Thermal degradation of red cabbage (Brassica oleracea L. var. Capitata f. rubra) anthocyanins in a water model extract under accelerated shelf-life testing.

Red cabbage (RC) represents a source of anthocyanins acylated with hydroxycinnamic acids (HCA) that are described to enhance their stability. Nevertheless, data about their thermal degradation are still controversial. Our aim was to comprehensively analyse the degradation kinetics of individual RC anthocyanins in a model aqueous extract treated at 40 °C × 30 days to simulate severe but realistic storage conditions. Free anthocyanins and radical-scavenging capacity showed different kinetics. The results confirm the high stability of RC anthocyanins (t1/2: 16.4-18.4 days), although HPLC analyses of each molecule displayed distinct kinetics with t1/2 from 12.6 to 35.1 days. In particular, the sinapoyl acylation negatively affected the stability of the anthocyanins, while the forms monoacylated with glycosyl p-coumaric and ferulic acids exhibited higher stability. In conclusion, our results indicate that acylation is not a prerogative of stability, as this is instead more dependent on specific acylation patterns and the glycosylation of HCA.

Applying productivity and phytonutrient profile criteria in modelling species selection of microgreens as Space crops for astronaut consumption.

Introduction: Long-duration missions in outer Space will require technologies to regenerate environmental resources such as air and water and to produce food while recycling consumables and waste. Plants are considered the most promising biological regenerators to accomplish these functions, due to their complementary relationship with humans. Plant cultivation for Space starts with small plant growth units to produce fresh food to supplement stowed food for astronauts' onboard spacecrafts and orbital platforms. The choice of crops must be based on limiting factors such as time, energy, and volume. Consequently, small, fast-growing crops are needed to grow in microgravity and to provide astronauts with fresh food rich in functional compounds. Microgreens are functional food crops recently valued for their color and flavor enhancing properties, their rich phytonutrient content and short production cycle. Candidate species of microgreens to be harvested and eaten fresh by crew members, belong to the families Brassicaceae, Asteraceae, Chenopodiaceae, Lamiaceae, Apiaceae, Amarillydaceae, Amaranthaceae, and Cucurbitaceae. Methods: In this study we developed and applied an algorithm to objectively compare numerous genotypes of microgreens intending to select those with the best productivity and phytonutrient profile for cultivation in Space. The selection process consisted of two subsequent phases. The first selection was based on literature data including 39 genotypes and 25 parameters related to growth, phytonutrients (e.g., tocopherol, phylloquinone, ascorbic acid, polyphenols, lutein, carotenoids, violaxanthin), and mineral elements. Parameters were implemented in a mathematical model with prioritization criteria to generate a ranking list of microgreens. The second phase was based on germination and cultivation tests specifically designed for this study and performed on the six top species resulting from the first ranking list. For the second selection, experimental data on phytonutrients were expressed as metabolite production per day per square meter. Results and discussion: In the final ranking list radish and savoy cabbage resulted with the highest scores based on their productivity and phytonutrient profile. Overall, the algorithm with prioritization criteria allowed us to objectively compare candidate species and obtain a ranking list based on the combination of numerous parameters measured in the different species. This method can be also adapted to new species, parameters, or re-prioritizing the parameters for specific selection purposes.

Defining growth requirements of microgreens in space cultivation via biomass production, morpho-anatomical and nutritional traits analysis.

