Variegated Research Articles

Fine Mapping of BoVl Conferring the Variegated Leaf in Ornamental Kale (Brassica oleracea var. acephala)

Ornamental kale, as a burgeoning landscaping plant, is gaining popularity for its rich color patterns in leaf and cold tolerance. Leaf variegation endows ornamental kale with unique ornamental characters, and the mutants are ideal materials for exploring the formation mechanisms of variegated phenotype. Herein, we identified a novel variegated leaf kale mutant ‘JC007-2B’ with green margins and white centers. Morphological observations and physiological determinations of the green leaf stage (S1), albino stage (S2) and variegated leaf stage (S3) demonstrated that the chloroplast structure and photosynthetic pigment content in the white sectors (S3_C) of variegated leaves were abnormal. Genetic analysis revealed that a single dominant nuclear gene (BoVl) controlled the variegated leaf trait of ‘JC007-2B’, and three candidate genes for BoVl were fine-mapped to a 6.74 Kb interval on chromosome C03. Multiple sequence alignment among the green-leaf mapping parent ‘BS’, recombinant individuals, mutant parent ‘JC007-2B’ and its same originated DH line population established that the mutation sites in Bo3g002080 exhibited a complete consensus. Bo3g002080, homologous to Arabidopsis MED4, was identified as the candidate gene for BoVl. Expression analysis showed that Bo3g002080 displayed a 2158.85-fold higher expression at albino stage than that in green leaf stage. Transcriptome analysis showed that related pathways of photosynthesis and chloroplast development were significantly enriched in the white sectors, and relevant DEGs involved in these pathways were almost down-regulated. Overall, our study provides a new gene resource for cultivar breeding in ornamental kale and contributes to uncovering the molecular genetic mechanism underlying the variegated leaf formation.

Genetic Analyses for Leaf Variegation in Hybrid Grape Populations (Vitis spp.) Reveals Two Loci, Lvar1 and Lvar2

Variegation in Vitis hybrids was investigated to confirm the inheritance as a single, recessive gene as previously proposed and commonly observed in breeding programs. Variegated leaves have ornamental appeal, but the phenotype is sublethal in some environments. Twenty-nine grape families were characterized for variegation including F1, S1, and S2 populations. The majority segregated 3 wild type (WT):1 variegated and were supported by chi-square tests. Four populations had segregation ratios supporting 15:1 or 1:1 models, and a unique flecking phenotype was identified in a Landot 4511 S1 population that suggested the interaction of two recessive loci. A variegated parent was selfed to produce progeny with no WT offspring and was segregated 0:1. Marker trait associations including bulk segregant analysis (BSA), genome-wide association mapping, and quantitative trait loci (QTL) mapping was used on three populations. On chromosome 14, Lvar1 was identified and mapped to 24.5 to 29.5 Mb and associated closely with rhAmpSeq marker 14_27607541. Lvar2 was associated with rhAmpSeq marker 11_18433819 on chromosome 11 at 12.2 to 18.4 Mb. The identification of two loci and the segregation data in some populations suggest that grape breeding germplasm segregates for two recessive loci. The pedigree records suggest that ‘Frontenac’ inherited one of these loci, and that Landot 4511, an ancestor of many populations tested in this experiment, may carry two loci. A total of 252 candidate genes were identified at these loci, including a key target—adenosine triphosphate (ATP)-dependent zinc metalloprotease FtsH6, involved in photosystem II and similar to the var2 mutant in Arabidopsis. This knowledge can help breeders select for ornamental grapevines or eliminate variegation from their breeding programs.

