The zig-zag-zig in oomycete–plant interactions

In addition to a range of preformed barriers, plants defend themselves against microbial invasion by detecting conserved, secreted molecules, called pathogen-associated molecular patterns (PAMPs). PAMP-triggered immunity (PTI) is the first inducible layer of plant defence that microbial pathogens must navigate by the delivery of effector proteins that act to suppress or otherwise manipulate key components of resistance. Effectors may themselves be targeted by a further layer of defence, effector-triggered immunity (ETI), as their presence inside or outside host cells may be detected by resistance proteins. This 'zig-zag-zig' of tightly co-evolving molecular interactions determines the outcome of attempted infection. In this article, we consider the complex molecular interplay between plants and plant pathogenic oomycetes, drawing on recent literature to illustrate what is known about oomycete PAMPs and elicitors of defence responses, the effectors they utilize to suppress PTI, and the phenomenal molecular 'battle' between effector and resistance ( R ) genes that dictates the establishment or evasion of ETI.     

THE NEW MILITARY MEDICAL ETHICS: LEGACIES OF THE GULF WARS AND THE WAR ON TERROR

United States military medical ethics evolved during its involvement in two recent wars, Gulf War I (1990–1991) and the War on Terror (2001–). Norms of conduct for military clinicians with regard to the treatment of prisoners of war and the administration of non‐therapeutic bioactive agents to soldiers were set aside because of the sense of being in a ‘new kind of war’. Concurrently, the use of radioactive metal in weaponry and the ability to measure the health consequences of trade embargos on vulnerable civilians occasioned new concerns about the health effects of war on soldiers, their offspring, and civilians living on battlefields. Civilian medical societies and medical ethicists fitfully engaged the evolving nature of the medical ethics issues and policy changes during these wars. Medical codes of professionalism have not been substantively updated and procedures for accountability for new kinds of abuses of medical ethics are not established. Looking to the future, medicine and medical ethics have not articulated a vision for an ongoing military‐civilian dialogue to ensure that standards of medical ethics do not evolve simply in accord with military exigency.     

Male copulation frequency and female competition for fertilizations in a promiscuous brood parasite, the Pin-tailed Whydah Vidua macroura

Male Pin-tailed Whydahs Vidua macroura copulate infrequently and terminate most courtship displays, even when females are highly receptive. Female sexual interference is aimed at preventing other females from copulating, and is nearly always successful.     

Integrative taxonomy improves understanding of native beneficial fauna: revision of the Nearctic Peristenus pallipes complex (Hymenoptera: Braconidae) and implications for release of exotic biocontrol agents

The Nearctic Peristenus pallipes complex (Hymenoptera: Braconidae) consists of two species groups that are further divided into nine species, separated largely using ecological rather than morphological differences. The species are re‐examined with an integrative approach using morphometric multivariate ratios, molecular (COI and CytB), and ecological data to test the validity of the nine species. The data support only three valid species [P. dayi Goulet, P. mellipes (Cresson) and P. howardi Shaw] rather than nine. New synonymies include: P. braunae Goulet under P. dayi Goulet 2006 syn.n. ; P. carcamoi Goulet, P. otaniae Goulet and P. pseudopallipes (Loan) under P. mellipes (Cresson) syn.n. , and finally P. broadbenti Goulet 2006 and P. gillespiei Goulet 2006 under P. howardi Shaw 1999 syn.n . In light of these taxonomic revisions, the biology and distributions of the Nearctic P. pallipes complex are updated, resulting in three morphologically variable, widespread, multivoltine species rather than nine largely univoltine species with patchy distributions. The integrative taxonomic approach used here allowed for a more accurate delineation of native fauna and their potential to be competitively displaced by foreign biocontrol agents.     

