Novel morphological structures allowed adaptation to dry conditions in early land plants. The cuticle, one such novelty, plays diverse roles in tolerance to abiotic and biotic stresses and plant development. Cuticular waxes represent a major constituent of the cuticle and are comprised of an assortment of chemicals that include, among others, very long chain fatty acids (VLCFAs). Members of the β-ketoacyl coenzyme A synthases (KCS) gene family code for enzymes that are essential for fatty acid biosynthesis. The gene KCS6 (CUT1) is known to be a key player in the production of VLCFA precursors essential for the synthesis of cuticular waxes in the model plant Arabidopsis thaliana (Brassicaceae). Despite its functional importance, relatively little is known about the evolutionary history of KCS6 or its paralog KCS5 in Brassicaceae or beyond. This lacuna becomes important when we extrapolate understanding of mechanisms gained from the model plant to its containing clades Brassicaceae, flowering plants, or beyond. The Brassicaceae, with several sequenced genomes and a known history of paleoploidy, mesopolyploidy and neopolyploidy, offer a system in which to study the evolution and diversification of the KCS6-KCS5 paralogy. Our phylogenetic analyses across green plants, combined with comparative genomic, microsynteny and evolutionary rates analyses across nine genomes of Brassicaceae, reveal that (1) the KCS6-KCS5 paralogy arose as the result of a large segmental duplication in the ancestral Brassicaceae, (2) the KCS6-KCS5 lineage is represented by a single copy in other flowering plant lineages, (3) the duplicated segments undergo different degrees of retention and loss, and (4) most of the genes in the KCS6 and KCS5 gene blocks (including KCS6 and KCS5 themselves) are under purifying selection. The last also true for most members of the KCS gene family in Brassicaceae, except for KCS8, KCS9 and KCS17, which are under positive selection and may be undergoing functional evolution, meriting further investigation. Overall, our results clearly establish that the ancestral KCS6/5 gene duplicated in the Brassicaceae lineage. It is possible that any specialized functions of KCS5 found in Brassicaceae are either part of a set of KCS6/5 gene functions in the rest of the flowering plants, or unique to Brassicaceae.

PREMISE OF THE STUDY: Nearly all seed plants rely on stored seed reserves before photosynthesis can commence. Natural selection for seed oil traits must have occurred over 319 million years of evolution since the first seed plant ancestor. Accounting for the biogeographic distribution of seed oil traits is fundamental to understanding the mechanisms of adaptive evolution in seed plants. However, the evolution of seed oils is poorly understood. We provide evidence of the adaptive nature of seed oil traits at the intraspecific and interspecific levels in Brassicaceae—an oilseed‐rich and economically important plant family. METHODS: Univariate statistics, Pearson's correlation, multiple regression, generalized linear mixed model analysis, and phylogenetic autocorrelation tests on seed oil traits of 360 accessions of Arabidopsis thaliana and 216 Brassicaceae species helped provide evidence of the adaptive nature of seed oil traits. KEY RESULTS: At higher latitudes, both seed oil content and unsaturated fatty acids have selective advantages in Arabidopsis thaliana (intraspecific‐level), while only unsaturated fatty acids have selective advantages across 216 Brassicaceae species (interspecific‐level). The seed oil patterns fit within the theoretical framework of the gradient model. Seed oil content increases significantly from temperate to subtropical to tropical regions in Brassicaceae herbs. Absence of phylogenetic signals for seed oil traits and high seed oil content in four tribes of Brassicaceae were observed. CONCLUSIONS: Multiple seed oil traits are adaptive in nature and follow a gradient model. Consistent evolutionary patterns of seed oil traits were observed at the intraspecific and interspecific levels in Brassicaceae. Seed oil traits change with latitude and across biomes, suggesting selection. The absence of a phylogenetic signal for seed oil traits and the occurrence of high seed oil content in four Brassicaceae tribes provides evidence of the adaptive nature of seed oil traits in Brassicaceae.

In last decades, when many diseases were associated to lifestyle, especially to food quality, researcher attention was guided to find alternative sources in nature. Nowadays, a large range of crops have been identified to play an important role in different industries as follows: food, pharmaceutics, cosmetics, medicinal, etc. Species from Brassicaceae family are considered to be valuable resources thanks to their nutritional quality. The chemical content of Brassicaceae species allows usage of entire plants or different organs, as raw material for multiple purposes. The aim of this paper was to present a part of Romanian Brassicaceae genetic resources in order to highlight the enormous potential of species to be used as medicinal. The paper presents a list of spontaneous and cultivated Brassicaceae in North East region of Romania, used as medicinal, and provides information about their traditional medicinal use. A number of 21 spontaneous Brassicaceae were identified in wild flora, and they are currently used as medicinal. In the investigated region, Brassicaceae species are cultivated mainly for their use as vegetables and spices. Species as Brassica nigra, Lepidium sativum, Nasturtium officinale, Raphanus sativus var. niger and Sinapis alba L. are also cultivated for their medicinal use. For these species we also presented information related to their yield potential.

