scholarly journals Glucosinolate Biosynthesis and the Glucosinolate–Myrosinase System in Plant Defense

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1786
Author(s):  
Shweta Chhajed ◽  
Islam Mostafa ◽  
Yan He ◽  
Maged Abou-Hashem ◽  
Maher El-Domiaty ◽  
...  
Keyword(s):  
Plant Defense ◽  
Defense Mechanisms ◽  
Insect Pests ◽  
Degradation Products ◽  
Insect Herbivory ◽  
Mustard Oil ◽  
Glucosinolate Biosynthesis ◽  
Global Challenge ◽  
Natural Defense ◽  
Hydrolyzing Enzymes

Insect pests represent a major global challenge to important agricultural crops. Insecticides are often applied to combat such pests, but their use has caused additional challenges such as environmental contamination and human health issues. Over millions of years, plants have evolved natural defense mechanisms to overcome insect pests and pathogens. One such mechanism is the production of natural repellents or specialized metabolites like glucosinolates. There are three types of glucosinolates produced in the order Brassicales: aliphatic, indole, and benzenic glucosinolates. Upon insect herbivory, a “mustard oil bomb” consisting of glucosinolates and their hydrolyzing enzymes (myrosinases) is triggered to release toxic degradation products that act as insect deterrents. This review aims to provide a comprehensive summary of glucosinolate biosynthesis, the “mustard oil bomb”, and how these metabolites function in plant defense against pathogens and insects. Understanding these defense mechanisms will not only allow us to harness the benefits of this group of natural metabolites for enhancing pest control in Brassicales crops but also to transfer the “mustard oil bomb” to non-glucosinolate producing crops to boost their defense and thereby reduce the use of chemical pesticides.

Morphophysiological basis of plant defense mechanisms against insect pests

2020 ◽  
Vol 44 (1) ◽  
pp. 171
Author(s):  
Shimantini Borkataki ◽  
S.P. Nanda ◽  
M. Devender Reddy ◽  
Ritu Ranjan Taye
Keyword(s):  
Plant Defense ◽  
Defense Mechanisms ◽  
Insect Pests

scholarly journals The Role of Arabinogalactan Type II Degradation in Plant-Microbe Interactions

2021 ◽  
Vol 12 ◽  
Author(s):  
Maria Guadalupe Villa-Rivera ◽  
Horacio Cano-Camacho ◽  
Everardo López-Romero ◽  
María Guadalupe Zavala-Páramo
Keyword(s):  
Cell Wall ◽  
Plant Defense ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Degradation Products ◽  
Hydrolytic Enzymes ◽  
Pathogenic Fungi ◽  
Plant Interactions ◽  
Root Tips ◽  
Microbe Interactions

Arabinogalactans (AGs) are structural polysaccharides of the plant cell wall. A small proportion of the AGs are associated with hemicellulose and pectin. Furthermore, AGs are associated with proteins forming the so-called arabinogalactan proteins (AGPs), which can be found in the plant cell wall or attached through a glycosylphosphatidylinositol (GPI) anchor to the plasma membrane. AGPs are a family of highly glycosylated proteins grouped with cell wall proteins rich in hydroxyproline. These glycoproteins have important and diverse functions in plants, such as growth, cellular differentiation, signaling, and microbe-plant interactions, and several reports suggest that carbohydrate components are crucial for AGP functions. In beneficial plant-microbe interactions, AGPs attract symbiotic species of fungi or bacteria, promote the development of infectious structures and the colonization of root tips, and furthermore, these interactions can activate plant defense mechanisms. On the other hand, plants secrete and accumulate AGPs at infection sites, creating cross-links with pectin. As part of the plant cell wall degradation machinery, beneficial and pathogenic fungi and bacteria can produce the enzymes necessary for the complete depolymerization of AGs including endo-β-(1,3), β-(1,4) and β-(1,6)-galactanases, β-(1,3/1,6) galactanases, α-L-arabinofuranosidases, β-L-arabinopyranosidases, and β-D-glucuronidases. These hydrolytic enzymes are secreted during plant-pathogen interactions and could have implications for the function of AGPs. It has been proposed that AGPs could prevent infection by pathogenic microorganisms because their degradation products generated by hydrolytic enzymes of pathogens function as damage-associated molecular patterns (DAMPs) eliciting the plant defense response. In this review, we describe the structure and function of AGs and AGPs as components of the plant cell wall. Additionally, we describe the set of enzymes secreted by microorganisms to degrade AGs from AGPs and its possible implication for plant-microbe interactions.