During long-term manned missions to the Moon or Mars, the integration of astronauts' diet with fresh food rich in functional compounds, like microgreens, could strengthen their physiological defenses against the oxidative stress induced by the exposure to space factors. Therefore, the development of targeted cultivation practices for microgreens in space is mandatory, since the cultivation in small, closed facilities may alter plant anatomy, physiology, and resource utilization with species-specific responses. Here, the combined effect of two vapor pressure deficit levels (VPD: 0.14 and 1.71 kPa) and two light intensities (150 and 300 µmol photons m-2 s-1 PPFD) on two species for microgreen production (Brassica oleracea var. capitata f. sabauda 'Vertus' and Raphanus raphanistrum subsp. sativus 'Saxa'), was tested on biomass production per square meter, morpho-anatomical development, nutritional and nutraceutical properties. Microgreens were grown in fully controlled conditions under air temperature of 18/24°C, on coconut fiber mats, RGB light spectrum and 12 h photoperiod, till they reached the stage of first true leaves. At this stage microgreens were samples, for growth and morpho-anatomical analyses, and to investigate the biochemical composition in terms of ascorbic acid, phenols, anthocyanin, carotenoids, carbohydrates, as well as of anti-nutritional compounds, such as nitrate, sulfate, and phosphate. Major differences in growth were mostly driven by the species with 'Saxa' always presenting the highest fresh and dry weight as well as the highest elongation; however light intensity and VPDs influenced the anatomical development of microgreens, and the accumulation of ascorbic acid, carbohydrates, nitrate, and phosphate. Both 'Saxa' and 'Vertus' at low VPD (LV) and 150 PPFD increased the tissue thickness and synthetized high ß-carotene and photosynthetic pigments. Moreover, 'Vertus' LV 150, produced the highest content of ascorbate, fundamental for nutritional properties in space environment. The differences among the treatments and their interaction suggested a relevant difference in resource use efficiency. In the light of the above, microgreens can be considered suitable for cultivation in limited-volume growth modules directly onboard, provided that all the environmental factors are combined and modulated according to the species requirements to enhance their growth and biomass production, and to achieve specific nutritional traits.

Preparation of novel authentication film by screen printing of anthocyanin biomolecular extract: Thermochromism and vapochromism.

Novel thermochromic and vapochromic paper substrates were prepared via screen printing with anthocyanin extract in the presence of ferrous sulfate mordant, resulting in multi-stimuli responsive colorimetric paper sheets. Environmentally friendly anthocyanin extract was obtained from red-cabbage (Brassica oleracea var. capitata L.) to function as spectroscopic probe in coordination with ferrous sulfate mordant. Pink anthocyanin/resin nanocomposite films immobilized onto paper surface were developed by well-dispersion of anthocyanin extract as a colorimetric probe in a binding agent without agglomeration. As demonstrated by CIE colorimetric studies, the pink (λmax = 418 nm) film deposited onto paper surface turns greenish-yellow (λmax = 552 nm) upon heating from 25 to 75°C, demonstrating new thermochromic film for anti-counterfeiting applications. The thermochromic effects were investigated at different concentrations of the anthocyanin extract. Upon exposure to ammonia gas, the color of the anthocyanin-printed sheets changes rapidly from pink to greenish-yellow, and then immediately returns to pink after taking the gaseous ammonia stimulus away, demonstrating vapochromic effect. The current sensor strip showed a detection limit for ammonia gas in the range 50-300 ppm. Both thermochromism and vapochromism showed high reversibility without fatigue. In addition to studying the rheological properties of the prepared composites, the morphological and mechanical properties of the printed cellulose substrates were also studied.

Innovative air-impingement jet drying of red cabbage: Kinetic description and prediction of the degradation of cyanidin-3-diglucoside-5-glucoside and cyanidin.

Red cabbage (RC) is a vegetable rich in anthocyanins. This study analyzed comparative applications of RC hot air drying (HAD) at 60 °C, which took 810 min, and RC air-impingement jet drying (AIJD) at 60 °C, which took 630 min. The results indicated that AIJD retained a better color in the RC than HAD. Ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS) analysis of the RC showed that 28 anthocyanins and one anthocyanidin (cyanidin (C)) were derived from cyanidin-3-diglucoside-5-glucoside (C3dG5G). Multivariate analysis revealed that AIJD degraded the C3dG5G and C in the RC, which were revealed as 1.5-order and 2-order reactions, respectively. Moreover, the AIJD-induced degradation of C3dG5G and C were non-spontaneous and endothermic reactions. These kinetic equations could also be applied to predict the content of C3dG5G and C during degradation. Therefore, the results of this study could be beneficial in improving the AIJD of RC for more effective preservation.

A triple test cross analysis to detect epistatic gene effects in cabbage (Brassica oleracea var. capitata L.): An updated methodology.

