanol synthesis into roses to increase the 2-phenylethanol content of rose essential oil.

Overexpression of CONSTANS-like 16 enhances chlorophyll accumulation in petunia corollas

We have previously found that a gene closely related to Arabidopsis CONSTANS-like 16 (COL16) was coordinately expressed with chlorophyll content in chrysanthemum petals and leaves. Here, to elucidate whether COL16 is involved in the regulation of chlorophyll biosynthesis and accumulation, we analyzed the function of COL16 in petunia (Petunia hybrida). We identified three petunia COL16 homologs: PhCOL16a, PhCOL16b, and PhCOL16c. Expression patterns of all three homologs were associated with chlorophyll content, with lower levels in white corollas than in pale green corollas, and relatively high levels in leaves. The result suggests that PhCOL16 homologs are involved in chlorophyll accumulation. We introduced a PhCOL16a overexpression construct into petunia. The transgenic plants had pale green corollas with a higher chlorophyll content than wild-type plants. Expression of genes encoding key enzymes of chlorophyll biosynthesis was significantly higher in the transgenic plants than in the wild-type plants. The results indicate that PhCOL16 positively regulates chlorophyll biosynthesis.

Scanning Electron Microscopy (SEM) and Light Microscopy (LM)-based Palyno-morphological views of Solanaceae in Western Himalaya.

In this study, plants belonging to family Solanaceae growing in Western Himalaya region have been observed palynologically under Light Microscope and Scanning electron microscope. Present investigation comprises of 10 genera and 23 species, namely, Atropa acuminata, Capsicum decoraticus, Capsicum frutescens, Cestrum aurantiacum, Cestrum diurnum, Cestrum nocturnum, Datura alba, Datura innoxia, Datura stramonium, Hyoscymus niger, Lycopersicon esculentum, Nicotiana rustica, Nicotiana tabacum, Petunia alba, Petunia hybrida, Solanum erianthum, Solanum melongena, Solanum miniatum, Solanum pseudocapsicum, Solanum surratense, Solanum tuberosum, Withania coagulans, Withania somnifera. Solanaceae is a eurypalynous family. Grains are usually Tricolporate and Tetracolporate, radially symmetrical, isopolar, prolate-spheroidal to oblate-spheroidal to oblate-spheroidal to subprolate to per prolate or suboblate to oblate, size range: 8.55-72 μm, amb circular, semi-angular or subangular, aperture drop-type, labrum common-type, exine usually 2 μm thick, nexine 1-1.5 μm thick. Tectum usually psilate, sexine reticulate, granulate or striato-reticulate, with obscure pattern, sexine 1-2 μm thick, nexine 1-1.5 μm thick, and intine 0.5-1 μm thick. Most striking variation has been found in the shape class, aperture-type, and tectal surface. Based on these characters, taxonomic keys have been made for correct identification of members in Solanaceae. However, the grains of this family are usually tricolporate and have direct relationship with certain members of the family Scrophulariaceae. Palyno-morphological characters of family Solanaceae have been studied for the first time in Western Himalayan region of Pakistan. These palyno-morphological characters are significant for identification of the members of family Solanaceae.

Simulated microgravity and the antagonistic influence of strigolactone on plant nutrient uptake in low nutrient conditions

Human-assisted space exploration will require efficient methods of food production. Large-scale farming in presence of an Earth-like atmosphere in space faces two main challenges: plant yield in microgravity and plant nutrition in extraterrestrial soils, which are likely low in nutrients compared to terrestrial farm lands. We propose a plant-fungal symbiosis (i.e. mycorrhiza) as an efficient tool to increase plant biomass production in extraterrestrial environments. We tested the mycorrhization of Solanaceae on the model plant Petunia hybrida using the arbuscular mycorrhizal fungus Rhizophagus irregularis under simulated microgravity (s0-g) conditions obtained through a 3-D random positioning machine. Our results show that s0-g negatively affects mycorrhization and plant phosphate uptake by inhibiting hyphal elongation and secondary branching. However, in low nutrient conditions, the mycorrhiza can still support plant biomass production in s0-g when colonized plants have increased SL root exudation. Alternatively, s0-g in high nutrient conditions boosts tissue-specific cell division and cell expansion and overall plant size in Petunia, which has been reported for other plants species. Finally, we show that the SL mimic molecule rac-GR24 can still induce hyphal branching in vitro under simulated microgravity. Based on these results, we propose that in nutrient limited conditions strigolactone root exudation can challenge the negative microgravity effects on mycorrhization and therefore might play an important role in increasing the efficiency of future space farming.

