Effector Avr4 in Phytophthora infestans Escapes Host Immunity Mainly Through Early Termination

Effector genes play critical roles in the antagonistic interactions between plants and pathogens. However, knowledge of mutation mechanisms and evolutionary processes in effector genes and the contribution of climatic factors to the evolution of effector genes are fragmented but important in sustainable management of plant diseases and securing food supply under changing climates. Here, we used a population genetic approach to explore the evolution of the Avr4 gene in Phytophthora infestans, the causal agent of potato blight. We found that the Avr4 gene exhibited a high genetic diversity generated by point mutation and sequence deletion. Frameshifts caused by a single base-pair deletion at the 194th nucleotide position generate two stop codons, truncating almost the entire C-terminal, which is important for effector function and R4 recognition in all sequences. The effector is under natural selection for adaptation supported by comparative analyses of population differentiation (FST) and isolation-by-distance between Avr4 sequences and simple sequence repeat marker loci. Furthermore, we found that local air temperature was positively associated with pairwise FST in the Avr4 sequences. These results suggest that the evolution of the effector gene is influenced by local air temperature, and the C-terminal truncation is one of the main mutation mechanisms in the P. infestans effector gene to circumvent the immune response of potato plants. The implication of these results to agricultural and natural sustainability in future climate conditions is discussed.

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Multiple Mechanisms Drive the Evolutionary Adaptation of Phytophthora infestans Effector Avr1 to Host Resistance

Journal of Fungi ◽

10.3390/jof7100789 ◽

2021 ◽

Vol 7 (10) ◽

pp. 789

Author(s):

Lin-Lin Shen ◽

Abdul Waheed ◽

Yan-Ping Wang ◽

Oswald Nkurikiyimfura ◽

Zong-Hua Wang ◽

...

Keyword(s):

Disease Management ◽

Phytophthora Infestans ◽

Host Resistance ◽

Population Genetic ◽

Base Substitution ◽

Intragenic Recombination ◽

Diversifying Selection ◽

Effector Gene ◽

Small Proteins ◽

Effector Genes

Effectors, a group of small proteins secreted by pathogens, play a central role in antagonistic interactions between plant hosts and pathogens. The evolution of effector genes threatens plant disease management and sustainable food production, but population genetic analyses to understand evolutionary mechanisms of effector genes are limited compared to molecular and functional studies. Here we investigated the evolution of the Avr1 effector gene from 111 Phytophthora infestans isolates collected from six areas covering three potato cropping regions in China using a population genetic approach. High genetic variation of the effector gene resulted from diverse mechanisms including base substitution, pre-termination, intragenic recombination and diversifying selection. Nearly 80% of the 111 sequences had a point mutation in the 512th nucleotide (T512G), which generated a pre-termination stop codon truncating 38 amino acids in the C-terminal, suggesting that the C-terminal may not be essential to ecological and biological functions of P. infestans. A significant correlation between the frequency of Avr1 sequences with the pre-termination and annual mean temperature in the collection sites suggests that thermal heterogeneity might be one of contributors to the diversifying selection, although biological and biochemical mechanisms of the likely thermal adaptation are not known currently. Our results highlight the risk of rapid adaptation of P. infestans and possibly other pathogens as well to host resistance, and the application of eco-evolutionary principles is necessary for sustainable disease management in agricultural ecosystems.

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Interval of days required for determining efficient relations between climatic factors and cotton flower and boll production

Canadian Journal of Plant Science ◽

10.4141/p01-013 ◽

2002 ◽

Vol 82 (3) ◽

pp. 499-506 ◽

Cited By ~ 1

Author(s):

Zakaria M Sawan ◽

Louis I Hanna ◽

Willis L McCuistion

Keyword(s):

