Richard N. Strange

Bio: Richard N. Strange is an academic researcher from University College London. The author has contributed to research in topics: Plant disease & Phytoalexin. The author has an hindex of 19, co-authored 36 publications receiving 2045 citations. Previous affiliations of Richard N. Strange include Birkbeck, University of London.

Plant Disease: A Threat to Global Food Security

Abstract: A vast number of plant pathogens from viroids of a few hundred nucleotides to higher plants cause diseases in our crops. Their effects range from mild symptoms to catastrophes in which large areas planted to food crops are destroyed. Catastrophic plant disease exacerbates the current deficit of food supply in which at least 800 million people are inadequately fed. Plant pathogens are difficult to control because their populations are variable in time, space, and genotype. Most insidiously, they evolve, often overcoming the resistance that may have been the hard-won achievement of the plant breeder. In order to combat the losses they cause, it is necessary to define the problem and seek remedies. At the biological level, the requirements are for the speedy and accurate identification of the causal organism, accurate estimates of the severity of disease and its effect on yield, and identification of its virulence mechanisms. Disease may then be minimized by the reduction of the pathogen's inoculum, inhibition of its virulence mechanisms, and promotion of genetic diversity in the crop. Conventional plant breeding for resistance has an important role to play that can now be facilitated by marker-assisted selection. There is also a role for transgenic modification with genes that confer resistance. At the political level, there is a need to acknowledge that plant diseases threaten our food supplies and to devote adequate resources to their control.

A new QTL for Ascochyta blight resistance in an RIL population derived from an interspecific cross in chickpea

Abstract: A linkage map in a population of recombinant inbred lines (RILs) derived from an interspecific cross between Cicer arietinum (ILC72) × Cicer reticulatum (Cr5-10), resistant and susceptible to blight, caused by Ascochyta rabiei, respectively, was obtained using RAPD, ISSR, STMS, isozyme (Pdf6) and flower colour (pink/white) markers. The map comprised ten linkage groups and covered a distance of 601.2 cM. When the population was evaluated for reaction to Ascochyta blight under field conditions by determining the Area Under the Disease Progress Curve (AUDPC), the distribution of frequencies was bimodal: most of the lines had an intermediate reaction, fewer were nearly as susceptible as the susceptible parent and none had values close to the resistant parent. A QTL explaining 28% of the variation in resistance was located in linkage group 2 (LG2). Five RAPD markers on this linkage group showed significant association with resistance (OPX04372, UBC881621, OPAI09746, OPAI09352 and OPAC12700) and the major QTL peak lay midway between OPAI09746 and UBC881621 which are 14.1 cM apart. Contrary to other studies, no association of linkage group 4 with resistance was found. The QTL for resistance to Ascochyta blight in this study is therefore different from QTLs for this character reported in other interspecific crosses and may be the same as that reported in linkage group 2 in intraspecific crosses where genes for resistance to races of Fusarium oxysporum f. sp. ciceri, causing wilt, are also located.

The oxidative burst in plant disease resistance

Abstract: Rapid generation of superoxide and accumulation of H2O2 is a characteristic early feature of the hypersensitive response following perception of pathogen avirulence signals. Emerging data indicate that the oxidative burst reflects activation of a membrane-bound NADPH oxidase closely resembling that operating in activated neutrophils. The oxidants are not only direct protective agents, but H2O2 also functions as a substrate for oxidative cross-linking in the cell wall, as a threshold trigger for hypersensitive cell death, and as a diffusible signal for induction of cellular protectant genes in surrounding cells. Activation of the oxidative burst is a central component of a highly amplified and integrated signal system, also involving salicylic acid and perturbations of cytosolic Ca2+, which underlies the expression of disease-resistance mechanisms.

Using Deep Learning for Image-Based Plant Disease Detection

Abstract: Crop diseases are a major threat to food security, but their rapid identification remains difficult in many parts of the world due to the lack of the necessary infrastructure. The combination of increasing global smartphone penetration and recent advances in computer vision made possible by deep learning has paved the way for smartphone-assisted disease diagnosis. Using a public dataset of 54,306 images of diseased and healthy plant leaves collected under controlled conditions, we train a deep convolutional neural network to identify 14 crop species and 26 diseases (or absence thereof). The trained model achieves an accuracy of 99.35% on a held-out test set, demonstrating the feasibility of this approach. Overall, the approach of training deep learning models on increasingly large and publicly available image datasets presents a clear path toward smartphone-assisted crop disease diagnosis on a massive global scale.

Fusarium ear blight (scab) in small grain cereals—a review

Abstract: This review of Fusarium ear blight (scab) of small grain cereals has shown that up to 17 causal organisms have been associated with the disease, which occurs in most cereal-growing areas of the world. The most common species were Fusarium graminearum (Gibberella zeae), F. culmorum, F, avenaceum (G, avenacea), F, poae and Microdochium nivale (Monographella nivalis). The disease was recorded most frequently under hot, wet climatic conditions where significant yield losses and mycotoxin accumulation in grain were reported. Possible sources of inoculum were reported as crop debris, alternative hosts and Fusarium seedling blight and foot rot of cereals. The mode of dispiersal of inoculum to ears remains unclear, but contaminated arthropod vectors, systemic fungal growth through plants, and wind and rain-splash dispersal of spores have been proposed. Infection of wheat ears was shown to occur mainly during anthesis, and it has been demonstrated that fungal growth stimulants may be present in anthers. Despite the importance of the disease, particularly during epidemic years, control methods are limited. Much effort has gone into breeding resistant wheat varieties and into improving our understanding of the possible mechanisms and genetic basis of resistance, with only moderate success. There are also surprisingly few reports of successful fungicidal or biological control of the disease in the field.