Tagged: hormones

Growing tomatoes

Relative fructose content and tomato susceptibility to Botrytis cinerea

Plant defence against Botrytis cinerea, a ubiquitous pathogenic fungus, is known to depend upon the mobilisation of sugars which provide energy and carbon skeletons for the production of antifungal compounds. Lecompte et al. hypothesise that glucose and fructose could play distinct roles in plant defence, showing that disease severity is highly correlated to the relative fructose content in tomato stem tissues, defined as the proportion of fructose in the plant soluble sugar pool. Conditions of higher susceptibility are associated with glucose accumulation in infected tissues. The physiological meaning of this distinct use of sugars for defence remains to be determined....

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Histological analysis of galls induced by Meloidogyne graminicola in resistant rice (Oryza glaberrima TOG5681) roots.

Rice resistance responses to the root-knot nematode Meloidogyne graminicola

Meloidogyne graminicola is responsible for production losses in rice (Oryza sativa) in Asia and Latin America. Petitot et al. assess the cytological and molecular mechanisms underlying nematode resistance identified in African rice (Oryza glaberrima). Rice resistance responses act at several steps along the nematode life-cycle to limit penetration and feeding site development, preventing efficient nematode reproduction. This study provides a novel set of candidate genes for O. glaberrima resistance to nematodes. This paper is part of the Annals of Botany Special Issue on Plant Immunity. It will be free access till June 2017 and after April 2018.

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Changing environments induce phenotype-specific responses. Phenotypic responses to changing environments range from plastic to robust. Environmental changes that occur predictably lead to programmed responses. Shown here is the transition between vegetative and reproductive growth induced by seasonal exposures to low and then high temperatures.

Molecular mechanisms of noise and robustness

Robustness, the inverse of noise, is a molecularly programmed feature of biological systems. The molecular networks of some organismal phenotypes like development are designed to maximize robustness, while other phenotypes like disease resistance have their pathways structured to allow for decreased robustness/increased noise to counteract evolution in the attacking organism. Lachowiec et al. describe the specific molecular components that are utilized in networks to finely tune the proper level of robustness/noise for an array of phenotypes.

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Chrysolaena obovata

Co-ordinated carbohydrate metabolism and hormone synthesis enables plants to survive unfavourable field conditions

Chrysolaena obovata, an aster of the Brazilian Cerrado, presents seasonal growth, marked by senescence of aerial organs in winter and subsequent regrowth at the end of this season. The underground reserve organs, the rhizophores, accumulate inulin-type fructans and confer tolerance to drought and low temperature. Fructans and fructan-metabolizing enzymes show a characteristic spatial and temporal distribution in the rhizophores during the developmental cycle. Previous studies have shown correlations between abscisic acid (ABA) or indole acetic acid (IAA), fructans, dormancy and tolerance to drought and cold, but the signalling mechanism for the beginning of dormancy and sprouting in this species is...

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Image: ‘Crabtree watching the Transit of Venus A.D. 1639’ by Ford Madox Brown; a mural at the Town Hall of Manchester, UK.

Transient VENUS

This year’s transit of Venus reminds me – albeit belatedly – to applaud the hard-working botanists of the Universities of Nottingham (UK), Ghent (Belgium), Leeds (UK) and Lyon (France) who have been exploring a more down-to-Earth – and ultimately more useful? – kind of Venus. Like all good phytologists they are interested in understanding the role of auxin in plant development. In order to get a better understanding of auxin biology it is important to identify where it actually works inside plant cells; a tall order, locating a tiny molecule in a small cell. Hitherto, a so-called DR5-based protocol was employed...

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A witch with broom, pumpkins and orange clothes

Botany for Halloween – Witches, Brooms and Pumpkins

At the moment, I am teaching plant hormones in our course on plant cell and developmental biology (BS1003). Fortunately, hormones and development link well with Halloween this year: we have witches, sitting on a broom, with a pumpkin, and for good measure some brightly colored leaves falling around them. Where is the connection? The broom is a good point to start : many species of trees have “witch’s brooms” on them, structures where a large number of small twigs arise from one region of a branch or the main trunk. The uncontrolled outgrowths are caused by other organisms which either...

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