Cytological, physiological and transcriptomic analysis of variegated Leaves in Primulina pungentisepala offspring

BackgroundPrimulina pungentisepala is suitable for use as a potted plant because of its beautiful leaf variegation, which is significantly different in its selfed offspring. However, the mechanism of P. pungentisepala leaf variegation is unclear. In this study, two types of offspring showing the greatest differences were compared in terms of leaf structure, chlorophyll contents, chlorophyll fluorescence parameters and transcriptomes to provide a reference for studying the molecular mechanism of structural leaf variegation.ResultsAir spaces were found between water storage tissue, and the palisade tissue cells were spherical in the white type. The content of chlorophyll a and total chlorophyll (chlorophyll a + b) was significantly lower in the white type, but there were no significant differences in the content of chlorophyll b, chlorophyll a/b or chlorophyll fluorescence parameters between the white and green types. We performed transcriptomic sequencing to identify differentially expressed genes (DEGs) involved in cell division and differentiation, chlorophyll metabolism and photosynthesis. Among these genes, the expression of the cell division- and differentiation-related leucine-rich repeat receptor-like kinases (LRR-RLKs), xyloglucan endotransglycosylase/hydrolase (XET/H), pectinesterase (PE), expansin (EXP), cellulose synthase-like (CSL), VARIEGATED 3 (VAR3), and ZAT10 genes were downregulated in the white type, which might have promoted the development air spaces and variant palisade cells. Chlorophyll biosynthesis-related hydroxymethylbilane synthase (HEMC) and the H subunit of magnesium chelatase (CHLH) were downregulated, while chlorophyll degradation-related chlorophyllase-2 (CHL2) was upregulated in the white type, which might have led to lower chlorophyll accumulation.ConclusionLeaf variegation in P. pungentisepala was caused by a combination of mechanisms involving structural variegation and low chlorophyll levels. Our research provides significant insights into the molecular mechanisms of structural leaf variegation.

Transcriptome Analysis of Air Space-Type Variegation Formation in Trifolium pratense.

Air space-type variegation is the most diverse among the species of known variegated leaf plants and is caused by conspicuous intercellular spaces between the epidermal and palisade cells and among the palisade cells at non-green areas. Trifolium pratense, a species in Fabaceae with V-shaped air space-type variegation, was selected to explore the application potential of variegated leaf plants and accumulate basic data on the molecular regulatory mechanism and evolutionary history of leaf variegation. We performed comparative transcriptome analysis on young and adult leaflets of variegated and green plants and identified 43 candidate genes related to air space-type variegation formation. Most of the genes were related to cell-wall structure modification (CESA, CSL, EXP, FLA, PG, PGIP, PLL, PME, RGP, SKS, and XTH family genes), followed by photosynthesis (LHCB subfamily, RBCS, GOX, and AGT family genes), redox (2OG and GSH family genes), and nitrogen metabolism (NodGS family genes). Other genes were related to photooxidation, protein interaction, and protease degradation systems. The downregulated expression of light-responsive LHCB subfamily genes and the upregulated expression of the genes involved in cell-wall structure modification were important conditions for air space-type variegation formation in T. pratense. The upregulated expression of the ubiquitin-protein ligase enzyme (E3)-related genes in the protease degradation systems were conducive to air space-type variegation formation. Because these family genes are necessary for plant growth and development, the mechanism of the leaf variegation formation in T. pratense might be a widely existing regulation in air space-type variegation in nature.

VAR2/AtFtsH2 and EVR2/BCM1/CBD1 synergistically regulate the accumulation of PSII reaction centre D1 protein during de-etiolation in Arabidopsis.

Thylakoid FtsH complex participates in PSII repair cycle during high light-induced photoinhibition. The Arabidopsis yellow variegated2 (var2) mutants are defective in the VAR2/AtFtsH2 subunit of thylakoid FtsH complex. Taking advantage of the var2 leaf variegation phenotype, dissections of genetic enhancer loci have yielded novel paradigms in understanding functions of thylakoid FtsH complex. Here, we report the isolation of a new var2 enhancer, enhancer of variegation2-1 (evr2-1). We confirmed that EVR2 encodes a chloroplast protein that was known as BALANCE OF CHLOROPHYLL METABOLISM 1 (BCM1), or CHLOROPHYLL BIOSYNTHETIC DEFECT 1 (CBD1). We showed that EVR2/BCM1/CBD1 was involved in the oligomerization of photosystem I complexes. Genetic assays indicated that general defects in chlorophyll biosynthesis and the accumulation of photosynthetic complexes do not necessarily enhance var2 leaf variegation. In addition, we found that VAR2/AtFtsH2 is required for the accumulation of photosynthetic proteins during de-etiolation. Moreover, we identified PSII core proteins D1 and PsbC as potential EVR2-associated proteins using Co-IP/MS. Furthermore, the accumulation of D1 protein was greatly compromised in the var2-5 evr2-1 double mutant during de-etiolation. Together, our findings reveal a functional link between VAR2/AtFtsH2 and EVR2/BCM1/CBD1 in regulating chloroplast development and the accumulation of PSII reaction centre D1 protein during de-etiolation.