Soil Temperature ◽

Air Temperature ◽

Surface Soil ◽

Cultural Practices ◽

Agricultural Research ◽

Climatic Factors ◽

Sunshine Duration ◽

Field Trials ◽

Cotton Production ◽

Surface Soil Temperature

The cotton plant (Gossypium spp.) is sensitive to numerous environmental factors. This study was aimed at predicting effects of climatic factors grouped into convenient intervals (in days) on cotton flower and boll production compared with daily observations. Two uniformity field trials using the cotton (G. barbadense L.) cv. Giza 75 were conducted in 1992 and 1993 at the Agricultural Research Center, Giza, Egypt. Randomly chosen plants were used to record daily numbers of flowers and bolls during the reproductive stage (60 days). During this period, daily air temperature, temperature magnitude, evaporation, surface soil temperature, sunshine duration, humidity, and wind speed were recorded. Data, grouped into intervals of 2, 3, 4, 5, 6, and 10 d, were correlated with cotton production variables using regression analysis. Evaporation was found to be the most important climatic variable affecting flower and boll production, followed by humidity and sunshine duration. The least important variables were surface soil temperature at 0600 and minimum air temperature. The 5-d interval was found to provide the best correlation with yield parameters. Applying appropriate cultural practices that minimize the deleterious effects of evaporation and humidity could lead to an important improvement in cotton yield in Egypt. Key words: Cotton, flower production, boll production, boll retention

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Dominant climatic factors driving annual runoff changes at the catchment scale across China

Hydrology and Earth System Sciences ◽

10.5194/hess-20-2573-2016 ◽

2016 ◽

Vol 20 (7) ◽

pp. 2573-2587 ◽

Cited By ~ 10

Author(s):

Zhongwei Huang ◽

Hanbo Yang ◽

Dawen Yang

Keyword(s):

Wind Speed ◽

Air Temperature ◽

Climate Changes ◽

Climatic Factors ◽

Southern China ◽

Resource Planning ◽

Annual Runoff ◽

Net Radiation ◽

Catchment Scale ◽

The Impact

Abstract. With global climate changes intensifying, the hydrological response to climate changes has attracted more attention. It is beneficial not only for hydrology and ecology but also for water resource planning and management to understand the impact of climate change on runoff. In addition, there are large spatial variations in climate type and geographic characteristics across China. To gain a better understanding of the spatial variation of the response of runoff to changes in climatic factors and to detect the dominant climatic factors driving changes in annual runoff, we chose the climate elasticity method proposed by Yang and Yang (2011). It is shown that, in most catchments of China, increasing air temperature and relative humidity have negative impacts on runoff, while declining net radiation and wind speed have positive impacts on runoff, which slow the overall decline in runoff. The dominant climatic factors driving annual runoff are precipitation in most parts of China, net radiation mainly in some catchments of southern China, air temperature and wind speed mainly in some catchments in northern China.

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Number of Candidate Effector Genes in Accessory Genomes Differentiates Pathogenic From Endophytic Fusarium oxysporum Strains

Frontiers in Plant Science ◽

10.3389/fpls.2021.761740 ◽

2021 ◽

Vol 12 ◽

Author(s):

Maria E. Constantin ◽

Like Fokkens ◽

Mara de Sain ◽

Frank L. W. Takken ◽

Martijn Rep

Keyword(s):

Fusarium Oxysporum ◽

Plant Species ◽

Genetic Basis ◽

Molecular Level ◽

Similar Amount ◽

Tomato Plants ◽

Grass Roots ◽

Effector Gene ◽

Effector Genes ◽

Potential Pathogen

The fungus Fusarium oxysporum (Fo) is widely known for causing wilt disease in over 100 different plant species. Endophytic interactions of Fo with plants are much more common, and strains pathogenic on one plant species can even be beneficial endophytes on another species. However, endophytic and beneficial interactions have been much less investigated at the molecular level, and the genetic basis that underlies endophytic versus pathogenic behavior is unknown. To investigate this, 44 Fo strains from non-cultivated Australian soils, grass roots from Spain, and tomato stems from United States were characterized genotypically by whole genome sequencing, and phenotypically by examining their ability to symptomlessly colonize tomato plants and to confer resistance against Fusarium Wilt. Comparison of the genomes of the validated endophytic Fo strains with those of 102 pathogenic strains revealed that both groups have similar genomes sizes, with similar amount of accessory DNA. However, although endophytic strains can harbor homologs of known effector genes, they have typically fewer effector gene candidates and associated non-autonomous transposons (mimps) than pathogenic strains. A pathogenic ‘lifestyle’ is associated with extended effector gene catalogs and a set of “host specific” effectors. No candidate effector genes unique to endophytic strains isolated from the same plant species were found, implying little or no host-specific adaptation. As plant-beneficial interactions were observed to be common for the tested Fo isolates, the propensity for endophytism and the ability to confer biocontrol appears to be a predominant feature of this organism. These findings allow prediction of the lifestyle of a Fo strain based on its genome sequence as a potential pathogen or as a harmless or even beneficial endophyte by determining its effectorome and mimp number.

