We obtained 16 nucleotide sequences (approximately l400 bp each) of the first intron of the mitochondrial (mt) gene for NADH subunit 4 (nad4) from 10 species of Brassicaceae. Using these new sequences and five published sequences from GenBank, we constructed a phylogenetic tree of the Brassicaceae species under study and showed that the rate of nucleotide substitution in the first intron of nad4 is very low, about 0.16-0.23 x 10(-9) substitution per site per year, which is about half of the silent rate in exons of nad4. The ratios of substitution rates in this intron, ITS, and IGS are approximately 1:23:73, where ITS is the nuclear intergenic spacer between 18S and 25S rRNA genes and IGS is the intergenic spacer of 5S rRNA genes. A segment (335 bp) in the first intron of nad4 in Brassicaceae species that is absent in wheat was considered as a nonfunctional sequence and used to estimate the neutral rate (the rate of mutation) in mtDNA to be 0.5-0.7 x 10(-9) substitution per site per year, which is about three times higher than the substitution rate in the rest of the first intron of nad4. We estimated that the dates of divergence are 170-235 million years (Myr) for the monocot-dicot split, 112-156 Myr for the Brassicaceae-Lettuce split, 14.5-20.4 Myr for the Brassica-Arabidopsis split, and 14.5-20.4 Myr for the Arabidopsis-Arabideae split.

The significance of tocopherols as chemotaxonomic markers and their relationship with oil content and fatty acid profile was investigated in a collection of 91 species of the family Brassicaceae. Total tocopherols content ranged from 68 mg kg(-1) oil in Diplotaxis viminea to 2479 mg kg(-1) oil in Schivereckia doerfleri. The collection also showed wide variability for tocopherol composition. The average tocopherol profile consisted of 65.4% (gamma-), 28.7% (alpha-), 5.1% (delta-) and 0.8% beta-tocopherol. Individual tocopherols were found to have great taxonomic value in the Brassicaceae.

The DNA and deduced amio acid sequences of the 2S albumin seed storage protein genes from some members of the Brassicaceae, including the genera Brassica, Raphanus, Sinapis (all tribe Brassiceae) and Arabidopsis (tribe Sysimbrieae), were analysed to infer their phylogenetic relationships. Analysis of the DNA sequence of the 5' and 3' untranslated flanking regions provided evidence that a number of the 2S albumin genes were duplicated prior to the Brassiceae-Sysimbrieae split. Analysis of the deduced amino acid sequence of the protein coding regions suggested that many of these sequences have undergone concerted evolution. Three distinct clusters of 2S albumin genes were identified within the Brassiceae; one cluster consisted entirely of Sinapis sequences, the second cluster consisted of sequences from B. oleracea, and B. juncea and some sequences from B. napus, and the third cluster consisted of sequences from B. rapa, B. nigra, R. sativus, and the remaining B. napus sequences. Comparison of the gene tree of the coding regions with a conventional species tree suggests that the protein coding sequences in the latter two clusters were created by duplication and subsequent divergence in the common ancestor of these species, and that sequences derived from one of the clusters have been eliminated from the genome of each species. These results suggest that both gene duplication and non-reciprocal DNA exchanges have played a role in the evolution of the 2S albumin genes of the Brassicaceae.

The subantarctic Brassicaceae Pringlea antiscorbutica R. Br. (Kerguelen cabbage) was used as a model to study the physiological adaptations of higher plants to the subantarctic environment. ¹³C-nuclear magnetic resonance permitted, in combination with biochemical methods, the identification and quantification of the major solutes in leaves, stem and roots. As characterized in many Brassicaceae, proline was a major solute in all organs of the plants, and its accumulation was mainly controlled by salt stress rather than temperature. Glucose was the major soluble sugar in the leaves, whilst sucrose and starch accumulated in stems and roots. Over a period of 1 year we found strong correlations between (i) glucose content in leaves and irradiance, and (ii) starch content in non-photosynthetic organs and air temperature. The pattern of carbohydrate accumulation indirectly indicated that photosynthetis was sustained throughout the year, even during cold days when the temperature remained near 0 °C. This is consistent with the direct gas exchange measurements showing that photosynthetic capacity is mainly influenced by irradiance and weakly by temperature. Taken together, these characteristics demonstrated that the growth and development cycle occurs without a period of dormancy.