Comparative Analysis of the Metabolome and Transcriptome between the Green and Yellow-Green Regions of Variegated Leaves in a Mutant Variety of the Tree Species Pteroceltis tatarinowii.

In nature, many different factors cause plants to develop variegated leaves. To explore the mechanism of variegated leaf formation in Pteroceltis tatarinowii, a mutant variety (‘Jinyuyuan’), which was induced by ethylmethylsulfone, was selected, and its morphological structure, physiology, biochemistry, transcription and metabolism were analysed. According to differences in colour values, the colours were divided into two regions: a green region and a yellow-green region. The chlorophyll content of the two regions was significantly different. Moreover, the yellow-green regions of the leaves were significantly thinner than the green regions. The chloroplast ultrastructure in the yellow-green region revealed small chloroplasts, large vacuoles, small starch grains, obviously increased numbers of osmophilic grains, loose lamellae of the inner capsule and thin lamellae. Moreover, the yellow-green region was accompanied by oxidative stress, and the activity of the oxidative phosphorylation pathway related to oxidative activity in the transcriptome showed an upward trend. Vitamin B6 and proline contents also increased, indicating that the antioxidant activity of cells in the yellow-green region increased. Transcriptomic and metabolomic analysis showed that the differentially expressed genes (DEGs) related to chlorophyll synthesis and metabolism led to a decrease in the photosynthesis and then a decrease in the assimilation ability and contents of sucrose, starch and other assimilates. Amino acid synthesis and metabolism, lipid synthesis and the activity of metabolic pathways were obviously downregulated, and the contents of differentially accumulated metabolites associated with amino acids and lipids were also reduced. At the same time, 31 out of 32 DEGs involved in the flavonoid synthesis pathway were downregulated, which affected leaf colour. We hypothesized that the variegated leaves of P. tatarinowii ‘Jinyuyuan’ are caused by transcriptional and post-transcriptional regulation. Mutations in pigment and flavonoid synthesis pathway genes and transcription factor genes directly affect both pigment and flavonoid synthesis and degradation rate, which in turn affect carbon assimilation, carbon fixation, related protein synthesis and enzyme activity, lipid synthesis and degradation and the activity of other metabolic pathways, eventually leading to the formation of different colour regions.

Morphological diversity and phenetic relationship of wild and cultivated Begonia based on morphology and leaf venation

Abstract. Permata DA, Susandarini R. 2021. Morphological diversity and phenetic relationship of wild and cultivated Begonia based on morphology and leaf venation. Biodiversitas 23: 928-937. Begonia is an ornamental plant with intense cultivation and hybridization practices because of the uniqueness and beauty of its leaves. Begonia with a very large number of species is interesting to study, especially because Indonesia is one of the resource centers of this genus diversity as indicated by the increasing number of new species found every year. This study aimed to explore the morphological diversity of wild and cultivated Begonia and reveal the phenetic relationships of the species and hybrids based on morphology and leaf venation patterns. In this study, we used 19 Begonia samples belonging to five species collected from their natural habitat and 14 species and hybrids obtained from the nurseries. Morphological observations of living specimens and examination on microscopic slides of cleared leaf resulted in 28 characters which were used to determine phenetic relationships using cluster analysis. The high variability of leaf venation patterns described in this study disclosed the micromorphological diversity of Begonia which has not been widely exposed. The results of morphological observations showed high variabilities in leaf color, leaf shape, and petiole color. The results of cluster analysis and principal component analysis indicated that the grouping of species was mainly determined by the existence of trichomes on leaf surfaces and petiole, leaf venation pattern, leaf variegation, and leaf shape. The grouping of species resulting from cluster analysis can be used in the selection of potential parents to produce new Begonia hybrids through crossing experiments.