Mammalian CYP2E1 gene triggered changes of relative ions fluxes, CaM content and genes expression profiles in Petunia hybrida cells to enhance resistance to formaldehyde

Cytochrome P450 CYP2E1, encoded by CYP2E1 gene, is mainly present in the mammal hepatocytes and plays important roles in metabolizing xenobiotic compounds. The CYP2E1-transgenic Petunia hybrida enhanced the resistance of Petunia against formaldehyde. In this study, we investigated the biochemical and physiological changes in CYP2E1-transgenic Petunia before and after formaldehyde stress. Non-invasive micro-test technology was applied to monitor the changes in fluxes of K+, H+ and Ca2+ ions. The changes in calmodulin (CaM) content were measured with enzyme-linked immunosorbent assay. The gene expression profiles were assayed with digital gene expression tag profiling. The steady efflux of K+ in leaf cells of CYP2E1-transgenic Petunia was higher whereas the steady efflux of H+ in leaf cells of CYP2E1-transgenic Petunia under formaldehyde stress were lower than those of the controls (wild-type and gus-transgenic Petunia). These results suggest that the capability of Petunia to resist formaldehyde stress is correlated with the steady K+ efflux rate. It could be possible that the enhanced expression of CYP2E1 greatly reduced the generation of H+ and the H+ efflux to reduce the damage to plant cells caused by oxidative stress under formaldehyde stress. Ca2+ in leaf cells of CYP2E1-transgenic Petunia exhibited efflux whereas Ca2+ in leaf cells of controls exhibited influx. CaM content in CYP2E1-transgenic Petunia was significantly higher than those in controls. Before and after formaldehyde stress, the differentially expressed sequence tags (ESTs) meeting ≥ two-fold difference, in wild-type Petunia, the up-regulated ESTs were 1344 while the down-regulated ESTs were 1516; in CYP2E1-transgenic Petunia, the up-regulated ESTs were 975 while the down-regulated ESTs were 638. Compared to those of the wild-type Petunia, after formaldehyde stress, both of up-regulated and down-regulated ESTs in CYP2E1-transgenic Petunia were significantly reduced. After formaldehyde stress, in CYP2E1-transgenic Petunia, the enzymes closely related to photosynthetic systems were all down-regulated. These results indicate that CYP2E1 can enhance the capability of Petunia to resist formaldehyde stress but it may not activate Calvin cycle during formaldehyde metabolism process.

The Floral C-Lineage Genes Trigger Nectary Development in Petunia and Arabidopsis

To attract insects, flowers produce nectar, an energy-rich substance secreted by specialized organs called nectaries. For Arabidopsis thaliana, a rosid species with stamen-associated nectaries, the floral B-, C-, and E-functions were proposed to redundantly regulate nectary development. Here, we investigated the molecular basis of carpel-associated nectary development in the asterid species petunia (Petunia hybrida). We show that its euAGAMOUS (euAG) and PLENA (PLE) C-lineage MADS box proteins are essential for nectary development, while their overexpression is sufficient to induce ectopic nectaries on sepals. Furthermore, we demonstrate that Arabidopsis nectary development also fully depends on euAG/PLE C-lineage genes. In turn, we show that petunia nectary development depends on two homologs of CRABS CLAW (CRC), a gene previously shown to be required for Arabidopsis nectary development, and demonstrate that CRC expression in both species depends on the members of both euAG/PLE C-sublineages. Therefore, petunia and Arabidopsis employ a similar molecular mechanism underlying nectary development, despite otherwise major differences in the evolutionary trajectory of their C-lineage genes, their distant phylogeny, and different nectary positioning. However, unlike in Arabidopsis, petunia nectary development is position independent within the flower. Finally, we show that the TARGET OF EAT-type BLIND ENHANCER and APETALA2-type REPRESSOR OF B-FUNCTION genes act as major regulators of nectary size.

