Plant Defence Research Papers - Academia.edu (original) (raw)

Background: The performance of five improved cowpea varieties under strip intercropping has been conducted in specific locations to assess their yield but their adaptability has not been determined. This paper presents results that... more

Background: The performance of five improved cowpea varieties under strip intercropping has been conducted in specific
locations to assess their yield but their adaptability has not been determined. This paper presents results that assessed the
adaptability of the improved cowpea varieties under strip intercropping in three locations in Limpopo province.
Methods: Five cowpea varieties (TVu 13464, IT86D-1010, Glenda, IT82E-16 and IT87K-499-35) and maize were planted under
strip intercropping in three locations (UL-Farm, Bela-Bela and Ga-Thaba) and two seasons. Data were collected on maturity, grain
yield, land equivalent ratio, pods plant-1, plant height and seed size and were analysed using Genstat 20.1.
Result: The ranking plot of grain yield indicates that the principal components (PC1 and PC2) explained 96.33% of the total sum of
square variation. The results indicate that IT86D-1010 and IT82E-16 matured early and were best yielders. The LER from IT82E-16,
IT86D-1010, TVu 13464 and IT87K-499-35 exceedingly performed better that from Glenda (Control) thus indicating that they are
superior in adaptation and in resource utilization. The performance and adaptation of the varieties varied across locations: IT82E-
16 is adapted to UL-Farm and Bela-Bela while IT86D-1010 and IT87K-499-35 are adapted to Ga-Thaba and their production should
be based on their best location(s)

Aims This study evaluated how different nitrogen forms affect growth and photosynthetic responses of cassava to CO 2 concentration. Methods Cassava was grown in 14-L pots in a greenhouse at 390 or 750 ppm of CO 2. Three nitrogen... more

Aims This study evaluated how different nitrogen forms affect growth and photosynthetic responses of cassava to CO 2 concentration. Methods Cassava was grown in 14-L pots in a greenhouse at 390 or 750 ppm of CO 2. Three nitrogen treatments were applied: (a) 12mM NO 3

Grapevine fanleaf virus (GFLV) (genus Nepovirus, family Secoviridae) causes fanleaf degeneration, one of the most damaging viral diseases of grapevines. Despite substantial advances at deciphering GFLV-host interactions, how this virus... more

Grapevine fanleaf virus (GFLV) (genus Nepovirus, family Secoviridae) causes fanleaf degeneration, one of the most damaging viral diseases of grapevines. Despite substantial advances at deciphering GFLV-host interactions, how this virus overcomes the host antiviral pathways of RNA silencing is poorly understood. In this study, we identified viral suppressors of RNA silencing (VSRs) encoded by GFLV, using fluorescence assays, and tested their capacity at modifying host gene expression in transgenic Nicotiana benthamiana expressing the enhanced green fluorescent protein gene (EGFP). Results revealed that GFLV RNA1-encoded protein 1A, for which a function had yet to be assigned, and protein 1B Hel , a putative helicase, reverse systemic RNA silencing either individually or as a fused form (1AB Hel) predicted as an intermediary product of RNA1 polyprotein proteolytic processing. The GFLV VSRs differentially altered the expression of plant host genes involved in RNA silencing, as shown by reverse transcription-quantitative PCR. In a co-infiltration assay with an EGFP hairpin construct, protein 1A upregulated NbDCL2, NbDCL4, and NbRDR6, and proteins 1B Hel and 1A+1B Hel upregulated NbDCL2, NbDCL4,

For hundreds of millions of years, large vertebrates (megafauna) have inhabited most of the ecosystems on our planet. During the late Quaternary, notably during the Late Pleistocene and the early Holocene, Earth experienced a rapid... more

For hundreds of millions of years, large vertebrates (megafauna) have inhabited most of the ecosystems on our planet. During the late Quaternary, notably during the Late Pleistocene and the early Holocene, Earth experienced a rapid extinction of large, terrestrial vertebrates. While much attention has been paid to understanding the causes of this massive megafauna extinction, less attention has been given to understanding the impacts of loss of megafauna on other organisms with whom they interacted. In this review, we discuss how the loss of megafauna disrupted and reshaped ecological interactions, and explore the ecological consequences of the ongoing decline of large vertebrates. Numerous late Quaternary extinct species of predators, parasites, commensals and mutualistic partners were associated with megafauna and were probably lost due to their strict dependence upon them (co-extinctions). Moreover, many extant species have megafauna-adapted traits that provided evolutionary bene...

