Cleome Hassleriana Research Articles

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Orychophragmus violaceus in China

Orychophragmus violaceus is an annual or perennial herb in the Brassicaceae family. It is widely planted in China and used as an ornamental and green manure plant (Luo et al. 2022). In September 2022, a survey conducted in a 600 m2 garden in Lanzhou (36°06′N, 103°43′E) found that over 70% of O. violaceus plants were infected with powdery mildew, with 80% of the leaf area on the upper surface of infected leaves was infected. The white colonies on the upper surface of the leaves gradually expanded, thickened, and spread to cover the stem surface. In severe cases, entire foliage withered and the plants died. Fungal structures were taken from the leaves with adhesive tape and placed in sterile water for microscopic observation. The conidiophores were upright, cylindrical, composed of 3 to 4 cells, and measured 92.3 ± 12.9 × 9.2 ± 0.6 μm (n=30). Conidial pedicels had 21.6 ± 3.4 μm (n=50) long cylindrical podocytes. Monoconidia were cylindrical or oval in shape, 32.9 ± 6.1 μm long and 15.1 ± 2.1 μm wide (n=80). Conidia lacked an obvious cellulose body. The bud tubes formed from the end of conidia, and papillary appressoria developed on the epiphytic mycelia. Based on these morphological characteristics, the pathogen was initially identified as Erysiphe cruciferarum (Braun et al. 2012). To validate the identity, the internal transcribed spacer (ITS) region of an isolate EYL was amplified by PCR and sequenced using both ITS1/ITS4 and ITS5/PM6 primers (Takamatsu et al. 2001). The resulting sequences were deposited at GenBank (accession nos: OR437967 and OR437969). The ITS sequence of the isolate EYL (OR437967) is 99% (451/453) identical to E. cruciferarum (KP730001) on Brassica napus in China and that of the isolate EYL (OR437969) is 100% (509/509) identical to E. cruciferarum (KM260718) on B. juncea in Vietnam. Pathogenicity experiments were performed on six-week-old plants with an average of 10 ± 0.8 leaves. In the inoculated group, five healthy plants were inoculated by gently pressing the upper surface of diseased leaves against the upper surface of leaves of healthy plants for about 5 to 10 seconds. In the control group, the leaves of five healthy plants were treated with asymptomatic using the same method as described above. The plants were maintained in a greenhouse set at 25℃, 14-h photoperiod, and ≥ 70% humidity. After 13 days, all inoculated plants showed symptoms of powdery mildew, while the plants in the control group had no symptoms. The fungus on the inoculated plant was re-isolated and identified as E. cruciferarum based on its morphological characteristics and ITS sequence. Powdery mildew caused by E. cruciferarum has been reported on Cleome hassleriana in Italy and B. juncea in Australia (Garibaldi et al. 2009; Kaur et al. 2008). To our knowledge, this is the first time that powdery mildew caused by E. cruciferarum have been reported on O. violaceus in China. This disease poses a potential threat to the quality and yield of O. violaceus plants, which may warrant the development of preventative and management strategies in the future.

Analysis of Carica papaya Informs Lineage-Specific Evolution of the Aquaporin (AQP) Family in Brassicales.

Aquaporins (AQPs), a type of intrinsic membrane proteins that transport water and small solutes across biological membranes, play crucial roles in plant growth and development. This study presents a first genome-wide identification and comparative analysis of the AQP gene family in papaya (Carica papaya L.), an economically and nutritionally important fruit tree of tropical and subtropical regions. A total of 29 CpAQP genes were identified, which represent five subfamilies, i.e., nine plasma intrinsic membrane proteins (PIPs), eight tonoplast intrinsic proteins (TIPs), seven NOD26-like intrinsic proteins (NIPs), two X intrinsic proteins (XIPs), and three small basic intrinsic proteins (SIPs). Although the family is smaller than the 35 members reported in Arabidopsis, it is highly diverse, and the presence of CpXIP genes as well as orthologs in Moringa oleifera and Bretschneidera sinensis implies that the complete loss of the XIP subfamily in Arabidopsis is lineage-specific, sometime after its split with papaya but before Brassicaceae-Cleomaceae divergence. Reciprocal best hit-based sequence comparison of 530 AQPs and synteny analyses revealed that CpAQP genes belong to 29 out of 61 identified orthogroups, and lineage-specific evolution was frequently observed in Brassicales. Significantly, the well-characterized NIP3 group was completely lost; lineage-specific loss of the NIP8 group in Brassicaceae occurred sometime before the divergence with Cleomaceae, and lineage-specific loss of NIP2 and SIP3 groups in Brassicaceae occurred sometime after the split with Cleomaceae. In contrast to a predominant role of recent whole-genome duplications (WGDs) on the family expansion in B. sinensis, Tarenaya hassleriana, and Brassicaceae plants, no recent AQP repeats were identified in papaya, and ancient WGD repeats are mainly confined to the PIP subfamily. Subfamily even group-specific evolution was uncovered via comparing exon-intron structures, conserved motifs, the aromatic/arginine selectivity filter, and gene expression profiles. Moreover, down-regulation during fruit ripening and expression divergence of duplicated CpAQP genes were frequently observed in papaya. These findings will not only improve our knowledge on lineage-specific family evolution in Brassicales, but also provide valuable information for further studies of AQP genes in papaya and species beyond.

