Tagged: plant defence







Drying out defenses: drought reduces tree defense system

Drought stress is becoming increasingly common with climate change, with negative impacts on tree growth and survival. The mechanisms of drought mortality in trees are often attributed to carbon starvation or hydraulic failure, however disease and herbivory could also cause mortality under drought. For this to happen, tree defense systems against pathogens and herbivores would have to be weakened under drought – but are they? Recently, in Tree Physiology, Sarah MacAllister and colleagues look at metabolic changes in Scots pine leaves during drought stress to determine whether plant defenses are weakened. They use an untargeted metabolomics approach – essentially measuring...

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Cornu aspersum

Snails use smell to select seedlings of favoured grassland species

Although Darwin recognised long ago the destructive impact that snails and slugs have on seedlings, we understand remarkably little about why these herbivores select different plants at their most vulnerable stage. Hanley et al. examine the role of volatile compounds in the attractiveness of seedlings of 14 grassland species to snails (Cornu aspersum, Helicidae). Selection is closely associated with different volatile profiles; specifically snails used characteristic odour cues (smell) to select preferred seedlings. The study shows how seedling selection occurs before snail attack, and explains why some plants avoid herbivory and establish even when molluscs are active and abundant.

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Wild radish seedlings growing outdoors in late autumn

Synthetic auxin resistance in wild radish is still an enigma

Guest author Danica Goggin finds wild radish is a problem weed in many agricultural regions. It is also very good at concealing its herbicide resistance strategies from inquisitive researchers. But with the introduction of synthetic auxin-resistant transgenic crops in North America, we need to keep chipping away at this plant’s shield of secrecy.

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Effect of pollination and herbivory treatments on the strength and direction of selection on several floral and inflorescence architecture traits in Lythrum salicaria

The role of herbivory in the selection of floral traits

Pollinators are often given precedence as the primary drivers behind the evolution of floral traits. Yet a growing body of research is beginning to stress the importance of other significant selective agents, particularly the role of herbivores that damage flower and fruit structures. By experimentally manipulating a population of Lythrum salicaria, Thomsen and Sargent demonstrate that leaf damage alone imposes selection on floral traits and constitutes an even stronger agent of change than selection by pollinators. Herbivores can have a greater impact on floral traits than pollinators, when such floral traits are relevant to a plant’s defense or compensation mechanisms.

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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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Maize bushy stunt phytoplasma (MBSP) induced diverse morphological changes in maize plants.

Sequence polymorphisms in a phytoplasma underlie organ proliferation in maize

Maize bushy stunt phytoplasma (MBSP) is a vector-borne pathogen that induces multiple morphological alterations in maize plants. Orlovskis et al. find that MBSP isolates from two maize growing regions of Southeast Brazil differ in strengths of disease symptom induction, including lateral branching. Whole genome sequencing of the MBSP isolates identified 86 polymorphic sites, of which 45% are located in protein-coding regions. Nine polymorphisms associate with lateral branching symptoms, one of which locates in a lipoprotein-encoding effector gene and two in a lipoprotein transporter. Surprisingly, other effector genes were conserved among the isolates, including an MBSP isolate from Mexico. This paper...

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