A group of nine species -now included in Brassica— differ from all the other species in several characters, mainly in the stylar portion of their pistils always without seed primordia. Also in their branched subterranean stem (caudex) with several leaf rosettes, their leaves entire to deeply pinnatifid but never pinnatisect, their shallowly notched cotyledons and their flattened, elliptic or ovoid seed contour. It is suggested to include these species under the generic denomination Guenthera Andr, in Bess. New ñames for the species and subspecies are provided, as well as a determination key for the species.

Population dynamics studies in Erucastrum nasturtiifolium (Poiret) O. E. Schulz (Brassicaceae) in relation to management and crop system in non-irrigated crops shown that E. nasturtiifolium populations remain stable in intensive cereals and cerealrotations because of the high survivorship and fecundity at low disturbance levels. In contrast, E. nasturtiifolium populations tend to extinction in vineyards because of the seed bank reduction provoked by continued emergence and high seedling mortality at high level of disturbances. | El estudio de la dinámica de poblaciones de E. nasturtiifolium (Poiret) O. E. Schulz (Brassicaceae) en los hábitats agrícolas en relación con el tipo de cultivo y manejo ha permitido constatar que en cultivos con baja frecuencia de perturbaciones, como la rotación cereal-barbecho o el monocultivo de cereal, las poblaciones de E. nasturtiifolium permanecen estables gracias a la elevada tasa de supervivencia y fecundidad de los individuos. Sin embargo, en cultivos con una elevada frecuencia de las perturbaciones, como la viña, las poblaciones tienden a la extinción a causa de la reducción del banco de semillas provocada por las continuas emergencias y la elevada mortalidad de las plántulas.

Pollen morphology of 7 species of the genus Alyssum belonging to thefamily Brassicaceae have been examined by light microscope. Pollen grains areusually isopolar; tricolpate with reticulate tectum. It is a stenopalynous genus.However, the species of this genus show little variation in shape, size colpilength and exine pattern. Hence the palynological characters are significant atspecific level.

Abstract Pathogen attack is a serious problem in rice, which is one of the most economically important crops worldwide. Plant genes with disease resistance have been extensively analyzed. Antimicrobial peptides from a variety of organisms are known to inhibit the growth of pathogens. Antimicrobial peptides are usually small, cationic, and amphipathic and have open-chain forms with disulfide bonds leading to rigid and compact structures. A gene family of plant defensins (AFP) is conserved in several plant species, including those of the Brassicaceae, and does not appear to be toxic to mammalian and plant cells. Rice plants do not contain these peptides. AFP1 homologs in 8 Brassicaceae vegetables have been identified, and their structural differences have been determined. AFP1 gene variants from Brassica oleracea and B, campestris conferred an effective resistance to both rice blast and bacterial leaf blight. The results of in vitro and in vivo analyses suggest that plant defensins have the potential to enhance broad-spectrum disease resistance in rice through genetic engineering. Modification of signal peptides and mature peptides could contribute to the improvement of broad disease resistance in crop plants, including rice.

Additional information is presented on the distribution of various exotic species of Brassicaceae, introduced recently to central Mexico. Three populations of Thlaspi arvense L. and Sinapis alba L. are reported. The species Diplotaxis muralis (L.) DC., Hirschfeldia incana (L.) Lagrèze-Fossat and Brassica tournefortii Gouan, known previously from northern Mexico, are now naturalized at various localities in the central part of the country. Rapistrum rugosum (L.) All., Cardamine hirsuta L., Lepidium latifolium L. and Lepidium draba L. (= Cardaria draba (L.) Desv.) are expanding in the Valley of Mexico and some neighboring regions. | Se presenta información adicional sobre la distribución de varias especies exóticas de Brassicaceae de reciente introducción en el centro de México. Se registran tres poblaciones de Thlaspi arvense L. y de Sinapis alba L. Las especies Diplotaxis muralis (L.) DC., Hirschfeldia incana (L.) Lagrèze-Fossat y Brassica tournefortii Gouan, conocidas previamente del norte de México, ahora están naturalizadas y al parecer en expansión en varias localidades en el centro del país. Rapistrum rugosum (L.) All., Cardamine hirsuta L., Lepidium latifolium L. y Lepidium draba L. (= Cardaria draba (L.) Desv.) están extendiéndose en el Valle de México y algunas regiones vecinas.