First report of powdery mildew caused by Erysiphe cruciferarum on spider flower (Tarenaya hassleriana) in China.

Spider flower (Tarenaya (Cleome) hassleriana (Chodat) Iltis, Cleomaceae) is an excellent ornamental landscape plant and has an extensive flowering period, and therefore, plays an important role in horticulture (Parma et al. 2022). In May 2020 and April 2021, severe powdery mildew symptoms were observed on spider flower plants in a public garden (22.35°N and 113.56°E) in Shenzhen, China. Approximately 60 % of the plants were infected, and the adaxial surface of diseased leaves were covered with irregular white patches, which developed on tender to old leaves. In severe infections, drying and premature defoliation of infected leaves were observed. Microscopic examinations of mycelia showed irregularly lobed hyphal appressoria. Conidiophores (n = 30) were straight, unbranched, 65.65-92.11 μm long, and consisted of two to three cells. Conidia were formed singly on the top of conidiophores, cylindrical to oblong, 32.15-42.60 × 14.88-18.43 μm (mean 38.26 × 16.89, n = 50), and without distinct fibrosin bodies. Chasmothecia were not observed. The internal transcribed spacer (ITS) region and 28S rDNA was amplified using the primer sets ITS1/ITS5 and NL1/NL4, respectively. The representative sequences of ITS and 28S rDNA (GenBank accession nos.: MW879365 for ITS and MW879435 for 28S rDNA) analyzed by BLASTN search and showed 100 % identity with the sequences from Erysiphe cruciferarum found in GenBank (accession nos.: LC009943 for ITS and MF192846 for 28S rDNA). Phylogenetic analyses were conducted for further confirmation by using the combined sequences of ITS and 28S rDNA and indicated that the isolate ZDH046 grouped in a clade with isolates of E. cruciferarum (Figure S2). Based on morphological and molecular characteristics, this fungus was identified as E. cruciferarum (Braun and Cook, 2012). Koch's postulates were confirmed by gently pressing conidia from diseased leaves onto 30 leaves of healthy spider flower plants. After incubating for 10 d in a greenhouse (25 ℃ and 75 % relative humidity), similar symptoms to the diseased plants appeared on all inoculated leaves, whereas control leaves remained symptomless. Powdery mildew caused by E. cruciferarum on T. hassleriana has so far only been reported from France (Ale-Agha et al. 2008), Germany (Jage et al. 2010), Italy (Garibaldi et al. 2009), and New Zealand (Pennycook 1989, E. polygoni). To our knowledge, this is the first report of E. cruciferarum causing powdery mildew on T. hassleriana in China. This finding expands the known host range of E. cruciferarum in China and indicates a potential threat to plantations of T. hassleriana in China.

Integrated global analysis in spider flowers illuminates features underlying the evolution and maintenance of C4 photosynthesis.