Plant non‐specific lipid transfer proteins (LTPs) are proteins which transfer lipids between membranes in vitro and are believed to be involved in the transport of cutin monomers to the cuticle layer in vivo or in the plant defence... more

Plant non‐specific lipid transfer proteins (LTPs) are proteins which transfer lipids between membranes in vitro and are believed to be involved in the transport of cutin monomers to the cuticle layer in vivo or in the plant defence against phytopathogens. The complexation of DMPG, a diacyl phospholipid, by wheat ns‐LTP, a protein extracted from wheat seeds, was followed by 1H NMR and fluorescence spectroscopy. The global fold of the protein was calculated using the DIANA software package from a list of 968 distance constraints. The internal cavity volume, a feature common to all known ns‐LTP structures, was estimated to be 750 Å3 using the ‘CAVITE’ program. This model of the complex was obtained by inserting a lipid molecule in the cavity and was energy minimized. The study showed that the protein fold described for the free form was only weakly affected by the insertion of the bulky lipid. Observation of some intermolecular NOEs between the protein and the lipid glycerol moiety rev...

Dehydration proteins (dehydrins, DHNs) confer tolerance to water-stress deficit in plants. We performed a comparative genomics and evolutionary study of DHN genes in four model Brachypodium grass species. Due to limited knowledge on... more

Dehydration proteins (dehydrins, DHNs) confer tolerance to water-stress deficit in plants. We performed a comparative genomics and evolutionary study of DHN genes in four model Brachypodium grass species. Due to limited knowledge on dehydrin expression under water deprivation stress in Brachypodium, we also performed a drought-induced gene expression analysis in 32 ecotypes of the genus’ flagship species B. distachyon showing different hydric requirements. Genomic sequence analysis detected 10 types of dehydrin genes (Bdhn) across the Brachypodium species. Domain and conserved motif contents of peptides encoded by Bdhn genes revealed eight protein architectures. Bdhn genes were spread across several chromosomes. Selection analysis indicated that all the Bdhn genes were constrained by purifying selection. Three upstream cis-regulatory motifs (BES1, MYB124, ZAT) were detected in several Bdhn genes. Gene expression analysis demonstrated that only four Bdhn1-Bdhn2, Bdhn3, and Bdhn7 gene...

Grapevines from six Chilean regions were surveyed for virus diseases and tested for the presence of the most important viruses. ELISA testing of 2535 samples and confirmatory RT-PCR of some ELISA-negative samples from symptomatic and... more

Grapevines from six Chilean regions were surveyed for virus diseases and tested for the presence of the most important viruses. ELISA testing of 2535 samples and confirmatory RT-PCR of some ELISA-negative samples from symptomatic and symptomless vines gave the following infection rates: 6.36% for Grapevine fanleaf virus (GFLV); 4.67% for Grapevine leafroll associated virus 1 (GLRaV-1); 16.05% for Grapevine leafroll associated virus 2 (GLRaV-2); 6.41 % for Grapevine leafroll associated virus 3 (GLRaV-3); 0.26% for Grapevine leafroll associated virus 7 (GLRaV-7); 14.99% for Grapevine fleck virus (GFkV); 5.57% for Grapevine virus A (GVA) and 0.78% for Grapevine virus B (GVB). Strawberry latent ringspot virus (SLRSV) Tomato ringspot virus (ToRSV) and Arabis mosaic virus (ArMV) were not detected. Overall infection in the surveyed Chilean grapevines, considering ELISA and RT-PCR, was 32.35%. Virus infection ratio obtained from ELISA analysis in the six regions, varied between 21.19% (Regi...

Because of their sessile nature, plants evolved integrated defense and acclimation mechanisms to simultaneously cope with adverse biotic and abiotic conditions. Among these are systemic acquired resistance (SAR) and systemic acquired... more

Because of their sessile nature, plants evolved integrated defense and acclimation mechanisms to simultaneously cope with adverse biotic and abiotic conditions. Among these are systemic acquired resistance (SAR) and systemic acquired acclimation (SAA). Growing evidence suggests that SAR and SAA activate similar cellular mechanisms and employ common signaling pathways for the induction of acclimatory and defense responses. It is therefore possible to consider these processes together, rather than separately, as a common systemic acquired acclimation and resistance (SAAR) mechanism. Arabidopsis thaliana flavin-dependent monooxygenase 1 (FMO1) was previously described as a regulator of plant resistance in response to pathogens as an important component of SAR. In the current study, we investigated its role in SAA, induced by a partial exposure of Arabidopsis rosette to local excess light stress. We demonstrate here that FMO1 expression is induced in leaves directly exposed to excess li...