Role of Rubisco Activase from Cymbidium with Variegated Leaves in Dendrobium Officinale

Role of Rubisco Activase from Cymbidium with Variegated Leaves in Dendrobium Officinale

Genes for Yield Stability in Tomatoes

Breeding plant varieties with adaptation to unstable environments requires some knowledge about the genetic control of yield stability. To further this goal, a meta-analysis of 12 years of field harvest data of 76 Solanum pennellii introgression lines (ILs) is conducted. Five quantitative trait loci (QTL) affecting yield stability are mapped; IL10-2-2 is unique as this introgression improved yield stability without affecting mean yield both in the historic data and in four years of field validations. Another dimension of the stability question is which genes when perturbed affect yield stability. For this the authors tested in the field 48 morphological mutants and found one 'canalization' mutant (canal-1) with a consistent effect of reducing the stability of a bouquet of traits including leaf variegation, plant size and yield. canal-1 mapped to a DNAJ chaperone gene (Solyc01g108200) whose homologues in C. elegans regulate phenotypic canalization. Additional alleles of canal-1 are generated using CRISPR/CAS9 and the resulting seedlings have uniform variegation suggesting that only specific changes in canal-1 can lead to unstable variegation and yield instability. The identification of IL10-2-2 demonstrates the value of historical phenotypic data for discovering genes for stability. It is also shown that a green-fruited wild species is a source of QTL to improve tomato yield stability.

Characterization of Anatomical and Physiological Effects of Variegation Mutation on Grapevine

Variegation is a common trait in plants that characteristically displays white or off-colored plant tissue. In grapevine, leaf variegation is expressed as white and pale green leaf tissue resulting in plants that are stunted in growth and hindered in development. In this study, several experiments were performed to investigate the impact of this mutation has on the anatomy of grape leaves and physiology of the plant. Histological staining of variegated and nonvariegated leaf tissue transections showed alterations to the leaf palisade mesophyll structure that affected leaf tissue width. An assay quantifying leaf pigments was performed to compare chlorophyll and carotenoid concentrations in leaves between variegated and wild-type seedlings, which showed that variegated leaf samples had reduced chlorophyll and carotenoid concentration. Through fluorescence imaging, we determined that photochemical efficiency of photosystem II (PSII) is reduced in variegated seedlings. By growing variegated and wild-type plants under high, medium, and low light intensities that variegated plants exposed to higher light intensity reduces the phenotypic expression of the variegation trait. Also, we found variegated plants to have significant reductions in growth traits such as plant height, leaf number, branch number, and dry weight compared with wild-type phenotype plants. Overall, our experiments revealed the variegation mutation altered normal leaf development causing significant effects to grapevine physiology.

Characterization and potential utilization of recently available milk thistle, Silybum marianum (L.) Gaertn., wild type and mutant accessions

AbstractMilk thistle, Silybum marianum (L.) Gaertn. (Asteraceae), is an economically important medicinal plant utilized for silymarin production. Moreover, the species has been positively evaluated for vegetable oil and biomass production. Despite these positive characteristics, milk thistle is still marked by traits that are typical of undomesticated species (most importantly natural fruit dispersal at maturity) and requires further genetic improvement for its complete exploitation. This manuscript summarizes all the information collected through time about a collection of nine milk thistle wild and mutant lines and it discusses the possible further utilization of these genotypes. The accessions are characterized by interesting traits related to: fruit silymarin composition (S. marianum chemotype A and B), fruit fatty acid composition (high oleic and high stearic acid lines), fruit condensed tannins content, vegetative biomass composition (modification of xylans or lignin content), vegetative biomass structure (dwarf and tall lines), modifications of leaf variegation (hypervareigated line) and different types of fruit shatter resistance at maturity. All the lines underwent subsequent generations of selfing and are stable for all the described traits. The accessions will be made available at the Genebank of the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK, Gatersleben) and may prove to be a useful genetic material for the improvement of qualitative fruit traits (silymarin quality, fatty acid composition) and for the further development of shatter-resistant S. marianum genotypes towards the complete domestication of this promising species.

Disruption of Photomorphogenesis Leads to Abnormal Chloroplast Development and Leaf Variegation in Camellia sinensis.