The carbon concentrating mechanism-C4 photosynthesis-represents a classic example of convergent evolution, but how this important trait originated and evolved remains largely enigmatic. The spider flower Gynandropsis gynandra is a valuable leafy vegetable crop and medicinal plant that has also been recognized as a C4 model species. Here we present a high-quality chromosome-scale annotated genome assembly of G. gynandra through a combination of Oxford Nanopore Technology (ONT), HiFi and Hi-C technology. The 17 super-scaffolds cover 98.66% of the estimated genome (997.61Mb), with a contig N50 of 11.43Mb and a scaffold N50 of 51.02Mb. Repetitive elements occupy up to 71.91% of its genome, and over half are long terminal repeat retrotransposons (LTR-RTs) derived from recent bursts, contributing to genome size expansion. Strikingly, LTR-RT explosion also played a critical role in C4 evolution by altering expression features of photosynthesis-associated genes via preferential insertion in promoters. Integrated multiomics analyses of G. gynandra and the ornamental horticulture C3 relative Tarenaya hassleriana reveal that species-specific whole-genome duplication, gene family expansion, recent LTR-RT amplification, and more recent tandem duplication events have all facilitated the evolution of C4 photosynthesis, revealing uniqueness of C4 evolution in the Cleome genus. Moreover, high leaf vein density and heat stress resilience are associated with shifted gene expression patterns. The mode of C3-to-C4 transition found here yields new insights into evolutionary convergence of a complex plant trait. The availability of this reference-grade genomic resource makes G. gynandra an ideal model system facilitating efforts toward C4-aimed crop engineering.

Systematic approaches to C-lignin engineering in Medicago truncatula

BackgroundC-lignin is a homopolymer of caffeyl alcohol present in the seed coats of a variety of plant species including vanilla orchid, various cacti, and the ornamental plant Cleome hassleriana. Because of its unique chemical and physical properties, there is considerable interest in engineering C-lignin into the cell walls of bioenergy crops as a high-value co-product of bioprocessing. We have used information from a transcriptomic analysis of developing C. hassleriana seed coats to suggest strategies for engineering C-lignin in a heterologous system, using hairy roots of the model legume Medicago truncatula.ResultsWe systematically tested strategies for C-lignin engineering using a combination of gene overexpression and RNAi-mediated knockdown in the caffeic acid/5-hydroxy coniferaldehyde 3/5-O-methyltransferase (comt) mutant background, monitoring the outcomes by analysis of lignin composition and profiling of monolignol pathway metabolites. In all cases, C-lignin accumulation required strong down-regulation of caffeoyl CoA 3-O-methyltransferase (CCoAOMT) paired with loss of function of COMT. Overexpression of the Selaginella moellendorffii ferulate 5-hydroxylase (SmF5H) gene in comt mutant hairy roots resulted in lines that unexpectedly accumulated high levels of S-lignin.ConclusionC-Lignin accumulation of up to 15% of total lignin in lines with the greatest reduction in CCoAOMT expression required the strong down-regulation of both COMT and CCoAOMT, but did not require expression of a heterologous laccase, cinnamyl alcohol dehydrogenase (CAD) or cinnamoyl CoA reductase (CCR) with preference for 3,4-dihydroxy-substituted substrates in M. truncatula hairy roots. Cell wall fractionation studies suggested that the engineered C-units are not present in a heteropolymer with the bulk of the G-lignin.

The Gynandropsis gynandra genome provides insights into whole-genome duplications and the evolution of C4 photosynthesis in Cleomaceae.

Gynandropsis gynandra (Cleomaceae) is a cosmopolitan leafy vegetable and medicinal plant, which has also been used as a model to study C4 photosynthesis due to its evolutionary proximity to C3 Arabidopsis (Arabidopsis thaliana). Here, we present the genome sequence of G. gynandra, anchored onto 17 main pseudomolecules with a total length of 740 Mb, an N50 of 42 Mb and 30,933 well-supported gene models. The G. gynandra genome and previously released genomes of C3 relatives in the Cleomaceae and Brassicaceae make an excellent model for studying the role of genome evolution in the transition from C3 to C4 photosynthesis. Our analyses revealed that G. gynandra and its C3 relative Tarenaya hassleriana shared a whole-genome duplication event (Gg-α), then an addition of a third genome (Th-α, +1×) took place in T. hassleriana but not in G. gynandra. Analysis of syntenic copy number of C4 photosynthesis-related gene families indicates that G. gynandra generally retained more duplicated copies of these genes than C3T. hassleriana, and also that the G. gynandra C4 genes might have been under positive selection pressure. Both whole-genome and single-gene duplication were found to contribute to the expansion of the aforementioned gene families in G. gynandra. Collectively, this study enhances our understanding of the polyploidy history, gene duplication and retention, as well as their impact on the evolution of C4 photosynthesis in Cleomaceae.