Potato Late Blight is the main pathogen which affects potatoes. Due to unavailability of effective chemical control methods and the intensive use of fungicides, the introduction of resistant cultivars represents a safe strategy. The... more

Potato Late Blight is the main pathogen which affects potatoes. Due to unavailability of effective chemical control methods and the intensive use of fungicides, the introduction of resistant cultivars represents a safe strategy. The sources of horizontal resistance to Late Blight in the Argentinean Potato Breeding Programs have been varied. One of the interesting species to evaluate is Solanum tarijense since its adaptation to long days is promissory, producing tubers of good size and aspect. In this study, the enzymatic activity of different PR proteins in the specie S. tarijense was measured. These clones were more resistant to Late Blight than 'Bintje' and 'Pampeana INTA' cultivars. The activity of glucanases, chitinases, peroxidases and polyphenoloxidases were 15, 1.5, 2 and 3 times higher respectively, in S. tarijense than in 'Bintje' and 'Pampeana INTA'. These results suggest that some PR proteins can be used as biochemical markers to assist breeders in the selection of horizontal resistant cultivars.

Three subfamilies of grasses, the Erhardtoideae (rice), the Panicoideae (maize, sorghum, sugar cane and millet), and the Pooideae (wheat, barley and cool season forage grasses) provide the basis of human nutrition and are poised to become... more

Three subfamilies of grasses, the Erhardtoideae (rice), the Panicoideae (maize, sorghum, sugar cane and millet), and the Pooideae (wheat, barley and cool season forage grasses) provide the basis of human nutrition and are poised to become major sources of renewable energy. Here we describe the complete genome sequence of the wild grass Brachypodium distachyon (Brachypodium), the first member of the Pooideae subfamily to be completely sequenced. Comparison of the Brachypodium, rice and sorghum genomes reveals a precise sequence- based history of genome evolution across a broad diversity of the grass family and identifies nested insertions of whole chromosomes into centromeric regions as a predominant mechanism driving chromosome evolution in the grasses. The relatively compact genome of Brachypodium is maintained by a balance of retroelement replication and loss. The complete genome sequence of Brachypodium, coupled to its exceptional promise as a model system for grass research, wil...

The investigation was carried out at the laboratory of Plant Pathology Department, SASRD, Nagaland University (NU), Medziphema Campus, Nagaland, India during the year kharif (August-October, 2020) to evaluate the antagonistic potentiality... more

The investigation was carried out at the laboratory of Plant Pathology Department, SASRD, Nagaland University (NU), Medziphema Campus, Nagaland, India during the year kharif (August-October, 2020) to evaluate the antagonistic potentiality of Trichoderma spp. (T. harzianum, T. asperellum and T. virens) against three diseases of pigeonpea viz. Alternaria leaf spot (Alternaria alternata), Collar rot (Sclerotium rolfsii), Phytophthora blight (Phytophthora drechsleri f. sp. cajani). Dual culture technique was followed to test the efficacy of these antagonists as bio-agents against the pathogens. Result of in vitro screening test revealed that all the bio-agents significantly inhibited the mycelial growth of the pathogens. Among the three Trichoderma spp. evaluated, T. harzianum (55.53%) was found to be the highest in per cent inhibition of A. alternata, T. asperellum (50.87 %) recorded highest per cent inhibition on S. rolfsii and T. virens (55.88%) recorded highest per cent inhibition o...

The Green Revolution dwarfing genes, Rht-B1b and Rht-D1b, encode mutant forms of DELLA proteins and are present in most modern wheat varieties. DELLA proteins have been implicated in the response to biotic stress in the model plant,... more

The Green Revolution dwarfing genes, Rht-B1b and Rht-D1b, encode mutant forms of DELLA proteins and are present in most modern wheat varieties. DELLA proteins have been implicated in the response to biotic stress in the model plant, Arabidopsis thaliana. Using defined wheat Rht near-isogenic lines and barley Sln1 gain of function (GoF) and loss of function (LoF) lines, the role of DELLA in response to biotic stress was investigated in pathosystems representing contrasting trophic styles (biotrophic, hemibiotrophic, and necrotrophic). GoF mutant alleles in wheat and barley confer a resistance trade-off with increased susceptibility to biotrophic pathogens and increased resistance to necrotrophic pathogens whilst the converse was conferred by a LoF mutant allele. The polyploid nature of the wheat genome buffered the effect of single Rht GoF mutations relative to barley (diploid), particularly in respect of increased susceptibility to biotrophic pathogens. A role for DELLA in controlling cell death responses is proposed. Similar to Arabidopsis, a resistance trade-off to pathogens with contrasting pathogenic lifestyles has been identified in monocotyledonous cereal species. Appreciation of the pleiotropic role of DELLA in biotic stress responses in cereals has implications for plant breeding.

