970 resultados para plant variety protection
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"February 1994."
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"May 2008."
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"October 1992."--Cover.
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"February 2001"--P. [2].
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"August 2002"--P. [2].
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Cover title.
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The polyphagous moth Helicoverpa armigera (Hubner) is one of the world's most important agricultural pests. A number of existing approaches and future designs for management of H. armigera rely on the assumption that moths do not exhibit either genetically and/or non-genetically based variation for host plant utilization. We review recent empirical evidence demonstrating that both these forms of variation influence host plant use in this moth. The significance of this variation in H. armigera in relation to current and future pest management strategies is examined. We provide recommendations on future research needs and directions for sustainable management of H. armigera, under a framework that includes consideration of intra.-specific variation for host use relevant in this and other similar pest species. (C) 2004 Elsevier Ltd. All rights reserved.
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Ecophysiological research in Australia has focussed, at different times, on the fundamental similarities in function between all plant species, and on the peculiarity of Australian species with respect to their survival in stressful environments. Early work on plant water relations emphasised the differences between species, and indicated that diverse structural and functional attributes occurred in species from the same water-limited environment. Most recent research has emphasised processes that optimise rates of carbon dioxide exchange, but the understanding of functioning in plants with different morphological arrangements is incomplete. Variation in functions between individual plants and geographic populations in wild species has been examined to a lesser extent. The great variety within and between populations of wild plant species warrants further study for both understanding and more effective management of this biological resource.
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The use of morphological data obtained from field (plot test) and glasshouse trials to identify and discriminate among four Iranian and two New Zealand lucerne (Medicago sativa L.) cultivars was investigated, following guidelines established by the International Union for the Protection of New Varieties of Plants (UPOV) for cultivar registration and the Organisation for Economic Co-operation and Development (OECD) for seed certification. Data were collected for terminal leaflet length, width and ratio, angle of stem growth, date of first flowering, stem height at first flowering, flower colour, cutting recovery height, and disease scores. None of these characters were sufficient to identify or discriminate among the six cultivars. The results indicate a need to find cost-effective and efficient laboratory techniques to enhance the assessment of distinctness of lucerne cultivars (UPOV) and for determining cultivar purity for lucerne seed certification (OECD).
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Epipolythiodioxopiperazine toxins are secreted by a range of fungi, including Leptosphaeria maculans, which produces sirodesmin, and Aspergillus fumigatus, which produces gliotoxin. The L. maculans biosynthetic gene cluster for sirodesmin includes an ABC transporter gene, sirA. Disruption of this gene led to increased secretion of sirodesmin into the medium and an altered ratio of sirodesmin to its immediate precursor. The transcription pattern of a peptide synthetase that catalyses an early step in sirodesmin biosynthesis was elevated in the sirA mutant by 47% over a 7-day period. This was consistent with the finding that the transporter mutant had elevated sirodesmin levels. Despite increased production of sirodesmin, the sit-A mutant was more sensitive to both sirodesmin and gliotoxin. The putative gliotoxin transporter gene, gliA, (a major facilitator superfamily transporter) from A.fumigatus complemented the tolerance of the L. maculans sirA mutant to gliotoxin, but not to sirodesmin. The results indicate that SirA contributes to self-protection against sirodesmin in L. maculans and suggest a transporter other than SirA is primarily responsible for efflux of endogenously produced sirodesmin. (C) 2004 Elsevier Inc. All rights reserved.
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The sulfonylureas and imidazolinones are potent commercial herbicide families. They are among the most popular choices for farmers worldwide, because they are nontoxic to animals and highly selective. These herbicides inhibit branched-chain amino acid biosynthesis in plants by targeting acetohydroxyacid synthase (AHAS, EC 2.2.1.6). This report describes the 3D structure of Arabidopsis thaliana AHAS in complex with five sulfonylureas (to 2.5 angstrom resolution) and with the imidazolinone, imazaquin (IQ; 2.8 angstrom). Neither class of molecule has a structure that mimics the substrates for the enzyme, but both inhibit by blocking a channel through which access to the active site is gained. The sulfonylureas approach within 5 angstrom of the catalytic center, which is the C2 atom of the cofactor thiamin diphosphate, whereas IQ is at least 7 angstrom from this atom. Ten of the amino acid residues that bind the sulfonylureas also bind IQ. Six additional residues interact only with the sulfonylureas, whereas there are two residues that bind IQ but not the sulfonylureas. Thus, the two classes of inhibitor occupy partially overlapping sites but adopt different modes of binding. The increasing emergence of resistant weeds due to the appearance of mutations that interfere with the inhibition of AHAS is now a worldwide problem. The structures described here provide a rational molecular basis for understanding these mutations, thus allowing more sophisticated AHAS inhibitors to be developed. There is no previously described structure for any plant protein in complex with a commercial herbicide.
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Allowing plant pathology students to tackle fictitious or real crop problems during the course of their formal training not only teaches them the diagnostic process, but also provides for a better understanding of disease etiology. Such a problem-solving approach can also engage, motivate, and enthuse students about plant pathologgy in general. This paper presents examples of three problem-based approaches to diagnostic training utilizing freely available software. The first provides an adventure-game simulation where Students are asked to provide a diagnosis and recommendation after exploring a hypothetical scenario or case. Guidance is given oil how to create these scenarios. The second approach involves students creating their own scenarios. The third uses a diagnostic template combined with reporting software to both guide and capture students' results and reflections during a real diagnostic assignment.