Genome-Wide Analysis of Lipoxygenase (LOX) Genes in Angiosperms

Lipoxygenases (LOXs) are enzymes that catalyze the addition of an oxygen molecule to unsaturated fatty acids, thus forming hydroperoxides. In plants, these enzymes are encoded by a multigene family found in several organs with varying activity patterns, by which they are classified as LOX9 or LOX13. They are involved in several physiological functions, such as growth, fruit development, and plant defense. Despite several studies on genes of the LOX family in plants, most studies are restricted to a single species or a few closely related species. This study aimed to analyze the diversity, evolution, and expression of LOX genes in angiosperm species. We identified 247 LOX genes among 23 species of angiosperms and basal plants. Phylogenetic analyses identified clades supporting LOX13 and two main clades for LOX9: LOX9_A and LOX9_B. Eudicot species such as Tarenaya hassleriana, Capsella rubella, and Arabidopsis thaliana did not present LOX9_B genes; however, LOX9_B was present in all monocots used in this study. We identified that there were potential new subcellular localization patterns and conserved residues of oxidation for LOX9 and LOX13 yet unexplored. In summary, our study provides a basis for the further functional and evolutionary study of lipoxygenases in angiosperms.

Dormancy and germination characteristics of Tarenaya hassleriana (Cleomaceae) seeds

Abstract: Elucidating the physiological and ecological mechanisms of seed dormancy and germination is of great significance for species conservation and the application of plant resources. Based on Baskin and Baskin’s classification system for seed dormancy, the cause of dormancy in Tarenaya hassleriana (Cleomaceae) seeds was studied using alternating temperature, cold moist stratification, dry storage, and GA3 soaking treatment. The results indicated that fresh mature T. hassleriana seeds had a combinational dormancy, including a physical dormancy and a type 2 non-deep physiological dormancy, and were photoblastic, with an optimal germination temperature of 35°C. In addition, fresh mature T. hassleriana seeds may be efficiently released from dormancy and promoted to germinate by an alternating temperature of 20 °C/30 °C, cold moist stratification, and cold moist stratification following dry storage. Furthermore, GA3 soaking treatment could also promote dormancy release and subsequent germination at 35 °C, and dry storage treatment could promote dormancy release and subsequent germination at 5-15 °C. These results also suggested that there were complex cross-talks among phytohormone, osmotic potential, and the temperature signaling regulatory pathways during dormancy release and germination of T. hassleriana seeds, which deserve further study.

The Capparis spinosa var. herbacea genome provides the first genomic instrument for a diversity and evolution study of the Capparaceae family.

The caper bush Capparis spinosa L., one of the most economically important species of Capparaceae, is a xerophytic shrub that is well adapted to drought and harsh environments. However, genetic studies on this species are limited because of the lack of its reference genome. We sequenced and assembled the Capparis spinosa var. herbacea (Willd.) genome using data obtained from the combination of PacBio circular consensus sequencing and high-throughput chromosome conformation capture. The final genome assembly was approximately 274.53 Mb (contig N50 length of 9.36 Mb, scaffold N50 of 15.15 Mb), 99.23% of which was assigned to 21 chromosomes. In the whole-genome sequence, tandem repeats accounted for 19.28%, and transposable element sequences accounted for 43.98%. The proportion of tandem repeats in the C. spinosa var. herbacea genome was much higher than the average of 8.55% in plant genomes. A total of 21,577 protein-coding genes were predicted, with 98.82% being functionally annotated. The result of species divergence times showed that C. spinosa var. herbacea and Tarenaya hassleriana separated from a common ancestor 43.31 million years ago. This study reported a high-quality reference genome assembly and genome features for the Capparaceae family. The assembled C. spinosa var. herbacea genome might provide a system for studying the diversity, speciation, and evolution of this family and serve as an important resource for understanding the mechanism of drought and high-temperature resistance.

Characterization of a putative tropinone reductase from Tarenaya hassleriana with a broad substrate specificity.

A novel short-chain alcohol dehydrogenase from Tarenaya hassleriana labeled as putative tropinone reductase was heterologously expressed in Escherichia coli. Purified recombinant protein had molecular weight of approximately 30kDa on 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis. T. hassleriana tropinone reductase-like enzyme (ThTRL) had not detected oxidative activity. The optimum pH for enzyme activity of ThTRL was weakly acidic (pH 5.0). 50°C was the optimum temperature for ThTRL. The highest catalytic efficiency and substrate affinity for recombinant ThTRL were observed with (+)-camphorquinone (kcat /Km =814.3s-1 mM-1 , Km =44.25μM). ThTRL exhibited a broad substrate specificity and reduced various carbonyl compounds, including small lipophilic aldehydes and ketones, terpene ketones, and their structural analogs.