Camellia sinensis cv. ‘Yanlingyinbiancha’ is a leaf-variegated mutant with stable genetic traits. The current study aimed to reveal the differences between its albino and green tissues, and the molecular mechanism underlying the variegation. Anatomic analysis showed the chloroplasts of albino tissues to have no intact lamellar structure. Photosynthetic pigment in albino tissues was significantly lower than that in green tissues, whereas all catechin components were more abundant in the former. Transcriptome analysis revealed most differentially expressed genes involved in the biosynthesis of photosynthetic pigment, photosynthesis, and energy metabolism to be downregulated in albino tissues while most of those participating in flavonoid metabolism were upregulated. In addition, it was found cryptochrome 1 (CRY1) and phytochrome B (PHYB) genes that encode blue and red light photoreceptors to be downregulated. These photoreceptors mediate chloroplast protein gene expression, chloroplast protein import and photosynthetic pigment biosynthesis. Simultaneously, SUS gene, which was upregulated in albino tissues, encodes sucrose synthase considered a biochemical marker for sink strength. Collectively, we arrived to the following conclusions: (1) repression of the biosynthesis of photosynthetic pigment causes albinism; (2) destruction of photoreceptors in albino tissues suppresses photomorphogenesis, leading to abnormal chloroplast development; (3) albino tissues receive sucrose from the green tissues and decompose their own storage substances to obtain the energy needed for survival; and (4) UV-B signal and brassinosteroids promote flavonoid biosynthesis.

Nuaulu Use and Management of Culturally Salient Polymorphisms inCodiaeum variegatum: Explaining the Biocultural Dimensions of Leaf Variegation in a Southeast Asian Ornamental

Codiaeum variegatum has become a well-known ornamental plant in Europe and North America and has long been culturally significant in Southeast Asia and the Pacific, for example as a boundary plant. This paper asks, firstly, how variations in foliage are classified, managed, and valued in one population (Nuaulu on the island of Seram, eastern Indonesia), and how this relates to the range of uses to which these variations are put. Secondly, the paper suggests that this particular case helps shed light on the importance of leaf variegation as an organoleptic quality in the context of biocultural evolution. It is noted that the features that evolved in its area of endemism are those making it attractive as an ornamental globally. While color variations in foliage combining genotypic cultivar differences, clonal differences, and age-dependent differences produce phenotypic instability and are a problem for ornamental plant producers in a commercial context, they are not a problem for Nuaulu.

Cytological and Transcriptomic Analysis Provide Insights into the Formation of Variegated Leaves in Ilex × altaclerensis 'Belgica Aurea'.

Ilex × altaclerensis ‘Belgica Aurea’ is an attractive ornamental plant bearing yellow-green variegated leaves. However, the mechanisms underlying the formation of leaf variegation in this species are still unclear. Here, the juvenile yellow leaves and mature variegated leaves of I. altaclerensis ‘Belgica Aurea’ were compared in terms of leaf structure, pigment content and transcriptomics. The results showed that no obvious differences in histology were noticed between yellow and variegated leaves, however, ruptured thylakoid membranes and altered ultrastructure of chloroplasts were found in yellow leaves (yellow) and yellow sectors of the variegated leaves (variegation). Moreover, the yellow leaves and the yellow sectors of variegated leaves had significantly lower chlorophyll compared to green sectors of the variegated leaves (green). In addition, transcriptomic sequencing identified 1675 differentially expressed genes (DEGs) among the three pairwise comparisons (yellow vs. green, variegation vs. green, yellow vs. variegation). Expression of magnesium-protoporphyrin IX monomethyl ester (MgPME) [oxidative] cyclase, monogalactosyldiacylglycerol (MGDG) synthase and digalactosyldiacylglycerol (DGDG) synthase were decreased in the yellow leaves. Altogether, chlorophyll deficiency might be the main factors driving the formation of leaf variegation in I. altaclerensis ‘Belgica Aurea’.