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Identification of mimp-associated effector genes in Fusarium oxysporum f. sp. cubense race 1 and race 4 and virulence confirmation of a candidate effector gene

Microbiological Research ◽

10.1016/j.micres.2019.126375 ◽

2020 ◽

Vol 232 ◽

pp. 126375 ◽

Cited By ~ 1

Author(s):

Wenjun Chang ◽

Heng Li ◽

Hanqing Chen ◽

Fan Qiao ◽

Huicai Zeng

Keyword(s):

Fusarium Oxysporum ◽

Effector Gene ◽

Effector Genes ◽

Race 1 ◽

Race 4

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Sensitivity analysis of potential evapotranspiration to key climatic factors in the Shiyang River Basin

Journal of Water and Climate Change ◽

10.2166/wcc.2020.225 ◽

2020 ◽

Author(s):

Xuelei Zhang ◽

Weihua Xiao ◽

Yicheng Wang ◽

Yan Wang ◽

Miaoye Kang ◽

...

Keyword(s):

Sensitivity Analysis ◽

River Basin ◽

Air Temperature ◽

Climatic Factors ◽

Potential Evapotranspiration ◽

Mountainous Region ◽

Shiyang River Basin ◽

Increasing Trends ◽

Maximum Air Temperature ◽

Monteith Equation

Abstract This paper focuses on determining the spatial and temporal characteristics of the sensitivity coefficients (SCs) between potential evapotranspiration (ET0) and key climatic factors across the Shiyang River Basin (SYRB) from 1981 to 2015. Penman–Monteith equation and a sensitivity analysis were used to calculate ET0 and the SCs for key climatic factors. Sen's slope was used to analyze the observed series. According to the results, the sensitivity significances were in the order of relative humidity (RH) > net solar radiation (NSR) > wind speed (WS) > maximum air temperature (Tmax) > minimum air temperature (Tmin). The SCs for the RH and NSR were larger in the upper mountainous region, while the other three coefficients were larger in the middle and lower reaches. All five climatic factors for the ET0 SCs showed increasing trends in the mountainous region, and the Tmax, WS and RH SCs increased in the middle and lower reaches. Over the past 35 years, the change in ET0 was dominated by the air temperature (T), RH and NSR, and the increase in ET0 during the studied period was mainly due to the increases in T and NSR.

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Changes in Potential Evaporation in the Years 1952–2018 in North-Western Poland in Terms of the Impact of Climatic Changes on Hydrological and Hydrochemical Conditions

Water ◽

10.3390/w12030877 ◽

2020 ◽

Vol 12 (3) ◽

pp. 877 ◽

Cited By ~ 1

Author(s):

Monika Okoniewska ◽

Danuta Szumińska

Keyword(s):

Water Resources ◽

Air Temperature ◽

21St Century ◽

Climatic Factors ◽

Potential Evaporation ◽

Relative Air Humidity ◽

Chemical Conditions ◽

Physical And Chemical ◽

The Impact ◽

North Western

The paper analyses changes in potential evaporation E0 (mm) in north-western Poland in the years 1952–2018. E0 (mm) has been calculated according to Ivanov’s formula based on the monthly values of air temperature (t, °C) and relative air humidity (f, %) for six weather stations of the Institute of Meteorology and Water Management. The data were collected using the Statistica software ver. 13 and the QGIS software ver. 3.80. The results indicate statistically significant trends in the increase of E0 during the period 1952–2018, and that it is particularly high during the spring and summer months, which should be associated with a statistically significant increase in air temperature and a decrease in relative humidity at all examined stations. The results also indicate an exceptionally high increase in evaporation since the end of the 20th century and in the 21st century, which reflects a potentially higher risk of permanent changes in hydrological conditions. The research results point to the major role of climatic factors in the often-dramatic decreases in water resources observed in the 21st century, particularly in lakes and small watercourses. The progressing reduction of water resources may cause permanent changes in physical and chemical conditions in waterbodies.