The complete chloroplast genome sequence of Gynandropsis gynandra (Cleomaceae)

Gynandropsis gynandra (L.) Briquet is a monoecious herb species in the family Cleomaceae. It is an important commercial crop with medicinal and nutritional values. Here, we sequenced, assembled, and analyzed the complete chloroplast genome of G. gynandra. The circular genome is 158,152 bp in size, consisting of two copies of inverted repeat (IR) regions of 26,181 bp, one large single-copy (LSC) region of 87,242 bp, and one small single-copy (SSC) region of 18,548 bp. The overall GC content was 35.81%. A total of 131 genes were annotated, including 37 tRNA genes, 87 protein-coding genes, and seven rRNA genes. Phylogenetic analysis based on 10 chloroplast genome sequences indicated that G. gynandra was more closely related to Tarenaya hassleriana.

Correction to: Cleome hassleriana plants fully support the development and reproduction of Nesidiocoris tenuis

Correction to: Cleome hassleriana plants fully support the development and reproduction of Nesidiocoris tenuis

Tracking the movement of Nesidiocoris tenuis among banker plants and crops in a tomato greenhouse by DNA markers of host plants

The zoophytophagous predator, Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), is an important biological control agent. To maintain this insect, several non-crop host plants are used as banker plants in greenhouse crop systems. To optimize the efficiency of the predator-banker plant interaction, it is necessary to investigate how individual predators move between banker plants and crops. However, the movement is difficult to quantify under field conditions. Therefore, we investigated the movement of N. tenuis between tomato plants (Solanum lycopersicum L., Solanales: Solanaceae) and three banker plants (Cleome hassleriana Chod., Brassicales: Cleomaceae; Sesamum indicum L., Lamiales: Pedaliaceae; and Verbena × hybrida Voss, Lamiales: Verbenaceae) in a greenhouse by conducting PCR using plant-species-specific primers. Laboratory analysis results showed that our molecular method could detect N. tenuis activity within a relatively short time (≤ 24 h). In addition, N. tenuis predation on a pest species was unlikely to result in false detection of plant DNA in the pest (suggesting that N. tenuis had been on the plants). Multiple plant species were detected in adult insects collected from the greenhouse plants, indicating that N. tenuis frequently moved across the mentioned plant species. The movement patterns of N. tenuis between plant species varied substantially based on the plant species from which they were collected, which suggested each of the plant species had different functions for N. tenuis. Our findings revealed that planting multiple host plants would stabilize the N. tenuis population in biological control programs.

Cleome hassleriana plants fully support the development and reproduction of Nesidiocoris tenuis

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is a zoophytophagous predator that feeds on plants as well as prey. Several non-crop host plant species have been used to maintain this mirid as a biological control agent in different crop systems. To evaluate the benefit of these non-crop host plants on biological control services, data on the life-history traits of N. tenuis on these plants are important as fundamental information. Herein, we studied the demographic growth parameters of N. tenuis reared on three alternative non-crop host plants (Cleome hassleriana Chod., Brassicales: Cleomaceae; Verbena × hybrida Voss, Lamiales: Verbenaceae; and Sesamum indicum L., Lamiales: Pedaliaceae) and one crop plant (tomato) in the absence of prey under laboratory conditions (25 ± 1 °C, 16:8 h L:D). The estimated intrinsic rate of increase in each plant was significantly greater in the following order: S. indicum (0.094) > C. hassleriana (0.074) > tomato (−0.002) > Verbena × hybrida (−0.060). The results indicated that C. hassleriana and S. indicum were able to fully support the development and reproduction of N. tenuis with nutrients derived from only its plant tissues, whereas Verbena × hybrida and tomato were not. Our findings revealed that C. hassleriana is a promising resource for the conservation or mass rearing of N. tenuis besides S. indicum.

Substrate Specificity of LACCASE8 Facilitates Polymerization of Caffeyl Alcohol for C-Lignin Biosynthesis in the Seed Coat of Cleome hassleriana.