Epigenetic regulation of dihydroflavonol reductase in petunia and sensitivity of chalcone synthase promoter to RNA dependent DNA methylation

Petal colour is an excellent marker to study regulation of dihydroflavonol 4-reductase (DfrA) and chalcone synthase (Chs) involved in plant pigment biosynthesis. Still, alternative regulation of genes without altering their primary DNA sequences is still developing. In this study, fragments of DfrA promoter and coding region were transformed and tested for activity in petunia ( Petunia hybrida ) severely methylated in the promoter. On the other hand, we examined if inverted repeat construct of ChsA promoter is sufficient to methylate homologous sequences to induce silencing in petunia. We report that W80 petunia lines having W4 constructs produced flowers with pink petals. Stunted growth, delayed maturation and patched yellow coloration of leaves were evident in V26 lines transformed with V2, though the plants did not yet flower by the end of the study period. However, all V26 lines with V4 produced flowers with purple petals. It was unexpected to note that W80 plant lines with V4 produced white flowers. The fact that W80 plant lines with W4 produced purple flowers suggests that both the transgene and DfrA promoter may have been active in a white petal plant. The results suggest that the promoter was active to drive the expression of pigmentation genes. Keywords: petunia, DNA methylation, Agrobacterium tumefaciens , chalcone synthase, dihydroflavonol 4-reductase

Regulation of Carotenoid Pigmentation in Corollas of Petunia

Petunia (Petunia hybrida) is an important ornamental plant, with corolla colors ranging widely from pink to red to purple, owing mainly to anthocyanins. Although there are no bright-yellow-flowered cultivars, some pale-yellow-flowered cultivars accumulate a small amount of carotenoids. To find a key regulatory step that controls carotenoid content in petunia corollas, we compared the expression of carotenoid metabolism genes and carotenoid composition in corollas of white-flowered and pale-yellow-flowered cultivars. Pale yellow corollas tended to have higher expression of biosynthesis genes. The most prominent result was the complete lack of carotenoid cleavage dioxygenase 4a (CCD4a) transcripts in pale yellow corollas. We found two insertions, one in the putative promoter region and the other in the coding region, of the genomic CCD4a sequence of a pale-yellow-flowered cultivar relative to that of a white-flowered cultivar. We consider this the main reason for the lack of CCD4a transcripts. The results suggest that pale yellow corollas have higher carotenoid biosynthesis activity and lower catabolism activity than white corollas. We propose that carotenoid content in petunia corollas is determined by the balance of the degradation and biosynthesis of carotenoids.

Morpho-physiological plant quality when biochar and vermicompost are used as growing media replacement in urban horticulture

Peat moss is the most used soilless substrate in the production of container plants in floriculture. Nevertheless, the drainage of peat bogs due to the peat extraction has increased the necessity of seeking products that could replace the peat that is used in plant production. Therefore, a comparative study was conducted to evaluate the effect of a biochar (B) - vermicompost (V) mixture, as a partial substitute for peat-based substrates, on the morpho-physiological characteristics of ornamental plants. Different blends containing B and V were compared to a baseline peat-based substrate (S) as control in the cultivation of two ornamental bedding plant species that are widely used in urban areas: geranium (Pelargonium peltatum) and petunia (Petunia hybrida). Plant growth and physiological parameters were assessed. Results showed that it is possible to grow container plants of these two species with commercial quality, using a peat-based substrate mixed with biochar and/or vermicompost (up to 30% V and 12% B). Plants in these substrates showed a similar or enhanced physiological response to those grown in the control using commercial peat-based substrate.

Effect of Different Carbon Sources on in Vitro Shoot Regeneration of Petunia Hybrid Hort. Vilm

Effect of Different Carbon Sources on in Vitro Shoot Regeneration of Petunia Hybrid Hort. Vilm

Overexpression of SbSKIP, A Pre-mRNA splicing factor from Sorghum bicolor, enhances root growth and drought tolerance in Petunia hybrida