In 1996-1998 in Vezaiciai Branch of the Lithuanian Institute of Agriculture the research on weed species diversity in oat, beetroot and barley stands was carried out. 22 species of weeds, belonging to 12 families were found. Aseraceae, Brassicaceae and Caryophyllaceae families were most abundant. About 90-230 weeds were in a squaer metre. Viola arvensis and Spergula arvensis dominated

Proline is one of the major solutes accumulated upon salt stress in leaves, stem and roots of the subantarctic Brassicaceae Pringlea antiscorbutica R. Br. (Kerguelen cabbage). Using in vivo¹³C-NMR techniques, it was possible for the first time to visualize the subcellular compartmentation of proline between cytoplasmic and vacuolar compartments in Pringlea leaves. We observed that this osmolyte accumulated at a 2-3 times higher concentration in the cytoplasm than in the vacuole.

During the Autumn 1997 serious epidemics of black rot of brassicas by Xanthomonas campestris pv. campestris occurred in Sicily. First symptoms of the disease were observed in sprinkle irrigated fields. During a survey in areas devoted to brassicas, on broccoli, cauliflower and kohlrabi a further spread of the disease was observed due to the wet weather and to optimum temperature conditions for the bacterium. The causal agent of the disease was isolated from symptomatic plant samples collected during the survey. The identification was performed by physiological, biochemical and pathogenicity tests. The results are discussed in relation to the biological and agronomical traits of brassicas grown in Sicily | Gravi episodi di marciume nero da Xanthomonas campestris pv. campestris si sono verificati in Sicilia nell'autunno 1997. I primi sintomi sono stati osservati a settembre nei campi irrigati per aspersione. Durante un'indagine svolta in aree interessate alla coltivazione di Brassicaceae, e' stata osservata un'ulteriore diffusione della malattia su broccolo, cavolfiore e cavolo rapa, a seguito delle abbondanti precipitazioni e dei livelli termici ottimali allo sviluppo del patogeno verificatisi durante il suddetto periodo. Dai campioni sintomatici prelevati durante l'indagine, l'agente della malattia e' stato isolato ed identificato mediante saggi biochimici e fisiologici ed inoculazioni in vivo. I risultati vengono presentati e discussi anche in relazione alle specificita' di ordine biologico (utilizzazione di cultivar locali e produzione del seme in azienda) ed agronomico (successione colturale pressoche' continua) che la Brassicaceae esprimono in Sicilia

Self-incompatibility (SI) is a widespread mechanism in angiosperms which prevents self-fertilization. This mechanism relies on cell-cell interactions between pollen and pistil. Among the different SI systems that have been reported, two have been particularly investigated: the gametophytic system of Solanaceae and the sporophytic system of Brassicaceae. In these two families, although the molecular bases of SI response are different, secreted and/or membrane-anchored proteins are required for self-pollen rejection. Interestingly, these proteins exhibit two functions: recognition and a catalytic activity. In this review article, we present recent advances which permit a better understanding of how these proteins control the male/female recognition event associated with the SI response

The myrosinase-glucosinolate system is one of the plant defense systems, which exists mainly in the Brassicaceae family. Myrosinase hydrolyzes glucosinolates into several products that some of them are toxic for certain herbivores. Some types of myrosinases form a high molecular complexes with other non-myrosinase proteins. One of these non-myrosinase proteins is Myrosinase-Associated Protein (MyAP), which is a 40 kD glycosilated protein with at least one intramolecular disulfide bridge. MyAP exists both in complex with myrosinase and in a free form. Based on its sequence similarity with other proteins with known activities, MyAP has been proposed to have an esterase activity. One of the cDNA of induced MyAP (iMyAP9) has been expressed in E. coli in the inclusion body fraction.