A case study of using an efficient CRISPR/Cas9 system to develop variegated lettuce

The clustered, regularly interspaced, short palindromic repeat associated endonuclease 9 (CRISPR/Cas9) system has emerged as a powerful approach for precision breeding to create plants with desirable traits. However, the CRISPR/Cas9 system relies heavily on an efficient plant transformation system that is usually time-consuming and costly. Here, we have constructed a CRISPR-Cas9 vector with neomycin phosphotransferase II and green fluorescent protein (eGFP-NPTII), where the high expression of GFP during plant regeneration allowed us to minimize the positional effect on T-DNA expression and facilitate screening T-DNA-free mutants. Successful gene editing using CRISPR/Cas9 has been illustrated in different plant species, but an important aesthetic characteristic of leaf variegation remained unexplored. With the newly designed construct, we have targeted the variegation gene <i>LsVAR2</i> in lettuce. Our results indicated that <i>LsVAR2</i> is closely related to both <i>AtFtsH2</i> and <i>AtFtsH8</i>, in which homozygous mutations lead to an albino phenotype while a variegated phenotype was induced by CRISPR/Cas9 <i>de novo</i> gene editing. In conclusion, the unique design of our CRISPR/Cas9 construct could efficiently edit the target gene and ease the screening of non-TDNA mutants through detecting GFP signals during plant regeneration and progeny segregation. Additionally, the success of gene-editing of <i>LsVAR2</i> in lettuce demonstrates proof in this method to develop novel plant breeding materials for valuable horticultural plant species.

Exploring ELT practices, teachers’ professional profile and beliefs: Analysing data from the PRIN survey and envisaging pedagogical projections

This paper presents selected findings emerging from the survey related to the PRIN Prot. 2015REZ4EZ questionnaire, created and administered by the Unit 3 of the same PRIN project. This tool of investigation was specially devised in order to research and acquire the main values and beliefs ascribable to a volunteer group of teachers, operating in the Italian territory and catering for different levels of education in the national system. From the authentic data collected, it is possible to draw an overall profile of those professionals engaged in the diversified educational contexts above referred to. Even though still connected to and partially influenced by a SE and native-speaker’s model authority, there is evidence of the presence of an active ELF-aware perspective emerging from the respondents; the qualifying questions where this aspect specifically occurs are analyzed in details, particularly in relation to which sociolinguistic model of English are those teachers inspired by in their teaching. Furthermore, those values and beliefs, in connection to the pedagogical approach of choice, are interpreted from a prospective point of view, envisioning their potential developments in the future, also projecting them into the frame of reference provided by a social constructivist model as designed by Kurt Kohn in MY English (2018) and further developments (forthcoming 2020). The emancipation of the ELF users and their adaptive appropriation of the lingual capabilities inherent in the ELF-aware approach, together with the acknowledgement of the ELF-users’ expressive means affordable according to that perspective, are highilighted, also in terms of individual and collective creativity, from the side of both teachers and learners, in the variegated educational contexts.

A revised classification of leaf variegation types

Variegated leaf plants are a group of plants with stable patterns of differently colored leaf areas. The variously colored patches on the surface of the leaves have important biological functions in plant reproduction and adaptation to the environment. Apart from that, these plants have attracted interest as valuable ornamental plants. In this study, 1710 species with variegated leaves belonging to 78 families were investigated based on field-collected samples and previous literature, including transverse sections of 117 species. The macroscopic patterns of variegated leaves are highly diverse and can be distinguished as fishbone-shaped, blotched, V-shaped, spotted, striped, reticulate, and pinnate, with varying levels of diversity across different families and genera. We classified variegated leaves into five types according to the location, shape, color, and cross-sectional structure of the differently colored leaf areas. These are: I, chlorophyll type; II, air space type; III, epidermis type; IV, pigment type; and V, appendages type. Type II is the most common type, which is found in approximately 56% of all variegated leaf species, whereas type V is newly defined to accommodate the variegated leaves with colored, unequally distributed, multicellular outgrowths on the epidermis. Relationships between the diverse macroscopic patterns and the five structural types are discussed.

SPLICING FACTOR1 Is Important in Chloroplast Development under Cold Stress.