The cross-pollinated crop Brassica oleracea var. capitata L. shows good heterotic heterosis at high output; better standing of the plants; early maturity; larger and more homogeneous heads; consistency of head compactness; and disease-tolerance in F1 hybrids. There is very limited information documented on the epistasis of essential cabbage characters. We expand the research in this study to include an upgraded test to cross-design for enrolling and estimating epistasis and other genetic variance components controlling head yield and component traits in cabbage. The data was obtained from 45 families produced by crossing 15 lines with three testers; SC 2008-09, E-1-3-1&2, and their single cross F1, was subjected to triple test cross analysis. The current study results confirmed "j + 1" form of epistasis which is a major component for all traits. The plant spread, non-wrapper leaves, nethead/grossweight, polar/equatorial diameter, marketable head yield per plot, iron content and dry matter lugged both "j + 1" and 'i' type with the predominance of the 'i' type of interaction. Except for head shape index, equatorial diameter, head compactness was more noticeable when observed in dominance component. The degree of dominance is in the partial range, but both the head shape index/compactness and equatorial diameter showed over dominance. For maximum part, superiority was shown in both the directions. Appropriate breeding procedures are proposed to exploit the different forms of gene effects discovered for genetic improvement of head yield and quality traits.

Green biosynthesis, characterization, and cytotoxic effect of magnetic iron nanoparticles using Brassica Oleracea var capitata sub var rubra (red cabbage) aqueous peel extract.

The green method of nanoparticle synthesis, which is an environment and living-friendly method, is an updated subject that has appeared as an alternative to conventional methods such as physical and chemical synthesis. In this presented study, the green synthesis of magnetic iron oxide nanoparticles (IONPs) from iron (III) chloride by using Brassica oleracea var. capitata sub.var. rubra aqueous peel extract has been reported. The prepared IONPs were characterized with fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-VIS), zeta potential, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The cytotoxic effects of IONPs on MCF-7 breast cancer cell line were studied by MTT assay, and migrative effect of its were carried out by the wound healing assay. It was found that the mean particle size of IONPs was 675 ± 25 nm, and the polydispersity index was 0.265 PDI. It was also determined that these nanoparticles had an anti-proliferative impact on the MCF-7 breast cancer cell line depending on the dosage. Characterization results support the successful synthesis of nanoparticles, and the dose-dependent cytotoxic effects of nanoparticles on MCF-7 cells also make it a potential chemotherapeutic agent for breast cancer treatment.

Pseudomonas lactucae sp. nov., a pathogen causing bacterial rot of lettuce in Japan.

Two phytopathogenic bacteria, MAFF 301380T and MAFF 301381, isolated from rot lesions of lettuce (Lactuca sativa L. var. capitata L.) in Japan, were characterized using a polyphasic approach. The cells were Gram-reaction-negative, aerobic, non-spore-forming, rod-shaped and motile with one to three polar flagella. Analysis of the 16S rRNA gene sequences showed that the strains belong to the genus Pseudomonas and are closely related to Pseudomonas cedrina subsp. cedrina CFML 96-198T (99.72 %), Pseudomonas cedrina subsp. fulgida P515/12T (99.65 %), Pseudomonas gessardii DSM 17152T (99.51 %), Pseudomonas synxantha DSM 18928T (99.44 %), Pseudomonas libanensis CIP 105460T (99.44 %) and Pseudomonas lactis DSM 29167T (99.44 %). The genomic DNA G+C content was 60.4 mol% and the major fatty acids consisted of summed feature 3 (C16 : 1 ω7c/C16 : 1 ω6c), C16 : 0 and summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c). Phylogenetic analysis using the rpoD gene sequences and phylogenomic analyses based on the whole genome sequences demonstrated that the strains are members of the Pseudomonas fluorescens subgroup but formed a monophyletic and robust clade separated from their closest relatives. The average nucleotide identity and digital DNA-DNA hybridization values between the strains and their closely related species were 88.65 % or less and 36.3 % or less, respectively. The strains could be distinguished from their closest relatives by phenotypic characteristics, pathogenicity towards lettuce and whole-cell MALDI-TOF MS profiles. The evidence presented in this study supports the classification of the strains as representing a novel Pseudomonas species, for which we propose the name Pseudomonas lactucae sp. nov., with the type strain MAFF 301380T (=ICMP 23838T).