Legumes can meet their nitrogen requirements through root nodule symbiosis, which could also trigger plant systemic resistance against pests. The pea aphid Acyrthosiphon pisum , a legume pest, can harbour different facultative symbionts... more

Legumes can meet their nitrogen requirements through root nodule symbiosis, which could also trigger plant systemic resistance against pests. The pea aphid Acyrthosiphon pisum , a legume pest, can harbour different facultative symbionts (FS) influencing various traits of their hosts. It is therefore worth determining if and how the symbionts of the plant and the aphid modulate their interaction. We used different pea aphid lines without FS or with a single one ( Hamiltonella defensa , Regiella insecticola, Serratia symbiotica ) to infest Medicago truncatula plants inoculated with Sinorhizobium meliloti (symbiotic nitrogen fixation, SNF) or supplemented with nitrate (non-inoculated, NI). The growth of SNF and NI plants was reduced by aphid infestation, while aphid weight (but not survival) was lowered on SNF compared to NI plants. Aphids strongly affected the plant nitrogen fixation depending on their symbiotic status, suggesting indirect relationships between aphid- and plant-associ...

Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite... more

Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genomewide transcriptional changes in both spider mite and tomato as a consequence of mite's adaptation to tomato. We transferred a genetically diverse mite population from bean to tomato where triplicated populations were allowed to propagate for 30 generations. Evolving populations greatly increased their reproductive performance on tomato relative to their progenitors when reared under identical conditions, indicative of genetic adaptation. Analysis of transcriptional changes associated with mite adaptation to tomato revealed two main components. First, adaptation resulted in a set of mite genes that were constitutively downregulated, in...

Cecropia peltata L. is a myrmecophyte, with a wide distribution in the neotropics, predominantly associated with ants of the genus Azteca. It has been shown that Azteca ants defend Cecropia plants against herbivores, and that the plants... more

Cecropia peltata L. is a myrmecophyte, with a wide distribution in the neotropics, predominantly associated with ants of the genus Azteca. It has been shown that Azteca ants defend Cecropia plants against herbivores, and that the plants provide housing (hollow stems) and food (Müllerian bodies) for the ant colony. In the field, occupation by ants does not take place until

Defenses induced by herbivore feeding or phytohormones such as methyl jasmonate (MeJA) can affect growth, reproduction, and herbivory, not only on the affected individual but also in its neighboring plants. Here, we report multiannual... more

Defenses induced by herbivore feeding or phytohormones such as methyl jasmonate (MeJA) can affect growth, reproduction, and herbivory, not only on the affected individual but also in its neighboring plants. Here, we report multiannual defense, growth, and reproductive responses of MeJA‐treated bilberry (Vaccinium myrtillus) and neighboring ramets. In a boreal forest in western Norway, we treated bilberry ramets with MeJA and water (control) and measured responses over three consecutive years. We observed the treatment effects on variables associated with herbivory, growth, and reproduction in the MeJA‐treated and untreated ramet and neighboring ramets distanced from 10 to 500 cm. MeJA‐treated ramets had fewer grazed leaves and browsed shoots compared to control, with higher effects in 2014 and 2015, respectively. In 2013, growth of control ramets was greater than MeJA‐treated ramets. However, MeJA‐treated ramets had more flowers and berries than control ramets 2 years after the trea...

The interactions between aphids and their host plants seem to be analogous to those of plant-microbial pathogens. Unlike microbial pathogen effectors, little is known about aphid effectors and their ability to interfere with host... more

The interactions between aphids and their host plants seem to be analogous to those of plant-microbial pathogens. Unlike microbial pathogen effectors, little is known about aphid effectors and their ability to interfere with host immunity. To date, only three functional aphid effectors have been reported. To identify potato aphid (Macrosiphum euphorbiae) effectors, we developed a salivary gland transcriptome using Illumina technology. We generated 85 million Illumina reads from salivary glands and assembled them into 646 contigs. Ab initio sequence analysis predicted secretion signal peptides in 24% of these sequences, suggesting that they might be secreted into the plant during aphid feeding. Eight of these candidate effectors with secretion signal peptides were functionally characterized using Agrobacterium tumefaciens–mediated transient overexpression in Nicotiana benthamiana. Two candidate effectors, Me10 and Me23, increased aphid fecundity, suggesting their ability to suppress ...

Plants allocate defences in order to decrease costs and maximize benefits against herbivores. The Optimal Defense Theory (ODT) predicts that continuously expressed (i.e. constitutive) defences are expected in structures of high value,... more

Plants allocate defences in order to decrease costs and maximize benefits against herbivores. The Optimal Defense Theory (ODT) predicts that continuously expressed (i.e. constitutive) defences are expected in structures of high value, whereas defences that are expressed or that increase their expression only after damage or upon risk of damage (i.e. induced defences) are expected in structures of low value. Although there are several studies evaluating ODT predictions, few studies have successfully tested them as a way of measuring ecological investment in extrafloral nectary (EFN)‐mediated ant–plant interactions. Here we compared extrafloral nectar production and ant attractiveness to EFNs located on vegetative versus reproductive plant structures on Qualea multiflora plants subjected to different levels of simulated herbivory. We then addressed the following predictions emerging from the ODT: (a) extrafloral nectar produced in inflorescence EFNs will have higher volumes and calori...