Chloroplast movement and positioning protein CHUP1 is required for focal immunity against Phytophthora infestans

When a plant detects a pathogen, chloroplasts terminate photosynthetic activity and uptake vital roles in the immune system to help stave off infection, including the production of defense hormone precursors and antimicrobial reactive oxygen species. Additionally, chloroplasts associate with the nucleus and produce greater numbers of tubular extensions called stromules during immune challenge. We previously showed that during infection by the potato blight pathogen Phytophthora infestans, chloroplasts accumulate at the pathogen haustoria, hyphal extensions that are accommodated within the host cell. However, the extent to which chloroplast positioning around haustoria, or at the nucleus, contributes to immunity during infection remains unknown. Here we show a striking increase in the susceptibility to P. infestans of Nicotiana benthamiana CRISPR knock-out lines lacking the chloroplast movement and anchoring gene, CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1). However, the positioning of chloroplasts around the haustorium or nucleus is not impaired in the absence of CHUP1. Further, loss of CHUP1 leads to an extreme clustering of chloroplasts around the nucleus in the presence and absence of infection, showing that greater chloroplast-nucleus association does not necessarily equate to more robust immunity. While plants lacking CHUP1 have reduced basal stromules, they are still able to induce stromules following immune stimulation, indicating that multiple populations of stromules exist. Lastly, we found that CHUP1 is required for proper deposition of callose - a cell wall material implicated in pathogen penetration resistance - around P. infestans haustorium, but not for other core immune processes. Our results implicate chloroplasts in plant focal immunity and point to a key role of CHUP1 in facilitating the deposition of defense material at the pathogen interface.

Potato late blight disease prediction using meteorological parameters in Northern Himalayas of India

Weather parameters play an important role in the spread of potato late blight of caused by Phytophthora infestans (Mont.) de Bary has historically been serious disease of potatoes through worldwide, including India. Due to spatial variation in prevailing weather conditions, its severity varies from region to region. Disease development process and the weather parameters are well understood and have been utilized for disease developing forecasting models and decision support system. Therefore, an experiment was conducted for two consecutive cropping seasons (2017 & 2018) to develop a forecasting model against late blight of potato using stepwise regression analysis for Northern Himalayas in India. Maximum and minimum temperature, relative humidity, rainfall and wind speed appeared to be most significant factors in the potato late blight disease development. The meteorological conditions conducive for the development of potato late blight disease were characterized. Maximum and minimum temperatures in the range of 15.0 – 28.0°C and 2.0 – 12.0°C were found favorable for potato blight disease. Similarly, relative humidity, rainfall and wind speed in the range of 85 - 95 per cent, 15.5 - 20.75 mm and 1.0 - 5.5 Km h-1, respectively, were conducive for potato late blight disease which are helpful in disease development.

The Impact of Effective Microorganisms on Flesh Color and Chemical Composition of Raw Potato Tubers

The objective of this study was to develop an innovative method of potato cultivation, with limited use of chemicals, for use in food processing. The results of the research are based on field experiments carried out between 2015 and 2017 at the Experimental Station in Parczew, Poland. The first-order factors were cultivation practices: A—standard cultivation practices with fungicides to control potato blight; and cultivation practices B, C, and D using the application of effective microorganisms (EM). The potato varieties were the second-order factor. The scope of the research included assessing the flesh color of the raw tubers and the content of dry mass, sugars and vitamin C. The color measurement of raw tubers was carried out using the CIEL *a *b* system. Cultivation methods using applications of effective microorganisms contributed significantly to the change in color brightness of the raw tuber flesh compared to the standard methods. The flesh color of the research potato cultivar tubers, their trichromatic coordinates and the reactions of potato varieties were determined according to the cultivation practices used. It was found that the brightness of the color of raw tuber flesh depends on the content of dry matter and the content of reducing sugars in the tubers.

Plant Endophytic Fungus Extract ZNC Improved Potato Immunity, Yield, and Quality

Endophytic fungi play an important role in plant survival and reproduction, but the role of their metabolites in plant growth and immunity, as well as in crop quality formation, is poorly understood. Zhinengcong (ZNC) is a crude ethanol extract from the endophytic fungus Paecilomyces variotii, and previous studies have shown that it can improve the growth and immunity in Arabidopsis thaliana. The aim of the study was to reveal the trade-off balance between plant growth and immunity by evaluating the mechanisms of ZNC on potato growth, yield, and priming immunity against the oomycete Phytophthora infestans indoors and in the field. ZNC maintained a good balance between plant growth and resistance against P. infestans with high activity. It induced the reactive oxygen species (ROS) production, promoted plant growth, yield and quality parameters, enhanced the expression of indoleacetic acid (IAA) related genes, and increased the absorption of nitrogen from the soil. Moreover, the plant endophytic fungus extract ZNC stimulated the pathogen-associated molecular pattern (PAMP) triggered immunity (PTI) pathway and contributed to the ZNC-mediated defense response. Two years of field trials have shown that irrigation with ZNC at one of two optimal concentrations of 1 or 10ng/ml could significantly increase the output by 18.83% or more. The quality of potato tubers was also greatly improved, in which the contents of vitamin C, protein, and starch were significantly increased, especially the sugar content was increased by 125%. Spray application of ZNC onto potato plants significantly reduced the occurrence of potato blight disease with 66.49% of control efficacy at 200ng/ml and increased the potato yield by 66.68% or more in the field. In summary, plant endophytic fungus extract ZNC promoted potato immunity, yield, and quality and presented excellent potential in agricultural applications.