Comparative Transcriptomic Analysis of Gene Expression Inheritance Patterns Associated with Cabbage Head Heterosis.

The molecular mechanism of heterosis or hybrid vigor, where F1 hybrids of genetically diverse parents show superior traits compared to their parents, is not well understood. Here, we studied the molecular regulation of heterosis in four F1 cabbage hybrids that showed heterosis for several horticultural traits, including head size and weight. To examine the molecular mechanisms, we performed a global transcriptome profiling in the hybrids and their parents by RNA sequencing. The proportion of genetic variations detected as single nucleotide polymorphisms and small insertion-deletions as well as the numbers of differentially expressed genes indicated a larger role of the female parent than the male parent in the genetic divergence of the hybrids. More than 86% of hybrid gene expressions were non-additive. More than 81% of the genes showing divergent expressions showed dominant inheritance, and more than 56% of these exhibited maternal expression dominance. Gene expression regulation by cis-regulatory mechanisms appears to mediate most of the gene expression divergence in the hybrids; however, trans-regulatory factors appear to have a higher effect compared to cis-regulatory factors on parental expression divergence. These observations bring new insights into the molecular mechanisms of heterosis during the cabbage head development.

Brassica oleracea var. capitata f. alba: A Review on its Botany, Traditional uses, Phytochemistry and Pharmacological Activities.

BACKGROUND: Brassica oleracea var. capitata f. alba (white cabbage) is a cruciferous vegetable used as a vegetable and traditional medicine all over the world. Different preparation from several parts of the plant- roots, shoots, leaves, and the whole plant are used to treat a wide range of diseases, including diabetes, cancer, gastric, inflammation, hypertension, hypercholesterolemia, bacterial, oxidation, and obesity. OBJECTIVE: The aim of the current review is to evaluate the botany, distribution, traditional uses, phytochemistry, and pharmacological activities of B. oleracea var. capitata. Moreover, this review will guide to fill the existing gaps in information and highlight additional research prospects in the field of phytochemistry and pharmacology. METHOD: Various resources, including research papers, review papers, books, and reports, were collected to obtain overall information on Brassica oleracea var. capitata, which were obtained by an online search of worldwide-accepted scientific databases. Phytochemical constituents' structures were drawn by ChemDraw software. RESULTS: About 72 isolated phytochemical compounds of B. oleracea var. capitata have been collected from different articles, which included different types of compounds such as alkaloids, flavonoids, organic acids, glucosinolates, steroids, hydrocarbons, etc. Crude extracts and phytoconstituents of B. oleracea var. capitata have various pharmacological effects, including antidiabetic, anticancer, antihypertensive, anticholesterolemic, antioxidant, anti-inflammatory, antibacterial, anti-obesity, anticoagulant, and hepatoprotective. We have enlisted all these pharmacological data along with all the phytochemical constituents of Brassica oleracea var. capitata. CONCLUSION: The study was focused on the traditional uses, pharmacological activities, and phytochemistry of Brassica oleracea var. capitata, and the findings indicated that B. oleracea var. capitata is an important medicinal plant that shows several pharmacological effects. We hope our review of this plant will provide more basic and useful information and fill some research gaps for further investigation and drug design. Although we found some important traditional uses and pharmacological activities of Brassica oleracea var. capitata, there is insufficient work in the field of phytochemical activities.

Application of a Combined Transmittance/Fluorescence Leaf Clip Sensor for the Nondestructive Determination of Nitrogen Status in White Cabbage Plants.

