A new Sparassis species from Spain described using morphological and molecular data

Sparassis miniensis, collected in Pinus pinaster forests in Galicia (northwest Iberian Peninsula) is described as a new species, based on morphological and molecular data. Sparassis miniensis is morphologically distinct from all other species in the genus Sparassis based on scattered flabellae, which are strongly laciniated, azonate, and arise from an orange to rose-purplish base. The sporadic presence of clamp connections is restricted to subhymenial hyphae. Molecular data from LSU-rDNA, ITS and partial gene coding RNA polymerase subunit II (rpb2) suggest a close relationship between the new species S. miniensis and S. brevipes, another European species producing large fruiting bodies but with entire flabellae and no clamp connections.     

The phytoalexins from cauliflower, caulilexins A, B and C: isolation, structure determination, syntheses and antifungal activity

Our continuous search for phytoalexins from crucifers led us to examine phytoalexin production in florets of cauliflower (Brassica oleracea var. botrytis) under abiotic (UV light) elicitation. Four known (isalexin, S-(-)-spirobrassinin, 1-methoxybrassitin, brassicanal C) and three new (caulilexins A-C) phytoalexins were isolated. The syntheses and antifungal activity of caulilexins A-C against the economically important pathogenic fungi Leptosphaeria maculans, Rhizoctonia solani and Sclerotinia sclerotiorum, and the first synthesis of brassicanal C are reported.     

beta-Carotene accumulation induced by the cauliflower Or gene is not due to an increased capacity of biosynthesis

The cauliflower (Brassica oleracea L. var. botrytis) Or gene is a rare carotenoid gene mutation that confers a high level of beta-carotene accumulation in various tissues of the plant, turning them orange. To investigate the biochemical basis of Or-induced carotenogenesis, we examined the carotenoid biosynthesis by evaluating phytoene accumulation in the presence of norflurazon, an effective inhibitor of phytoene desaturase. Calli were generated from young seedlings of wild type and Or mutant plants. While the calli derived from wild type seedlings showed a pale green color, the calli derived from Or seedlings exhibited intense orange color, showing the Or mutant phenotype. Concomitantly, the Or calli accumulated significantly more carotenoids than the wild type controls. Upon treatment with norflurazon, both the wild type and Or calli synthesized significant amounts of phytoene. The phytoene accumulated at comparable levels and no major differences in carotenogenic gene expression were observed between the wild type and Or calli. These results suggest that Or-induced beta-carotene accumulation does not result from an increased capacity of carotenoid biosynthesis.     

Transformation by T-DNA integration causes highly sterile phenotype independent of transgenes in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Agrobacterium tumefaciens-mediated gene transformation caused highly sterile phenotype in T1 transgenic populations of Arabidopsis thaliana. The phenomenon occurred independent of the genes and construct types used for transformation. The occurring frequency is less than 10% and the phenotype is inheritable. Intensive examination elucidated that the sterility is due to indehiscence or delayed dehiscence of the anthers during the flowering stage, resulting from the reduced or disordered endothecial secondary wall thickening of the anthers in the sterile flowers. Exogenous jasmonic acid application cannot rescue the sterile phenotype. Additionally, by using the Escherichia coli uidA gene encoding the beta-glucuronidase as a reporter gene, we indicated that the Cauliflower mosaic virus 35S promoter was not constitutively active as expected previously in the reproductive organs of Arabidopsis. These results contribute significantly to the plant community by suggesting that more careful examination and statistical analysis are needed while studying gain-of-function phenotypes of genes, especially for genes that might be involved in reproductive development.     

Preliminary analysis of the cauliflower mitochondrial proteome

Purified cauliflower (Brassica oleracea var. botrytis) mitochondrial proteins fractionated into soluble, membrane, integral membrane and peripheral membrane samples were analyzed by 2D- PAGE (isoelectric focusing/ SDS polyacrylamide gel electrophoresis). 2D gels patterns were compared using the Imager Master 2D Elite software. 561 silver stained protein spots were resolved after electrophoresis under standard conditions of a whole protein extract. In the soluble fraction a prevalent number of more intense protein spots was observed. The cauliflower protein 2D patterns resembled Arabidopsis thaliana 2D patterns. The two protein spots selected which occupied a similar isoelectric point positions on both gels represented the same proteins as revealed by ESI-MS analysis of cauliflower proteins. The third selected spot belongs to unidentified proteins. The comparative analysis of mitochondrial suborganellar fractions proved the usefulness of this approach.     

