Role of Overwintering Forms of Erysiphe necator in Epidemiology of Grapevine Powdery Mildew in Palestinian Vineyards

2014 ◽  
Vol 2 (1) ◽  
pp. 20-25
Author(s):  
Ruba Abuamsha ◽  
Hajaj Hajjeh ◽  
Mazen Salman

The overwintering modes of E. necator were studied on Palestinian vineyards, through observations on the differentiation and maturation of cleistothecia and on the occurrence of flag-shoots (deriving from overwintering mycelium) in vineyards. Field surveys were carried out in 17 vineyards for the presence of Flag shoots and cleistothecia, both forms were not observed. Genetic structure and composition of E. necator populations were investigated by application of already available SCAR (Sequence Characterized Amplified Region) primers specific for the "flag-shoot" and "ascospore" biotypes. These primers were used to evaluate the dynamics of the spatial and temporal distribution of the two biotypes, into fungal populations present in 8 vineyards, with different cultivars and spray histories, in various Palestinian districts (Hebron, Bethlehem, Jerusalem, Ramallah, Jericho, Nablus, Jenin, Tulkarm). 397 samples were analyzed by the uses of the primer pairs UnE-UnF in PCR reactions. All samples were found to be of the ascospore biotypes. This finding shows that the “flag shoot” biotype, appears soon after bud breaking and disappears later, while the “ascospore” biotype is more frequently associated to later infections and bunches damages. Such information would be helpful to understand the reasons underlying possible temporal evolution of the pathogen's populations in vineyards, and can have important implications for powdery mildew rationale control strategies.

Author(s):  
Ruba Abuamsha ◽  
Hajaj Hajjeh ◽  
Mazen Salman

The overwintering modes of E. necator were studied on Palestinian vineyards, through observations on the differentiation and maturation of cleistothecia and on the occurrence of flag-shoots (deriving from overwintering mycelium) in vineyards. Field surveys were carried out in 17 vineyards for the presence of Flag shoots and cleistothecia, both forms were not observed. Genetic structure and composition of E. necator populations were investigated by application of already available SCAR (Sequence Characterized Amplified Region) primers specific for the "flag-shoot" and "ascospore" biotypes. These primers were used to evaluate the dynamics of the spatial and temporal distribution of the two biotypes, into fungal populations present in 8 vineyards, with different cultivars and spray histories, in various Palestinian districts (Hebron, Bethlehem, Jerusalem, Ramallah, Jericho, Nablus, Jenin, Tulkarm). 397 samples were analyzed by the uses of the primer pairs UnE-UnF in PCR reactions. All samples were found to be of the ascospore biotypes. This finding shows that the “flag shoot” biotype, appears soon after bud breaking and disappears later, while the “ascospore” biotype is more frequently associated to later infections and bunches damages. Such information would be helpful to understand the reasons underlying possible temporal evolution of the pathogen's populations in vineyards, and can have important implications for powdery mildew rationale control strategies.


Agronomy ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Antonio J. Mendoza-Fernández ◽  
Araceli Peña-Fernández ◽  
Luis Molina ◽  
Pedro A. Aguilera

Campo de Dalías, located in southeastern Spain, is the greatest European exponent of greenhouse agriculture. The development of this type of agriculture has led to an exponential economic development of one of the poorest areas of Spain, in a short period of time. Simultaneously, it has brought about a serious alteration of natural resources. This article will study the temporal evolution of changes in land use, and the exploitation of groundwater. Likewise, this study will delve into the technological development in greenhouses (irrigation techniques, new water resources, greenhouse structures or improvement in cultivation techniques) seeking a sustainable intensification of agriculture under plastic. This sustainable intensification also implies the conservation of existing natural areas.


2021 ◽  
Vol 22 (11) ◽  
pp. 5713
Author(s):  
Yiping Zhang ◽  
Li Zhang ◽  
Hai Ma ◽  
Yichu Zhang ◽  
Xiuming Zhang ◽  
...  