Investigations of the effects of two global events – elevated CO₂ levels and enhanced ultraviolet-B (UV-B) radiation – on floral nectar production are reviewed from twelve dicotyledonous families. Furthermore, to allow comparisons between nectary morphology and nectar production in treated plants of these fifteen species, new data on floral nectary structure are provided for Malcolmia maritima (L.) R. Br. (Brassicaceae) and Scabiosa columbaria L. (Dipsacaceae). All but the last taxon possessed mesenchymatic floral nectaries with surface stomata. Few clear relationships existed between nectary morphology and various physiological responses to CO₂ or UV-B enrichment, indicating that species responded notwithstanding nectary structure itself. Overall, nectar-solute concentration was least affected by elevated CO₂ or UV-B radiation; consequently, changes in nectar volume were responsible for differences in nectar-sugar production per flower. Three species of Fabaceae experienced no change in floral nectar production upon exposure to elevated CO₂. To date, no study of enhanced UV-B radiation reported a consistent reduction in floral nectar production; three species of Brassicaceae responded differently, but various levels of ozone depletion were simulated. Experimentation with more taxa – including those possessing nectary types such as septal (gynopleural) nectaries (e.g. many monocotyledons) or aggregations of glandular trichomes – and expanding such physiological studies to species possessing extrafloral nectaries, are recommended.

Camelina microcarpa (Brassicaceae) is a spring or winter annual weed. The paper deals with determination, distribution and description of habitats where its species usually occur in Slovakia. Two subspecies, C. microcarpa subsp. microcarpa and C. microcarpa subsp. sylvestris, were revised in the territory of Slovakia. Most localities are in Danube lowland and western part of Slovakia, but subsp. sylvestris is sparsely spread in many other Slovak regions. Migration of both subspecies from ruderal to xerothermic grassland habitats was detected. The key for determination of particular subspecies, their description, characteristic habitats and maps of distribution of both subspecies in Slovakia are given.

Glucosinolate content of leaves and roots, diversity in leaf pubescence, and resistance to two near-isogenic lines of the flea beetle Phyllotreta nemorum with or without an R-gene, were determined for 27 accessions of 7 Barbarea taxa, i.e. B. stricta, B. orthoceras, B. intermedia, B. verna, B. vulgaris var. vulgaris, the G-type of B. vulgaris var. arcuata and the P-type of B. vulgaris var. arcuata. Four variable glucosinolate biosynthetic characters were deduced. For (formally) homophenylalanine-derived glucosinolates: (1) Presence or absence of 2-hydroxylation, and if present, R- or S-configuration of 2-hydroxylation; (2) presence or absence of p-hydroxylation; and for tryptophan-derived glucosinolates: (3) presence or absence of N-methoxyglucobrassicin; and (4) presence or absence of 1,4-dimethoxyglucobrassicin. Three phenotypes of leaf-pubescence were observed; (1) glabrous to glabrate leaves; (2) glabrous to glabrate leaves with hairs along the edge; (3) pubescent leaves. The hairs were characterized as simple by scanning electron microscopy. Full resistance to a flea beetle line (ST) was found in B. vulgaris var. vulgaris and in the G-type of var. arcuata; partial resistance was found in B. verna and B. intermedia, while the remaining taxa were fully susceptible to the ST line. All investigated Barbarea taxa were susceptible to larvae from another line containing an R-gene, indicating a similar flea beetle resistance mechanism in the three resistant species. Most Barbarea taxa could be characterized by a particular combination of the investigated characters. The most aberrant was the P-type of B. vulgaris var. arcuata, and the taxonomic status of this type should be reconsidered.

Of the plant self-incompatibility (SI) systems investigated to date, that possessed by members of the Brassicaceae is currently the best understood. Whilst the recent demonstrations of interactions between the male determinant (S-locus cysteine rich protein, SCR) and the female determinant (S-locus receptor kinase, SRK) indicate the minimal requirement for SI in Brassica, no consensus exists as to the nature of these molecules in vivo and the potential involvement of accessory molecules in establishing the active S-receptor complex. Variation between S haplotypes appears to be present in the molecular composition of the receptor complex, the regulation of downstream signalling and the requirement for accessory molecules. This review discusses what constitutes an active receptor complex and highlights potential differences between haplotypes. The role of accessory molecules, in particular SLG (S-locus glycoprotein) and low molecular weight pollen coat proteins (PCPs), in pollination are discussed, as is the link between SI and unilateral incompatibility (UI).