RNA SPLICING FACTOR1 (SF1) is responsible for recognizing the branch point site (BPS) sequence in introns and is critical for pre-mRNA splicing. In Arabidopsis (Arabidopsis thaliana), splicing factor1 (AtSF1) has been shown to retain the conserved function, but it is unexpected that null atsf1 mutants are viable. Here, we identified an allele of atsf1, named suppressor of thf1-4 (sot4), from suppressor screening for leaf variegation of thylakoid formation1 The sot4 mutant resulting from the G-to-R mutation at the highly conserved 198th amino acid residue within the functionally unknown domain exhibits leaf virescence associated with less accumulation of mature plastid ribosomal RNA, particularly under cold stress. Interestingly, the same point mutation in yeast Saccharomyces cerevisiae MUD synthetic-lethal 5p (SF1/Msl5p) also causes hypersensitivity to coldness and a low splicing activity for the introns with suboptimal BPS sequences. Transcriptomic profiling and reverse-transcription quantitative PCR analyses showed that expression of many genes were up- or downregulated in atsf1 via insufficient intron splicing. Our search for a BPS consensus from the retained introns in atsf1 transcriptomes, combined with RNA electrophoresis mobility shift assays, revealed that AtSF1 directly binds to the BPS consensus containing 5'-CU(U/A)AU-3'. Taken together, our data provide insight into a role for AtSF1 in regulating intron splicing efficiency, which helps plants acclimate to coldness.

Involvement of CsERF2 in leaf variegation of Cymbidium sinense \u2018Dharma\u2019

Main conclusionCsERF2, an ethylene response factor, plays a role in leaf variegation.Leaf variegation is a main ornamental characteristic in Cymbidium sinense (C. sinense). However, the mechanisms of leaf color variegation remain largely unclear. In the present study, we analyzed the cytological and physiological features, as well as molecular analyses of leaves from wild-type (WT) and leaf variegation mutants of Cymbidium sinense ‘Dharma’. Chloroplasts with typical and functional structures were discovered in WT and green sectors of the mutants leaves (MG), but not in yellow sectors of the mutant leaves (MY). The activities of key enzymes involved in chlorophyll (Chl) degradation and their substrate contents were significantly increased in MY. Genes related to Chl degradation also showed a significant up-regulation in MY. Transcriptomic analysis showed that the expression of all identified ethylene response factors (ERFs) was significantly up-regulated, and the 1-aminocyclopropane-1-carboxylic acid (ACC) content in MY was significantly higher compared with MG. QRT-PCR analysis validated that the expression levels of genes related to Chl degradation could be positively affected by ethylene (ETH) treatment. Stable overexpression of CsERF2 in Nicotiana tabacum (N. tabacum) led to a decrease in Chl content and abnormal chloroplast. Transcriptomic analysis and qRT-PCR results showed that the KEGG pathway related to chloroplast development and function showed significant change in transgenic N. tabacum. Therefore, the leaf color formation of C. sinense was greatly affected by chloroplast development and Chl metabolism. CsERF2 played an important role in leaf variegation of C. sinense.

Differential growth response of green and variegated Ficus benjamina to exogenous cytokinin and shade

Abstract Benjamin fig (Ficus benjamina) is an important foliage and landscape crop species comprising green and variegated genotypes. The latter develop leaves with yellow and white leaf areas which may impose lower photosynthetic activity, thus resulting in slower growth than green genotypes. In many species, the exogenous supply of cytokinin to pot-grown plants promotes growth, mainly due to enhanced carbon fixation. In this work, we analyze the effect of spraying the cytokinin 6-benzylaminopurine (BAP) on growth and development of green and variegated Ficus benjamina genotypes. Two experiments were carried out in a greenhouse, in which either different number of BAP applications (Experiment 1) or different BAP concentrations (Experiment 2) were tested. In Experiment 2, plants were grown under three different light intensities. BAP sprays promoted rate of leaf appearance, leaf expansion and whole-plant growth, and the effect was stronger in variegated than in green plants. The relative growth rate promotion by BAP was associated with increased net assimilation rate rather than with variation in the leaf area ratio. On the other hand, shading had a more negative impact on growth and development of variegated plants than in green ones. Variegated plants, unlike green ones, developed leaves with high specific leaf area under the lowest light intensity. This led to high leaf area ratio values, which helped to maintain relative growth rates close to those of plants under moderate shading.