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Temperature-Mediated Plasticity Regulates the Adaptation of Phytophthora infestans to Azoxystrobin Fungicide

Sustainability ◽

10.3390/su12031188 ◽

2020 ◽

Vol 12 (3) ◽

pp. 1188 ◽

Cited By ~ 3

Author(s):

Yahuza Lurwanu ◽

Yan-Ping Wang ◽

Waheed Abdul ◽

Jiasui Zhan ◽

Li-Na Yang

Keyword(s):

Phytophthora Infestans ◽

Population Differentiation ◽

Food Production ◽

Plant Pathogens ◽

Target Genes ◽

Common Garden ◽

Plant Diseases ◽

Control Effectiveness ◽

Plant Disease Management ◽

Simple Sequence

Fungicide is one of the main approaches used in agriculture to manage plant diseases for food production, but their effectiveness can be reduced due to the evolution of plant pathogens. Understanding the genetics and evolutionary processes responsible for the development of fungicide resistance is a key to food production and social sustainability. In this study, we used a common garden experiment to examine the source of genetic variation, natural selection, and temperature contributing to the development of azoxystrobin resistance in Phytophthora infestans and infer sustainable ways of plant disease management in future. We found that plasticity contributed to ~40% of phenotypic variation in azoxystrobin sensitivity while heritability accounted for 16%. Further analysis indicated that overall population differentiation in azoxystrobin sensitivity (QST) was significantly greater than the overall population differentiation in simple sequence repeat (SSR) marker (FST), and the P. infestans isolates demonstrated higher level of azoxystrobin sensitivity at the higher experimental temperature. These results suggest that changes in target gene expression, enzymatic activity, or metabolic rate of P. infestans play a more important role in the adaptation of the pathogen to azoxystrobin resistance than that of mutations in target genes. The development of azoxystrobin resistance in P. infestans is likely driven by diversifying selection for local adaptation, and elevated temperature associated with global warming in the future may increase the effectiveness of using azoxystrobin to manage P. infestans. The sustainable approaches for increasing disease control effectiveness and minimizing the erosion of the fungicide efficacy are proposed.

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Impacts of Climatic Change on Reference Crop Evapotranspiration across Different Climatic Zones of Ningxia at Multi-Time Scales from 1957 to 2018

Advances in Meteorology ◽

10.1155/2020/3156460 ◽

2020 ◽

Vol 2020 ◽

pp. 1-23

Author(s):

Ziyang Zhao ◽

Hongrui Wang ◽

Cheng Wang ◽

Wangcheng Li ◽

Hao Chen ◽

...

Keyword(s):

Water Management ◽

Time Scales ◽

Air Temperature ◽

Climatic Factors ◽

Crop Evapotranspiration ◽

Climatic Zones ◽

Reference Crop Evapotranspiration ◽

Short Period ◽

The Impact ◽

Reference Crop

The impact of global climate change on agroecosystems is growing, affecting reference crop evapotranspiration (ET0) and subsequent agricultural water management. In this study, the climate factors temporal trends, the spatiotemporal variation, and the climate driving factors of ET0 at different time scales were evaluated across the Northern Yellow River Irrigation Area (NYR), Central Arid Zone (CAZ), and Southern Mountain Area (SMA) of Ningxia based on 20 climatic stations’ daily data from 1957 to 2018. The results showed that the Tmean (daily mean air temperature), Tmax (daily maximum air temperature), and Tmin (daily minimum air temperature) all had increased significantly over the past 62 years, whilst RH (relative humidity), U2 (wind speed at 2 m height), and SD (sunshine duration) had significantly decreasing trends across all climatic zones. At monthly scale, the ET0 was mainly concentrated from April to September. And at annual and seasonal scales, the overall increasing trends were more pronounced in NX, NYR, and SMA, while CAZ was the opposite. For the spatial distribution, ET0 presented a trend of rising first and then falling at all time scales. The abrupt change point for climatic factors and ET0 series was obtained at approximately 1990 across all climatic zones, and the ET0 had a long period of 25a and a short period of 10a at annual scale, while it was 15a and 5a at seasonal scale. RH and Tmax were the most sensitive climatic factors at the annual and seasonal scales, while the largest contribution rates were Tmax and SD. This study not only is important for the understanding of ET0 changes but also provides the preliminary and elementary reference for agriculture water management in Ningxia.

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