Abstract Pre-mRNA splicing factors have been shown to have important roles in understanding the response of plants to various abiotic stresses. Different splicing factors might have different roles in plant stress responses. One splicer factor, skip (Sloan-Kettering retrovirus interacting protein), has been shown to play an important role in the tolerance of plants to various abiotic stresses although its mechanism of action is unknown. SbSKIP (Sorghum bicolor skip) encodes an RNA metabolism-related protein that could improve tobacco’s drought tolerance of tobacco. There is uncertainty how SbSKIP would act in other species and it effect on potential target genes. We found that overexpression of SbSKIP in Petunia hybrida could promote the growth of lateral roots and enhance drought tolerance. After withholding water for 14 d, SbSKIP plants grew better than WT (wild-type) plants; WT plants leaves were severely wilted and died, whereas transgenic plants were turgid after 17 d of drought treatment. Water stressed transgenic plants overexpressed SbSKIP, increased leaf proline synthesis and antioxidant defense enzyme activities, and decreased the accumulation of MDA. Furthermore, SbSKIP also regulated stress-induced gene expression under drought stress. These results suggest that overexpression of SbSKIP improves the tolerance of petunia to drought stress by enhancing antioxidant defense enzymes that decrease the content of cell membrane peroxidation, and by regulating the expression of stress-induced genes and the synthesis of proline.

Elimination of macro elements from inoculation and co-cultivation media enhances the efficiency of Agrobacterium-mediated transformation in Petunia.

In order to evaluate the effect of inoculation and co-cultivation media elements on transformation frequency in Petunia hybrida, modified MS media with different elements were tested on Alvan and Large Flower Alvan (LF Alvan), two local cultivars. Leaf explants of both cultivars were inoculated with Agrobacterium tumefaciens strain LBA4404 (pBI121) containing neomycin phosphotransferase (nptII) and an intron-containing β-glucuronidase (gus) genes. When medium lacking KH2PO4, NH4NO3, KNO3, and CaCl2 was used as inoculation and co-cultivation medium, a higher frequency of transformation for Alvan (22%) and LF Alvan (16%) was obtained. Kanamycin resistant plantlets were stained blue by GUS assay. Furthermore, polymerase chain reaction (PCR) analysis revealed the presence of both gus and nptII genes in all putative transformants. Finally, southern blot hybridization confirmed insertion of 1-4 copies of gus gene in transgenic plants.

Synthesis and inhibitory activity of mechanism-based 4-coumaroyl-CoA ligase inhibitors

4-Coumaroyl-CoA ligase (4CL) is ubiquitous in the plant kingdom, and plays a central role in the biosynthesis of phenylpropanoids such as lignins, flavonoids, and coumarins. 4CL catalyzes the formation of the coenzyme A thioester of cinnamates such as 4-coumaric, caffeic, and ferulic acids, and the regulatory position of 4CL in the phenylpropanoid pathway renders the enzyme an attractive target that controls the composition of phenylpropanoids in plants. In this study, we designed and synthesized mechanism-based inhibitors for 4CL in order to develop useful tools for the investigation of physiological functions of 4CL and chemical agents that modulate plant growth with the ultimate goal to produce plant biomass that exhibits features that are beneficial to humans. The acylsulfamide backbone of the inhibitors in this study was adopted as a mimic of the acyladenylate intermediates in the catalytic reaction of 4CL. These acylsulfamide inhibitors and the important synthetic intermediates were fully characterized using two-dimensional NMR spectroscopy. Five 4CL proteins with distinct substrate specificity from four plant species, i.e., Arabidopsis thaliana, Glycine max (soybean), Populus trichocarpa (poplar), and Petunia hybrida (petunia), were used to evaluate the inhibitory activity, and the half-maximum inhibitory concentration (IC50) of each acylsulfamide in the presence of 4-coumaric acid (100 µM) was determined as an index of inhibitory activity. The synthetic acylsulfamides used in this study inhibited the 4CLs with IC50 values ranging from 0.10 to 722 µM, and the IC50 values of the most potent inhibitors for each 4CL were 0.10–2.4 µM. The structure–activity relationship observed in this study revealed that both the presence and the structure of the acyl group of the synthetic inhibitors strongly affect the inhibitory activity, and indicates that 4CL recognizes the acylsulfamide inhibitors as acyladenylate mimics.

Lateral Root Development in Potato Is Mediated by Stu-mi164 Regulation of NAC Transcription Factor.