KEY MESSAGE: Epigenetic dominance modifier. In polymorphic loci, complex genetic dominance relationships between alleles are often observed. In plants, control of self-incompatibility (SI) expression via allelic interactions in the Brassicaceae is the best-known example of such mechanisms. Here, with emphasis on two recently published papers, we review the progress toward understanding the dominance regulatory mechanism of SI in the Brassicaceae. Multiple small RNA genes linked to the Self-incompatibility (S) locus were found in both Brassica and Arabidopsis genera. Mono-allelic gene expression of the male determinant of SI, SP11/SCR, from a dominant S-allele is under epigenetic control by such small RNA genes. Possible evolutionary trajectories leading to the formation of multilayered dominance hierarchy in Brassicaceae are discussed. We also identify some remaining questions for future studies.

Plants emit characteristic organic volatile compounds (VOCs) with diverse biological/ecological functions. However, the links between plant species/varieties and their phytochemical emission profiles remain elusive. Here, we developed a direct headspace solid-phase microextraction (HS-SPME) technique and combined with non-targeted gas chromatography‒high-resolution mass spectrometry (GC-HRMS) platform to investigate the VOCs profiles of 12 common Brassicaceae vegetables (watercress, rocket, Brussels sprouts, broccoli, kai lan, choy sum, pak choi, cabbage, Chinese cabbage, cauliflower, radish and cherry radish). The direct HS-SPME sampling approach enabled reproducible capture of the rapid-emitting VOCs upon plant tissue disruption. The results revealed extensive variation in VOCs profiles among the 12 Brassicaceae vegetables. Furthermore, principal component analysis (PCA) showed that the VOC profiles could clearly distinguish the 12 Brassicaceae vegetables, and that these profiles well reflected the classical morphological classification. After multivariate statistical analysis, 44 VOCs with significant differences among the Brassicaceae vegetables were identified. Pathway analysis showed that three secondary metabolism pathways, including the fatty acid pathway, methylerythritol phosphate (MEP) pathway and glucosinolate (GLS) pathway, behave distinctively in these vegetables. These three pathways are responsible for the generation and emission of green leaf volatiles (GLVs), terpenes and isothiocyanates (ITCs), respectively. Correlation analysis further showed that volatile metabolites formed via the common pathway had significantly positive correlations, whereas metabolites from different pathways had either non-significant or significantly negative correlations. Genetic influences on these metabolites across various vegetable types were also evaluated. These findings extend our phytochemical knowledge of the 12 edible Brassicaceae vegetables and provide useful information on their secondary metabolism.

Cover and biofumigant crops of Brassicaceae are potential alternatives to synthetically-derived nematicides for managing root-knot nematode pests in various crops. The host status of Eruca sativa (cvs. Rocket Trio and Nemat), Brassica juncea (cvs Calienté and Fumigreen) and Raphanus sativus (cvs Doublet and Terranova) were determined for Meloidogyne incognita and Meloidogyne javanica in separate glasshouse experiments. Additionally, the efficacy of such cover- and biofumigant crops (after incorporation of their aerial parts) was evaluated against root-knot nematode populations at two field sites (potato and tomato, respectively). All cover crops evaluated in the glasshouse showed resistance against both Meloidogyne spp., except B. juncea cv. Calienté to M. incognita. None of the Brassicaceae crops used in the potato study, however, resulted in a significant reduction of population levels of M. incognita in roots and tubers of the Brassicaceae in the follow-up potato crop. In contrast, only cv. Nemat reduced Meloidogyne spp. population densities significantly in tomato roots, while cvs Doublet, Terranova and Rocket Trio reduced population densities substantially. Plant-growth parameters, viz. plant length and mass as well as yield (fruit mass and number of fruits harvested) were significantly higher for tomato grown in plots where cvs. Doublet and Rocket Trio grew and their aerial parts incorporated. Although variable, Brassicaceae cvs evaluated showed potential as an alternative management strategy against root-knot nematodes.