The correct fertilization of vegetable crops is commonly determined on the basis of soil and plant costly destructive analyses, demanding more sustainable non-invasive optical detection. Here, we tested the ability of the combined transmittance/fluorescence leaf clip Dualex device for determining the nitrogen (N) status of cabbage plants. Fully developed leaves from plants grown under different N rates of 0; 100; 200; 300 kg N ha-1 in 2018 and 2019 were measured in the field by the Dualex sensor twice a year in July and October. The chlorophyll (Chl) and nitrogen (nitrogen balance index, NBI) indices and the flavonols (Flav) index of the sensor were positively and negatively correlated to leaf nitrogen, respectively. Merging the two-years data, the NBI versus leaf N correlation was less point dispersed in October than July (R2 = 0.76 and 0.64, respectively). NBI was also correlated to cabbage yield, better in July than October. Our results showed that the multiparametric Dualex device can be used as precision agriculture tool for the early prediction of plant N and cabbage yield with economic advantage for the growers and reduced environmental contamination due to nitrate leaching.

Genome Sequence of Fusarium oxysporum f. sp. conglutinans, the Etiological Agent of Cabbage Fusarium Wilt.

Fusarium oxysporum f. sp. conglutinans is the causal agent of Fusarium wilt of cabbage (Brassica oleracea var. capitata L.), which results in severe yield loss. Here, we report a high-quality genome sequence of a race 1 strain (IVC-1) of F. oxysporum f. sp. conglutinans, which was assembled using a combination of PacBio long-read and Illumina short-read sequences. The assembled IVC-1 genome has a total size of 71.18 Mb, with a contig N50 length of 4.59 Mb, and encodes 23,374 predicted protein-coding genes. The high-quality genome of IVC-1 provides a valuable resource for facilitating our understanding of F. oxysporum f. sp. conglutinans-cabbage interaction.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Crop Management in Controlled Environment Agriculture (CEA) Systems Using Predictive Mathematical Models.

Proximal sensors in controlled environment agriculture (CEA) are used to monitor plant growth, yield, and water consumption with non-destructive technologies. Rapid and continuous monitoring of environmental and crop parameters may be used to develop mathematical models to predict crop response to microclimatic changes. Here, we applied the energy cascade model (MEC) on green- and red-leaf butterhead lettuce (Lactuca sativa L. var. capitata). We tooled up the model to describe the changing leaf functional efficiency during the growing period. We validated the model on an independent dataset with two different vapor pressure deficit (VPD) levels, corresponding to nominal (low VPD) and off-nominal (high VPD) conditions. Under low VPD, the modified model accurately predicted the transpiration rate (RMSE = 0.10 Lm-2), edible biomass (RMSE = 6.87 g m-2), net-photosynthesis (rBIAS = 34%), and stomatal conductance (rBIAS = 39%). Under high VPD, the model overestimated photosynthesis and stomatal conductance (rBIAS = 76-68%). This inconsistency is likely due to the empirical nature of the original model, which was designed for nominal conditions. Here, applications of the modified model are discussed, and possible improvements are suggested based on plant morpho-physiological changes occurring in sub-optimal scenarios.

Variation in Macronutrient Content, Phytochemical Constitution and In Vitro Antioxidant Capacity of Green and Red Butterhead Lettuce Dictated by Different Developmental Stages of Harvest Maturity.

Rising life expectancy and the demanding modern lifestyle drive the growing appeal of healthy and balanced diets centered on vegetable and fruit consumption. Functional, phytonutrient-packed and principally raw food is in high demand. Microgreens constitute such a novel functional food that combines a high sensory and bioactive value, which invites comparison to their mature-leaf counterparts. For this purpose, a controlled environment chamber experiment was carried out to compare the mineral, phytochemical and antioxidant capacity attributes of two-pigmented Lactuca sativa L. var. capitata cultivars (green and red Salanova®) harvested at the microgreens and the mature-leaf stage. Macronutrients were assessed through ion chromatography, while carotenoids and polyphenols were assessed and quantified through HPLC-DAD and UHPLC-Q-Orbitrap HRMS, respectively. Calcium and magnesium were higher in microgreens irrespective of the cultivar; conversely, phosphorous, potassium and nitrate where higher in mature leaves. All pigments including chlorophyll, lutein and ß-carotene augmented at advanced maturity stage and were more concentrated in the red pigmented cultivar at both stages. Total polyphenols accumulated more densely in red Salanova, particularly in the microgreens stage; whereas, in green Salanova, the accumulation was significant but less pronounced in the mcirogreens stage. Chlorogenic acid, quercetin malonyl glucoside, rutin and coumaroyl quinic acid were the most concentrated phenolic acids in microgreens, while feruloyl tartaric acid was predominant in mature leaves. Finally, when a high carotenoids content is sought, mature lettuce leaves should be the prime culinary choice, whereas high polyphenolic content is dictated by both the cultivar and the harvest stage, with red Salanova microgreens being the most nutrient-packed choice.