Implementing the modified potato blight risk forecasting model in the Republic of Ireland – the New Irish Rules

<p> </p><p>Potato late blight caused by oomycete <em>Phytophthora infestans</em> (Mont) De Bary, is arguably the most important disease of potato in terms of economic losses and environmental and economic impact of the disease management in Ireland and globally. The pathogen spreads rapidly in humid weather in the foliage of potatoes and tomatoes, causing the foliage to decay and the infection of the potato/tomato. Due to the pathogen’s dependence on weather conditions, a number of forecasting methods have been developed to reduce the input of pesticides and fungicides required to control the disease. Blight is of particular significance to Ireland, following the decimation of the potato crop in the 1850s which, among other colonial factors, contributed to widespread famine, emigration and death. Until recently, blight in Ireland has been forecast using the Irish Rules. The model was developed in the 1950s and calibrated based on the sparse meteorological station coverage at the time and lower risk perception by growers.</p><p> </p><p>Since then, the understanding of the pathogen’s development and its relationship to meteorological situation has advanced. This has led to the development of a modified open-source Irish Rules model written in R which facilitates improved forecasting and seasonal re-evaluation of the Irish Rules (Cucak et al., 2019). The new method reduces the threshold for relative humidity from 90% to 88% and the initial (sporulation) period from 12 hours to 10 hours, the analysis also showed thresholds for blight epidemics could be changed from 10°C to 12°C. Though risk estimation has increased compared to the previous rules, estimated chemical usage is still lower compared to standard grower’s practice. The new methodology is now referred to as the New Irish Rules.</p><p> </p><p>This research presents the implementation of this new blight forecasting model in Met Éireann’s operational infrastructure, ensuring methods for forecasting blight are as up-to-date as possible and are using industry-wide best-practice.</p><p>References: </p><p>Cucak, M., Sparks, A., Moral, R. D. A., Kildea, S., Lambkin, K., & Fealy, R. (2019). Evaluation of the ‘Irish rules’: the potato late blight forecasting model and its operational use in the Republic of Ireland. <em>Agronomy</em>, 9(9), 515.</p>

Enhanced Field-Based Detection of Potato Blight in Complex Backgrounds Using Deep Learning

Rapid and automated identification of blight disease in potato will help farmers to apply timely remedies to protect their produce. Manual detection of blight disease can be cumbersome and may require trained experts. To overcome these issues, we present an automated system using the Mask Region-based convolutional neural network (Mask R-CNN) architecture, with residual network as the backbone network for detecting blight disease patches on potato leaves in field conditions. The approach uses transfer learning, which can generate good results even with small datasets. The model was trained on a dataset of 1423 images of potato leaves obtained from fields in different geographical locations and at different times of the day. The images were manually annotated to create over 6200 labeled patches covering diseased and healthy portions of the leaf. The Mask R-CNN model was able to correctly differentiate between the diseased patch on the potato leaf and the similar-looking background soil patches, which can confound the outcome of binary classification. To improve the detection performance, the original RGB dataset was then converted to HSL, HSV, LAB, XYZ, and YCrCb color spaces. A separate model was created for each color space and tested on 417 field-based test images. This yielded 81.4% mean average precision on the LAB model and 56.9% mean average recall on the HSL model, slightly outperforming the original RGB color space model. Manual analysis of the detection performance indicates an overall precision of 98% on leaf images in a field environment containing complex backgrounds.

Was the Great Irish Famine a Colonial Famine?

This article reviews the historical debate on the colonial causation and dimensions of the Great Irish Famine of 1845-50. It does so by briefly reviewing the evolution of the colonial relationship between Great Britain and Ireland before focusing on a number of specific fields of debate relating to the coloniality of the Irish famine. These include the economic structures and dynamics developing over the century before 1845 and the vulnerability of Irish society, the vector of the potato blight and its impact on food availability, and, most extensively, the motivations for and characteristics of British state response to the catastrophe. The variant interpretations of these factors in the nationalist, revisionist, post-revisionist, and post-colonial historiography are reviewed. The author concludes by drawing on his own primary research to suggest that, while shaped by colonial stereotypes and a preoccupation with social engineering, the British state and public response to the Irish crisis was varied and not intentionally genocidal, although ultimately subordinating humanitarianism to perceived British national interest. Critical British contemporaries drew negative parallels between the neglect of Ireland and the prioritization of imperial expansion overseas, while Irish nationalists concluded that the mortality of the famine demonstrated the bankruptcy of the British-Irish Union of 1800.