Catechyl lignin (C-lignin) is a linear homopolymer of caffeyl alcohol found in the seed coats of diverse plant species. Its properties make it a natural source of carbon fibers and high-value chemicals, but the mechanism of in planta polymerization of caffeyl alcohol remains unclear. In the ornamental plant Cleome hassleriana, lignin biosynthesis in the seed coat switches from guaiacyl lignin to C-lignin at ∼12 d after pollination. Here we found that the transcript profile of the laccase gene ChLAC8 parallels the accumulation of C-lignin during seed coat development. Recombinant ChLAC8 oxidizes caffeyl and sinapyl alcohols, generating their corresponding dimers or trimers in vitro, but cannot oxidize coniferyl alcohol. We propose a basis for this substrate preference based on molecular modeling/docking experiments. Suppression of ChLAC8 expression led to significantly reduced C-lignin content in the seed coats of transgenic Cleome plants. Feeding of 13C-caffeyl alcohol to the Arabidopsis (Arabidopsis thaliana) caffeic acid o-methyltransferase mutant resulted in no incorporation of 13C into C-lignin, but expressing ChLAC8 in this genetic background led to appearance of C-lignin with >40% label incorporation. These results indicate that ChLAC8 is required for C-lignin polymerization and determines lignin composition when caffeyl alcohol is available.

Peronospora monardae, Hyaloperonospora daughtreyae and H. iberidis: new species associated with downy mildew diseases affecting ornamental plants in the United States

Species in the genera Hyaloperonospora and Peronospora (Oomycota, Peronosporaceae) are obligate biotrophic pathogens responsible for destructive downy mildew diseases of ornamental horticulture plants worldwide. Throughout the past decade, newly emergent downy mildew diseases have become increasingly prevalent, but often the identity of the pathogen is unknown or poorly defined. In this study we set out to identify the downy mildew pathogens infecting three widely grown ornamental plants: Agastache spp. (hyssops), Tarenaya hassleriana (syn. = Cleome hassleriana; spider-flower) and Monarda didyma (bee balm or bergamot). Phylogenetic analysis of the internal transcribed spacer rDNA and cox2 revealed two new species, which are described here as Peronospora monardae infecting both Monarda didyma and A. mexicana, and Hyaloperonospora daughtreyae infecting T. hassleriana. One sample of Peronospora collected from Agastache sp. ‘Bolero’ did not cluster with P. monardae, but its relationship to other species in the clade was not sufficiently resolved for taxonomic determination. Phylogenetic analysis also supported the combination of Peronospora iberidis, a pathogen of Iberis spp. (candytuft), into Hyaloperonospora. To assess intrasample ITS sequence variation from P. monardae, data were generated using high-throughput amplicon sequencing (HTAS). Multiple haplotypes were identified from the P. monardae samples, with less than 1% intrasample variation observed. From a core set of haplotypes shared across the HTAS the variant frequencies could not be completely explained by heterozygosity alone.

Enzymatic basis for C-lignin monomer biosynthesis in the seed coat of Cleome hassleriana.

C-lignin is a linear polymer of caffeyl alcohol, found in the seed coats of several exotic plant species, with promising properties for generation of carbon fibers and high value chemicals. In the ornamental plant Cleome hassleriana, guaiacyl (G) lignin is deposited in the seed coat for the first 6-12days after pollination, after which G-lignin deposition ceases and C-lignin accumulates, providing an excellent model system to study C-lignin biosynthesis. We performed RNA sequencing of seed coats harvested at 2-day intervals throughout development. Bioinformatic analysis identified a complete set of lignin biosynthesis genes for Cleome. Transcript analysis coupled with kinetic analysis of recombinant enzymes in Escherichia coli revealed that the switch to C-lignin formation was accompanied by down-regulation of transcripts encoding functional caffeoyl CoA- and caffeic acid 3-O-methyltransferases (CCoAOMT and COMT) and a form of cinnamyl alcohol dehydrogenase (ChCAD4) with preference for coniferaldehyde as substrate, and up-regulation of a form of CAD (ChCAD5) with preference for caffealdehyde. Based on these analyses, blockage of lignin monomer methylation by down-regulation of both O-methyltransferases (OMTs) and methionine synthase (for provision of C1 units) appears to be the major factor in diversion of flux to C-lignin in the Cleome seed coat, although the change in CAD specificity also contributes based on the reduction of C-lignin levels in transgenic Cleome with down-regulation of ChCAD5. Structure modeling and mutational analysis identified amino acid residues important for the preference of ChCAD5 for caffealdehyde.