Geo-mineralogical characterisation of Mars simulant MMS-1 and appraisal of substrate physico-chemical properties and crop performance obtained with variable green compost amendment rates.

The configuration of a biologically fertile substrate for edible plant growth during long-term manned missions to Mars constitutes one of the main challenges in space research. Mars regolith amendment with compost derived from crew and crop waste in bioregenerative life support systems (BLSS) may generate a substrate able to extend crew autonomy and long-term survival in space. In this context, the aim of our work was threefold: first, to study the geochemistry and mineralogy of Mojave Mars Simulant (MMS-1) and the physico-chemical and hydraulic properties of mixtures obtained by mixing MMS-1 and green compost at varying rates (0:100, 30:70, 70:30, 100:0; v:v); secondly, to evaluate the potential use of MMS-1 as a growing medium of two lettuce (Lactuca sativa L.) cultivars; thirdly, to assess how compost addition may impact on sustainability of space agriculture by exploiting in situ resources. MMS-1 is a coarse-textured alkaline substrate consisting mostly of plagioclase, amorphous material and secondarily of zeolite, hematite and smectites. Although it can be a source of nutrients, it lacks organic matter, nitrogen, phosphorus and sulphur, which may be supplied by compost. Both cultivars grew well on all mixtures for 19 days under fertigation. Red Salanova lettuce produced a statistically higher dry biomass, leaf number and area than Green Salanova. Leaf area and plant dry biomass were the highest on 30:70 simulant:compost mixture. Nevertheless, the 70:30 mixture was the best substrate in terms of pore-size distribution for water-plant relationship and the best compromise for plant growth and sustainable use of compost, a limited resource in BLSS. Many remaining issues warrant further investigation concerning the dynamics of compost production, standardisation of supply during space missions and representativeness of simulants to real Mars regolith.

Distribution of primary and secondary metabolites among the leaf layers of headed cabbage (Brassica oleracea var. capitata).

The present study investigated the distribution of several primary metabolites (soluble sugar, protein, and mineral) and secondary metabolites (carotenoids, vitamin C, anthocyanin, flavonoids, and total phenolic compounds) among the leaf layers of headed cabbage. The leaf layers of two cultivars were separated and numbered sequentially from the outer to the inner leaves. The fructose and glucose content of the inner leaf layers was significantly greater than that of the outer layers. Similarly, the level of glucosinolates increased gradually from the outer leaves to the umbilicus of the leaf head. However, the content of antioxidants decreased from the outer leaves to the core of the leaf head, in line with the antioxidant capacity. The levels of soluble protein and mineral shared the similar decreasing trend. These results provide a reference for consumers to choose optimal fractions of whole cabbage heads in order to cater to their particular dietary needs.

Microencapsulation by spray-drying of polyphenols extracted from red chicory and red cabbage: Effects on stability and color properties.

The research of antioxidants and natural pigments to replace synthetic molecules is increasingly considering wastes from plant food supply chains. Red chicory (RCH) and red cabbage (RCA) are rich sources of polyphenols (PP), especially anthocyanins, well know natural pigments possessing strong antioxidant capacity and beneficial health effects. The aim of this work was to compare different solvents for PP extraction and to evaluate the effect of spray-drying encapsulation using modified starch on PP, antioxidant capacity (AOC) and color properties. Methanol:water (70:30) showed the best extraction capacity, while ethanol:water (70:30) extracts displayed the highest thermal stability. Ethanol:water extracts were spray-dried with a yield of 95-99% for both crops, while the efficiency of PP encapsulation was 79% (RCA) and 88% (RCH). Encapsulation improved retention of PP and AOC upon thermal treatment (RCH: 20-30%, RCA: 44-55%) without altering color properties. This process can be employed for the development of functional foods and supplements.