Future climate risk to UK agriculture from heat and humidity changes

<p>Assessments of current and future climate risk are required for adaptation planning to increase resilience and enable society to cope with future climate hazards. Here we identify case studies of compound hazard (involving heat and humidity) events of interest to the UK agricultural sector and present a framework for comparing the frequency and duration of compound events now to those projected in 50 years’ time. We use high resolution (12 km) simulations from the UK Climate Projections to explore how the frequency and duration of instances of potato blight and thermal heat stress to dairy cattle may change locally under RCP 8.5 emissions forcing. We combine hazard (temperature and humidity data) with vulnerability (specific threshold exceedance) and exposure (regional dairy cattle numbers/potato growing area) to estimate risk. Regions where most potatoes are grown, and where the potato blight risk is greatest in both the current and future climate, include the East of England, Yorkshire and the Humber and Eastern Scotland. By 2070, potato blight occurrences may increase by 70 % in East Scotland and between 20 - 30 % across the East of England, the Midlands and Yorkshire and the Humber. Assuming dairy cattle spatial distributions remain the same, the area of greatest risk now and in the future is South West England, with notable increases in risk across Northern Ireland, Wales, the Midlands, North West England and North West Scotland. Dairy cattle heat stress (using a temperature-humidity index) is projected to increase by over 1000 % in South West England, the region with the most dairy cattle. Finally, we consider projected changes to UK seasons, using 2018 as a template, where a cold spring followed by a warm/dry summer resulted in hay/silage shortages. In addition to reduced crop yields in 2018, cattle were kept inside for longer in the cold spring and in the warm/dry summer, due to heat stress and poor grass quality. UK Climate Projections indicate that the annual probability of cold spring/warm summer conditions will decrease in future, but the annual probability of longer dry/warm summers will increase. We conclude that the agricultural sector should consider suitable climate adaptation measures to minimise the risk of dairy cattle thermal heat stress, increased potato blight, and longer dry/warm summer conditions.</p>

The Dependence of Crop Potatoes on the Level of Irrigation under Polish Conditions

The aim of the study was to evaluate the dependence of potato crops on the level of irrigation in three mesoregions of Poland. The field experiments were carried out in 2009–2011 according to an obligatory methodology for evaluation of crop cultivars. Three factors were tested: two cultivation practices (with irrigation and without irrigation as control), five potato cultivars, and three locations (Masłowice, Szczecin-Dąbie, and Węgrzce). The study was conducted in randomized blocks in triplicate. The study included the same nutrition across locations and protection against potato blight. Irrigation was applied according to the criterion of optimal soil moisture at a humidity decrease below 70% of the field water capacity. At the time of harvest, total and commercial yields of tubers were determined. Detailed analysis of the dependent variables, total and marketable yield, and the independent variables for the second harvest date, confirmed confidence in the achieved results. The coefficients of variation for total and marketable yield, on the second harvest date, were 23% and 25%, respectively, which means high stability for the results. Irrigation of potato plantations contributed to an increase in the total yield of tubers in the first harvest term by 3.22 t·ha−1 and by 7.23 t·ha−1 -in the second term; and the commercial yield of tubers by 3.45 t·ha−1 in the first term and by 7.42 t·ha−1 -in the second term of tuber harvest. The highest watering efficiency in the first harvest time, 60 days after planting, was distinguished by the “Miłek” variety, and in the second harvest date by the “Denar” variety.

Economic effectiveness of using fungicides in the protection of potato against Phytophthora infestans and Alternaria spp.

The aim of the research carried out in 2014–2016 at the Plant Breeding and Acclimatization Institute in Jadwisin was to assess the economic effectiveness of the use of fungicides in combating the causative agents of potato blight and alternaria on plants of four edible potato varieties with different resistance to Phytophthora infestans. The experiment included two objects: control – without chemical protection and protection – in which from 3 to 5 chemical treatments were performed. In the protected object obtained increase of yield of tubers was 20.4%. The value of saved production amounted to an average of 4.181.8 zł/ha. In the years of research in which meteorological conditions favored the development of late blight and alternaria, high profitability of using fungicides was found. Orientation index of profitability (E2) was in the range of 2.5–4.0, which means that the performed plant protection treatment constituted from 2.5 to 4.0% of the value of the obtained tuber yield per 1 hectare.