PISTILLATA paralogs in Tarenaya hassleriana have diverged in interaction specificity

BackgroundFloral organs are specified by MADS-domain transcription factors that act in a combinatorial manner, as summarized in the (A)BCE model. However, this evolutionarily conserved model is in contrast to a remarkable amount of morphological diversity in flowers. One of the mechanisms suggested to contribute to this diversity is duplication of floral MADS-domain transcription factors. Although gene duplication is often followed by loss of one of the copies, sometimes both copies are retained. If both copies are retained they will initially be redundant, providing freedom for one of the paralogs to change function. Here, we examine the evolutionary fate and functional consequences of a transposition event at the base of the Brassicales that resulted in the duplication of the floral regulator PISTILLATA (PI), using Tarenaya hassleriana (Cleomaceae) as a model system.ResultsThe transposition of a genomic region containing a PI gene led to two paralogs which are located at different positions in the genome. The original PI copy is syntenic in position with most angiosperms, whereas the transposed copy is syntenic with the PI genes in Brassicaceae. The two PI paralogs of T. hassleriana have very similar expression patterns. However, they may have diverged in function, as only one of these PI proteins was able to act heterologously in the first whorl of A. thaliana flowers. We also observed differences in protein complex formation between the two paralogs, and the two paralogs exhibit subtle differences in DNA-binding specificity. Sequence analysis indicates that most of the protein sequence divergence between the two T. hassleriana paralogs emerged in a common ancestor of the Cleomaceae and the Brassicaceae.ConclusionsWe found that the PI paralogs in T. hassleriana have similar expression patterns, but may have diverged at the level of protein function. Data suggest that most protein sequence divergence occurred rapidly, prior to the origin of the Brassicaceae and Cleomaceae. It is tempting to speculate that the interaction specificities of the Brassicaceae-specific PI proteins are different compared to the PI found in other angiosperms. This could lead to PI regulating partly different genes in the Brassicaceae, and ultimately might result in change floral in morphology.

Biological Potential of Extracts of Caatinga Plants in the Control of Alternaria alternata f. sp. citri in Citrus

In Brazil the Caatinga biome is formed by endemic species with numerous applications in medicine, cosmetics and agrochemicals. However, only 8% of the country’s plant species are chemically evaluated annually. Thus, the work aimed to determine the free amino acid composition and phenolic substances of Caatinga plant species extracts, their antioxidant activity and the potential use of these compounds in the control of A. alternata in citrus. Leaf extracts from fourteen native plant species were evaluated for free amino acid contents; total and individual polyphenols; total flavonoids and antifungal susceptibility test. The relationship between the contents of the compounds detected in each plant extract with its antioxidant capacity and antifungal activity, has not yet been fully clarified. However, it is a fact that the extract of Cleome hassleriana constitutes a source rich in free amino acids. It is also verified that the extracts of Mimosa tenuiflora and Caesalpinia ferrea are efficient alternatives in the control of Alternaria alternata in citrus, because they present similar results for this purpose, and in the evaluation of their compositions in free amino acids, phenolic substances and antioxidant activity.

English

The objective of this study was to determine the elicitor potential of plant extracts from Caatinga biome by enzyme activity and epidemiological components of Alternaria brown spot (Alternaria alternate f. spp. citri). These were prepared ethanolic, dichloromethanic, and aqueous extracts from 14 plants (Anadenanthera macrocarpa, Schinopsis brasiliensis, Maytenus rigida, Caesalpinia pyramidalis, C. ferrea, Peltophorum dubium, Capariscyn ophallophora, Ziziphus joazeiro, Mimosa hostilis, Momordica charantia, Erythrina velutina, Cleome hassleriana, Sideroxylum obtusifolium Spondias tuberosa) after dilution, (1mg/mL) they were sprayed on Citrus reticulate ‘Ponkan’seedlings and after 0, 24, 48, 72 and 96 h the leaves were collected for determination of polyphenol oxidase and peroxidase activity. For epidemiological disease components, leaves were collected 72 h after spraying, deposited on Petri dishes with moist paper, inoculated with a spore suspension of A. alternata f. spp. citri (2x105 conidia mL-1) and evaluated for 12 days initial and final severity, area below the progress curve of disease and protection. The extracts of A. macrocarpa and M. rigida potentiated the polyphenol oxidase and peroxidase activity which had great potential in the management of the disease, reducing the final severity and area under the disease progress curve, providing high levels of control. Key words: Citrus reticulata, alternaria brown spot, elicitor. &nbsp