The genus Aethionema is sister to the core Brassicaceae (including Arabidopsis thaliana) and thus has an important evolutionary position for comparative analyses. Aethionema arabicum (Brassicaceae) is emerging as a model to understand the evolution of various traits. We generated transcriptome data for seven Ae. arabicum genotypes across the species range including Cyprus, Iran and Turkey. Combined flow cytometry and single nucleotide polymorphism (SNP) analyses identified distinct tetraploid (Iranian) and diploid populations (Turkish/Cypriot). The Turkish and Cypriot lines had a higher genome-wide genetic diversity than the Iranian lines. However, one genomic region contained genes with a higher diversity in the Iranian than the Turkish/Cypriot lines. Sixteen percent of the genes in this region were chaperonins involved in protein folding. Additionally, an analysis of glucosinolate profiles, chemical defence compounds of the Brassicaceae, showed a difference in diversity of indolic glucosinolates between the Iranian and Turkish/Cypriot lines. We showed that different Ae. arabicum individuals have different ploidy levels depending on their location (Iranian versus Turkish/Cypriot). Moreover, these differences between the populations are also shown in their defence compounds.

Crambe abyssinica is an important oilseed crop that accumulates high levels of erucic acid, which is being recognized as a potential oil platform for several industrial purposes. It belongs to the family Brassicaceae, assigned within the tribe Brassiceae. Both family and tribe have been the subject of several phylogenetic studies, but the relationship between some lineages and genera remains unclear. Here, we report the complete sequencing and characterization of the C. abyssinica plastome. Plastome structure, gene order, and gene content of C. abyssinica are similar to other species of the family Brassicaceae. The only exception is the rps16 gene, which is absent in many genera within the family Brassicaceae, but seems to be functional in the tribe Brassiceae, including C. abyssinica. However, the analysis of gene divergence shows that the rps16 is the most divergent gene in C. abyssinica and within the tribe Brassiceae. In addition, species of the tribe Brassiceae also show similar SSR loci distribution, with some regions containing a high number of SSRs, which are located mainly at the single copy regions. Six hotspots of nucleotide divergence among Brassiceae species were located in the single copy regions by sliding window analysis. Brassicaceae phylogenomic analysis, based on the complete plastomes of 72 taxa, resulted in a well-supported and well-resolved tree. The genus Crambe is positioned within the Brassiceae clade together with the genera Brassica, Raphanus, Sinapis, Cakile, Orychophragmus and Sinalliaria. Moreover, we report several losses and gains of RNA editing sites that occurred in plastomes of Brassiceae species during evolution.

Crambe abyssinica is an important oilseed crop that accumulates high levels of erucic acid, which is being recognized as a potential oil platform for several industrial purposes. It belongs to the family Brassicaceae, assigned within the tribe Brassiceae. Both family and tribe have been the subject of several phylogenetic studies, but the relationship between some lineages and genera remains unclear. Here, we report the complete sequencing and characterization of the C. abyssinica plastome. Plastome structure, gene order, and gene content of C. abyssinica are similar to other species of the family Brassicaceae. The only exception is the rps16 gene, which is absent in many genera within the family Brassicaceae, but seems to be functional in the tribe Brassiceae, including C. abyssinica. However, the analysis of gene divergence shows that the rps16 is the most divergent gene in C. abyssinica and within the tribe Brassiceae. In addition, species of the tribe Brassiceae also show similar SSR loci distribution, with some regions containing a high number of SSRs, which are located mainly at the single copy regions. Six hotspots of nucleotide divergence among Brassiceae species were located in the single copy regions by sliding window analysis. Brassicaceae phylogenomic analysis, based on the complete plastomes of 72 taxa, resulted in a well-supported and well-resolved tree. The genus Crambe is positioned within the Brassiceae clade together with the genera Brassica, Raphanus, Sinapis, Cakile, Orychophragmus and Sinalliaria. Moreover, we report several losses and gains of RNA editing sites that occurred in plastomes of Brassiceae species during evolution.

Rūrāne I., Evarts-Bunders P., Nitcis M., 2018: Distribution trends of some species of the Brassicaceae family in Latvia. - Botanica, 24(2): 124-131. The aim of this paper was to clarify and analyse the distribution trends of some Brassicaceae species (Bunias orientalis, Sisymbrium volgense, Barbarea arcuata, Draba nemorosa and Camelina alyssum) in Latvia. Field studies and the herbarium material analyses were carried out. The distribution trends were analysed by comparing all selected species in three time periods: by 1940, from 1941 to 1990, and from 1991 to the present. The study shows that the distribution of Brassicaceae species such as Bunias orientalis, Sisymbrium volgense, Barbarea arcuata and Draba nemorosa has increased significantly in Latvia during the time period from 1991 to the present, and these species are mostly found on railway, ruderal areas and roadsides, which are important habitats for species distribution. The occurrence of Camelina alyssum has considerably declined or perhaps the species has even disappeared from the flora of Latvia, which has been affected greatly by changes in the cultivation of agricultural crops as well as in agricultural land management.