Genome-Wide Analysis of Basic Helix-Loop-Helix Superfamily Members Reveals Organization and Chilling-Responsive Patterns in Cabbage (Brassica oleracea var. capitata L.).

Basic helix-loop-helix (bHLH) transcription factor (TF) family is commonly found in eukaryotes, which is one of the largest families of regulator proteins. It plays an important role in plant growth and development, as well as various biotic and abiotic stresses. However, a comprehensive analysis of the bHLH family has not been reported in Brassica oleracea. In this study, we systematically describe the BobHLHs in the phylogenetic relationships, expression patterns in different organs/tissues, and in response to chilling stress, and gene and protein characteristics. A total of 234 BobHLH genes were identified in the B. oleracea genome and were further clustered into twenty-three subfamilies based on the phylogenetic analyses. A large number of BobHLH genes were unevenly located on nine chromosomes of B. oleracea. Analysis of RNA-Seq expression profiles revealed that 21 BobHLH genes exhibited organ/tissue-specific expression. Additionally, the expression of six BobHLHs (BobHLH003, -048, -059, -093, -109, and -148) were significantly down-regulated in chilling-sensitive cabbage (CS-D9) and chilling-tolerant cabbage (CT-923). At 24h chilling stress, BobHLH054 was significantly down-regulated and up-regulated in chilling-treated CS-D9 and CT-923. Conserved motif characterization and exon/intron structural patterns showed that BobHLH genes had similar structures in the same subfamily. This study provides a comprehensive analysis of BobHLH genes and reveals several candidate genes involved in chilling tolerance of B. oleracea, which may be helpful to clarify the roles of bHLH family members and understand the regulatory mechanisms of BobHLH genes in response to the chilling stress of cabbage.

Genome-wide characterization and expression profiling of SWEET genes in cabbage (Brassica oleracea var. capitata L.) reveal their roles in chilling and clubroot disease responses.

BACKGROUND: The SWEET proteins are a group of sugar transporters that play a role in sugar efflux during a range of biological processes, including stress responses. However, there has been no comprehensive analysis of the SWEET family genes in Brassica oleracea (BoSWEET), and the evolutionary pattern, phylogenetic relationship, gene characteristics of BoSWEET genes and their expression patterns under biotic and abiotic stresses remain largely unexplored. RESULTS: A total of 30 BoSWEET genes were identified and divided into four clades in B. oleracea. Phylogenetic analysis of the BoSWEET proteins indicated that clade II formed first, followed by clade I, clade IV and clade III, successively. Clade III, the newest clade, shows signs of rapid expansion. The Ks values of the orthologous SWEET gene pairs between B. oleracea and Arabidopsis thaliana ranged from 0.30 to 0.45, which estimated that B. oleracea diverged from A. thaliana approximately 10 to 15 million years ago. Prediction of transmembrane regions showed that eight BoSWEET proteins contain one characteristic MtN3_slv domain, twenty-one contain two, and one has four. Quantitative reverse transcription-PCR (qRT-PCR) analysis revealed that five BoSWEET genes from clades III and IV exhibited reduced expression levels under chilling stress. Additionally, the expression levels of six BoSWEET genes were up-regulated in roots of a clubroot-susceptible cabbage cultivar (CS-JF1) at 7 days after inoculation with Plasmodiophora brassicae compared with uninoculated plants, indicating that these genes may play important roles in transporting sugars into sink roots associated with P. brassicae colonization in CS-JF1. Subcellular localization analysis of a subset of BoSWEET proteins indicated that they are localized in the plasma membrane. CONCLUSIONS: This study provides important insights into the evolution of the SWEET gene family in B. oleracea and other species, and represents the first study to characterize phylogenetic relationship, gene structures and expression patterns of the BoSWEET genes. These findings provide new insights into the complex transcriptional regulation of BoSWEET genes, as well as potential candidate BoSWEET genes that promote sugar transport to enhance chilling tolerance and clubroot disease resistance in cabbage.