The NAC designation is derived from petunia (Petunia hybrida) gene NO APICAL MERISTEM (NAM) and Arabidopsis genes ATAF1/ATAF2 and CUP-SHAPED COTYLEDON2 (CUC2), which belongs to the family of plant-specific transcription factors (TFs), and plays important role in plant development processes, such as response to biotic and abiotic stress, and hormone signaling. MicroRNAs (miRNAs) are a class of small, non-coding endogenous RNAs which play versatile and significant role in plant stress response and development via negatively affecting gene expression at a post-transcriptional level. Here, we showed that Stu-mi164 had a complementary sequence in the CDS sequence of potato NAC TFs, and that NAC expression exhibited significant differences under osmotic stress. We measured expression levels of the Stu-mi164 target gene StNAC262 between control and PEG-treated plants using real-time PCR, and the results demonstrated that they had inverse relationship. We suggested that Stu-miR164 might drive overexpression of NAC gene under osmotic stress in potato. To confirm the regulation of NAC TFs by Stu-mi164, we developed transgenic plants, using Agrobacterium tumefaciens–mediated transformation, of the potato cultivars “Gannongshu 2” and “Kexin 3” overexpressing the Stu-mi164 or the TF StNAC262. Real-time PCR analysis of transgenic potato plants under osmotic (PEG) stress, showed that potato plants overexpressing Stu-mi164 had reduced expression of StNAC262 and their osmotic resistance decreased. Furthermore, these plants had low number of lateral roots although the same length as the control. Our findings support the regulatory role of Stu-miRNAs in controlling plant response to osmotic stress via StNAC262.

Comparison of Frankliniella fusca and Frankliniella occidentalis (Thysanoptera: Thripidae) as Vectors for a Peanut Strain of Tomato Spotted Wilt Orthotospovirus.

Tomato spotted wilt orthotospovirus (TSWV) is a major disease in peanut, Arachis hypogaea L., across peanut producing regions of the United States and elsewhere. Two thrips, Frankliniella fusca Hinds and Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), are considered important vectors of TSWV in peanut in the Southeast. We compared the efficiency of acquisition (by larvae) and transmission (adults) of both thrips species for TSWV (Texas peanut-strain) to leaf disks of peanut (Florunner), as well as to Impatiens walleriana Hook. f. (Dwarf White Baby) and Petunia hybrida Juss. 'Fire Chief' using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Both species were competent TSWV vectors in peanut and Impatiens, although F. fusca was the more efficient vector overall, i.e., virus acquisition and transmission rates for F. fusca averaged over several bioassays were 51.7 and 26.6%, respectively, compared with 20.0 and 15.3% for F. occidentalis. Neither species effectively transmitted this TSWV strain to Petunia (i.e., ≤3.6% transmission). We found statistically similar virus acquisition and transmission rates between both sexes for each species. We also detected no differences in TSWV-acquisition and transmission frequency between macropterous and brachypterous (short-wing) forms of F. fusca collected from a field population in south Texas. DAS-ELISA failed to detect low levels of TSWV in a few thrips that subsequently proved to be competent vectors.

Recent advances in flower color variation and patterning of Japanese morning glory and petunia.

The Japanese morning glory (Ipomoea nil) and petunia (Petunia hybrida), locally called “Asagao” and “Tsukubane-asagao”, respectively, are popular garden plants. They have been utilized as model plants for studying the genetic basis of floricultural traits, especially anthocyanin pigmentation in flower petals. In their long history of genetic studies, many mutations affecting flower pigmentation have been characterized, and both structural and regulatory genes for the anthocyanin biosynthesis pathway have been identified. In this review, we will summarize recent advances in the understanding of flower pigmentation in the two species with respect to flower hue and color patterning. Regarding flower hue, we will describe a novel enhancer of flavonoid production that controls the intensity of flower pigmentation, new aspects related to a flavonoid glucosyltransferase that has been known for a long time, and the regulatory mechanisms of vacuolar pH being a key determinant of red and blue coloration. On color patterning, we describe particular flower patterns regulated by epigenetic and RNA-silencing mechanisms. As high-quality whole genome sequences of the Japanese morning glory and petunia wild parents (P. axillaris and P. inflata, respectively) were published in 2016, further study on flower pigmentation will be accelerated.