Multilocus genotyping of a ‘Candidatus Phytoplasma aurantifolia’‐related strain associated with cauliflower phyllody disease in China

A new cauliflower disease characterised by the formation of leaf‐like inflorescences and malformed flowers occurred in a seed production field located in Yunnan, a southwest province of China. Detection of phytoplasma‐characteristic 16S rRNA gene sequences in DNA samples from diseased plants linked the cauliflower disease to phytoplasmal infection. Results from phylogenetic and virtual restriction fragment length polymorphism analyses of the 16S rRNA gene sequence indicated that the cauliflower‐infecting agent is a ‘Candidatus Phytoplasma aurantifolia’‐related strain and is a new member of the peanut witches'‐broom phytoplasma group, subgroup A (16SrII‐A). Multilocus genotyping showed close genetic relationship between this cauliflower phytoplasma and a broad host range phytoplasma lineage found only in East Asia thus far. Molecular markers present in the secY and rp loci distinguished this phytoplasma from other members of the subgroup 16SrII‐A.     

花椰菜花叶病毒(新疆分离物)基因组DNA的全部核苷酸序列

用Maxam-Gilbert化学切断法,从含全长病毒DNA的克隆pCaMV C17中,测定了CaMV-XJ基因组的全部核苷酸序列。CaMV-XJ DNA含有8,060个碱基对。在不同的译读相位中,CaMV基因组含有6个主要ORF或可能的基因,与其他巳作全序列测定的三个CaMV分离物比较,有三个显著的差别;(1)ORFⅥ编码的氨基酸变化达16％,显著高于其他区域的变化和其他三个分离物之间的差别,(2)在ORFⅣ的近氨基末端有39bp的插入,它与被插入区的序列几乎是直接重复;(3)由于核苷酸置换而引入了终止信号,所以T.Hohn[2]推测,可能存在的ORFⅦ不可能编码有功能的蛋白。     

DNA transfer from Agrobacterium to Zea mays or Brassica by agroinfection is dependent on bacterial virulence functions

Summary DNA transfer fromAgrobacterium tumefaciens, a soil bacterium, to the non-host graminaceous monocotyledonous plantZea mays, was analysed using the recently developed technique of agroinfection. Agroinfection ofZ. mays with maize streak virus using strains ofA. tumefaciens carrying mutations in the pTiC58 virulence region showed an almost absolute dependence on the products of the bacterialvirC genes. In contrast, agroinfection of the control hostBrassica rapa with cauliflower mosaic virus was less dependent on thevirC gene products. In other respects, the basic mechanism of the plant-bacterium interaction was found to be similar. While intactvirA, B, D and G functions were absolutely necessary, mutants invirE were attenuated. Agroinfection of maize was effective in the absence of an exogenously suppliedvir gene inducer, and indeed woundedZ. mays tissues were found to produce substance(s) which induced the expression ofA. tumefaciens vir genes. These findings are discussed in the light of current knowledge about the function ofAgrobacterium vir genes.     

Development of insect-resistant transgenic cauliflower plants expressing the trypsin inhibitor gene isolated from local sweet potato

Agrobacterium-mediated transformation was used to introduce a trypsin inhibitor gene into Taiwan cauliflower (Brassica oleracea var. botrytis L.) cultivars. The TI gene was isolated from a well-adapted Taiwan sweet potato cultivar and was expected to be especially effective in combating local pests. In vitro regeneration studies indicated that 4-day-old cauliflower seedling hypocotyl segments, pretreated with 2,4-dichlorophenoxyacetic acid for 3 days and incubated on a silver-ion-containing shoot induction medium, gave regeneration rates greater than 95%. Optimum transformation conditions were determined. G418 selection at 15 mg/l was initiated 1 week after cocultivation, and the dose was doubled 1 week later. Over 100 putative transgenic plants were produced. Transgenic status was confirmed by in vitro TI activity, and Southern and Western hybridization assays. The transgenic plants demonstrated in planta resistance to local insects to which the control plants were vulnerable. Received: 21 July 1997 / Revision received: 27 February 1998 / Accepted: 16 March 1998     

Metabolic engineering of carotenoid accumulation by creating a metabolic sink

Carotenoids are highly beneficial for human nutrition and health because they provide essential nutrients and important antioxidants in our diets. However, many food crops, especially the major staple crops contain only trace to low amounts of carotenoids. Although significant progress has been made in developing food crops rich in carotenoids by altering the expression of carotenoid biosynthetic genes, in many cases it has proved to be difficult to reach the desired levels of carotenoid enrichment. The recent identification and characterization of a novel gene mutation in cauliflower reveals that creating a metabolic sink to sequester carotenoids is an important mechanism to control carotenoid accumulation in plants. The successful demonstration of increased carotenoid accumulation in association with the formation of sink structures in transgenic crops offers a new and alternative approach to increase carotenoid content. Manipulation of the formation of metabolic sink along with the catalytic activity of the pathway may represent a promising strategy for maximally improving the nutritional quality of food crops.