APETALA2/ETHYLENE RESPONSIVE FACTOR (AP2/ERF) transcription factors play important roles in plant development and stress response. Although AP2/ERF genes have been extensively investigated in model plants such as Arabidopsis thaliana, little is known about their role in biotic stress response in perennial fruit tree crops such as apple (Malus × domestica). Here, we investigated the role of MdERF100 in powdery mildew resistance in apple. MdERF100 localized to the nucleus but showed no transcriptional activation activity. The heterologous expression of MdERF100 in Arabidopsis not only enhanced powdery mildew resistance but also increased reactive oxygen species (ROS) accumulation and cell death. Furthermore, MdERF100-overexpressing Arabidopsis plants exhibited differential expressions of genes involved in jasmonic acid (JA) and salicylic acid (SA) signaling when infected with the powdery mildew pathogen. Additionally, yeast two-hybrid and bimolecular fluorescence complementation assays confirmed that MdERF100 physically interacts with the basic helix–loop–helix (bHLH) protein MdbHLH92. These results suggest that MdERF100 mediates powdery mildew resistance by regulating the JA and SA signaling pathways, and MdbHLH92 is involved in plant defense against powdery mildew. Overall, this study enhances our understanding of the role of MdERF genes in disease resistance, and provides novel insights into the molecular mechanisms of powdery mildew resistance in apple.


Author(s):  
Sergio F. A. Batista ◽  
Deepak Ingole ◽  
Ludovic Leclercq ◽  
Monica Menendez

Microbiology ◽  
2014 ◽  
Vol 160 (9) ◽  
pp. 1821-1831 ◽  
Author(s):  
Viveshree S. Govender ◽  
Saiyur Ramsugit ◽  
Manormoney Pillay

Adhesion to host cells is a precursor to host colonization and evasion of the host immune response. Conversely, it triggers the induction of the immune response, a process vital to the host’s defence against infection. Adhesins are microbial cell surface molecules or structures that mediate the attachment of the microbe to host cells and thus the host–pathogen interaction. They also play a crucial role in bacterial aggregation and biofilm formation. In this review, we discuss the role of adhesins in the pathogenesis of the aetiological agent of tuberculosis, Mycobacterium tuberculosis. We also provide insight into the structure and characteristics of some of the characterized and putative M. tuberculosis adhesins. Finally, we examine the potential of adhesins as targets for the development of tuberculosis control strategies.


Author(s):  
J. N. Kapoor

Abstract A description is provided for Podosphaera leucotricha. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Malus spp., chiefly on M. pumila (apple), peach (Prunus persica), quince (Cydonia ualgaris) and Photinia spp. also attacked (Hirata, 1966). Also reported on almond fruit (43, 2544). DISEASE: Powdery mildew of apple. GEOGRAPHICAL DISTRIBUTION: Africa (? Kenya, Rhodaia, South Africa, Tanzania); Asia (China, India, Israel, Japan, U.S.S.R.); Australia and New Zealand, Europe (widely distributed) North America (Canada and U.S.A.); South America (Argentina, Brazil, Chile, Colombia, Peru). (CMI map 118). TRANSMISSION: Overwinters on host as dormant mycdium in blossom buds. The role of deistothecia in overwintering is doubtful. Spread by wind-borne conidia (Anderson, 1956).


Archaea ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Elisabeth W. Vissers ◽  
Flavio S. Anselmetti ◽  
Paul L. E. Bodelier ◽  
Gerard Muyzer ◽  
Christa Schleper ◽  
...  

Despite their crucial role in the nitrogen cycle, freshwater ecosystems are relatively rarely studied for active ammonia oxidizers (AO). This study of Lake Lucerne determined the abundance of bothamoAgenes and gene transcripts of ammonia-oxidizing archaea (AOA) and bacteria (AOB) over a period of 16 months, shedding more light on the role of both AO in a deep, alpine lake environment. At the surface, at 42 m water depth, and in the water layer immediately above the sediment, AOA generally outnumbered AOB. However, in the surface water during summer stratification, when both AO were low in abundance, AOB were more numerous than AOA. Temporal distribution patterns of AOA and AOB were comparable. Higher abundances ofamoAgene transcripts were observed at the onset and end of summer stratification. In summer, archaealamoAgenes and transcripts correlated negatively with temperature and conductivity. Concentrations of ammonium and oxygen did not vary enough to explain theamoAgene and transcript dynamics. The observed herbivorous zooplankton may have caused a hidden flux of mineralized ammonium and a change in abundance of genes and transcripts. At the surface, AO might have been repressed during summer stratification due to nutrient limitation caused by active phytoplankton.


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