Aphid saliva

Within the Aphidoidea, most species of Aphididae, as long as they are in small numbers and not carrying plant viruses, do little perceptible damage to their food plants. In species that cause toxicoses, it is usually assumed that some component of the saliva must be responsible. Paradoxically, however, the salivary enzymes of Aphididae are similar to those that already occur in plants – oxidases and enzymes that depolymerize polysaccharides – and the salivary enzymes are injected in very small amounts relative to their counterparts in the plant. Damage to plants triggers defensive, biochemical responses, and it is suggested that the injected enzymes serve mainly to divert or counter responses at the immediate interface of stylets and plant tissues. The saliva of Aphididae contains non-enzymic, reducing compounds which, in the presence of oxidases, can combine with and inactivate defensive phytochemicals – including those released in response to damage and transported in the phloem sieve tube sap on which Aphididae feed. Salivary and gut oxidases deactivate ingested phytochemicals by oxidative polymerization. Aphididae inject saliva into sieve tubes before sustained ingestion of sap, and this saliva has been presumed to condition the sieve tubes, but in what way remains unclear. It is suggested that there is a dynamic biochemical interaction between aphids and plants; that the interaction is usually well balanced for most of the Aphididae; hence, no outcome is readily observable. Where a significant imbalance occurs, however, either the aphid is unable to feed, i.e. the plant is resistant, and/or the aphid does not effectively counter a hypersensitive response. Not all plant responses are disadvantageous to aphids. Gall-forming Aphidoidea trigger and control abnormal growth in the plant to the insects' advantage, possibly by eliciting vigorous oxidation in selective meristematic tissues, thereby limiting supply of molecular oxygen and inhibiting oxygen-dependent growth-controls. Current problems and possible approaches for further research are reviewed.     

FACTORS AFFECTING THE BEHAVIOUR AND ACTIVITY OF THE CABBAGE ROOT FLY (ERIOISCHIA BRASSICAE BCHÉ)

The behaviour of cabbage root flies is governed by their need for food and shelter. Captive flies fed on sugar solution lived for periods up to 62 days, and a bred female laid 122 eggs.
Weather conditions determine the activity and the length of life of the flies. Feeding and egg-laying occur in warm sunny weather, and long periods of sunshine with temperatures of at least 60° F. in the latter half of April are associated with the onset of attack on the host plants. In cold or wet weather the flies shelter in soil or in thick herbage, and if they are immobilized for some time they die of starvation. In this way, the onset of cold weather checks the development of cabbage root fly attack. Details are given to show how the weather affected the activity of the flies in the springs of 1948–50 inclusive.
Eggs are laid in batches of varying size at irregular intervals during approximately 4 weeks. The position of the eggs about the host plants is affected by weather conditions. They are usually laid in the soil, but when the pressure of sunshine and drought is removed they are laid freely on aerial parts of the plants.
Knowledge of the influence of the weather on the activity of the flies enables attack to be anticipated with some degree of accuracy and control measures to be carefully timed.     

Narrow-leafed Lupins with Restricted Branching

Crop phenology is one of the most important characters influencingproductivity in a given environment. Narrow-leafed lupin (Lupinusangustifolius L.) is a major grain legume crop in southern Australiawith general phenological adaptation to this Mediterranean-typeenvironment. However, it is an indeterminate crop with severalassociated limitations to productivity, such as overlappingvegetative and reproductive growth, late grain filling and sometimesexcessive vegetative growth. Here we studied two novel typesof narrow-leafed lupin with restricted branching, which mightbe useful for overcoming these problems. These restricted branchinglupins arose spontaneously within a breeding population, inthe case of ‘Tallerack’, and within a farmer's cropin the case of ‘ Hurst’ and we compared them withthe ‘Merrit’, which is widely grown and has thenormal indeterminate branching habit. The morphology and developmentof the main shoot of these genotypes were similar. However,‘Hurst’ had much larger leaves. There were alsostriking differences in the lateral branches of the restrictedbranching types; they had fewer leaves than ‘Merrit’and flowered earlier. These differences were most marked in‘ Hurst’, where the upper main stem branches werereduced to a single floret in the axil of main stem leaves,and these flowers often exhibited abnormal morphology. Copyright2000 Annals of Botany Company Lupinus angustifolius L., narrow-leafed lupin, adaptation, development, morphology, branching, leaves, mutant, plastochron, phyllochron, floral initiation, flowering.