scholarly journals The race goes on: A fall armyworm-resistant maize inbred line influences insect oral secretion elicitation activity and nullifies herbivore suppression of plant defense

2021 ◽  
Author(s):  
Saif ul Malook ◽  
Xiao-Feng Liu ◽  
Wende Liu ◽  
Jinfeng Qi ◽  
Shaoqun Zhou
Keyword(s):  
Plant Defense ◽  
Host Plant ◽  
Inbred Line ◽  
Defense Mechanisms ◽  
Molecular Mechanisms ◽  
Fall Armyworm ◽  
Defense Responses ◽  
Feeding Preference ◽  
Maize Inbred Line ◽  
Oral Secretion

Fall armyworm (Spodoptera frugiperda) is an invasive lepidopteran pest with strong feeding preference towards maize (Zea mays). Its success on maize is facilitated by a suite of specialized detoxification and manipulation mechanisms that curtail host plant defense responses. In this study, we identified a Chinese maize inbred line Xi502 that was able to mount effective defense in response to fall armyworm attack. Comparative transcriptomics analyses, phytohormonal measurements, and targeted benzoxazinoid quantification consistently demonstrate significant inducible defense responses in Xi502, but not in the susceptible reference inbred line B73. In 24 hours, fall armyworm larvae feeding on B73 showed accelerated maturation-oriented transcriptomic responses and more changes in detoxification gene expression compared to their Xi502-fed sibling. Interestingly, oral secretions collected from larvae fed on B73 and Xi502 leaves demonstrated distinct elicitation activity when applied on either host genotypes, suggesting that variation in both insect oral secretion composition and host plant alleles could influence plant defense response. These results revealed host plant adaptation towards counter-defense mechanisms in a specialist insect herbivore, adding yet another layer to the evolutionary arms race between maize and fall armyworm. This could facilitate future investigation into the molecular mechanisms in this globally important crop-pest interaction system.

scholarly journals Strong Sour Tamarind Flavor of Methyl-2,3,4- trihydroxyhexanoate, a new compound isolated from Leaves of Tamarindus indica, L. plays a role in plant defense mechanisms

2012 ◽  
pp. 26-44
Author(s):  
Suprana Biswas ◽  
Nabanita Chakraborty ◽  
Supriya Chakraborty
Keyword(s):  
Antioxidant Activity ◽  
Plant Defense ◽  
Inhibitory Activity ◽  
Defense Mechanisms ◽  
Defense Mechanism ◽  
Aspergillus Tamarii ◽  
Methanol Fraction ◽  
Wide Range ◽  
Plant Defense Mechanism ◽  
Defensive Activity

Flavoring compounds of plants play a significant role in plant defense mechanism. Compound responsible for strong sour tamarind flavor has been isolated and identified from Methanol fraction of tamarind leaves (TrMF). Chromatographic and spectral analyses of TrMF revealed the compound to be methyl 2,3,4- trihydroxyhexanoate. This compound showed a strong antioxidant activity as well as strong antimicrobial activity. It showed significant antioxidant activity with Ic50 value of 2.5μg/ml whereas tert-butyl-1-hydroxytoluene and ascorbic acid revealed 26.0μg/ml and 5.0μg/ml, respectively. It also revealed strong inhibitory activity against Aspergellosis disease-causing fungi namely; Aspergillus fumigatus, Aspergillus tamarii and Aspergillus niger at all concentrations. Streptococcus aureus and Escherichia coli were much more sensitive to methyl-trihydroxy-hexanoate at all concentrations than Pseudomonas aeruginosa. This pure compound exhibited concentration dependent inhibitory and stimulatory activity on rice seeds germination and seedling growth. It showed strong inhibitory activity up to 62.5ppm concentration and below this concentration the effect was stimulatory. Methyl- trihydroxyhexanoate exhibited wide range of defensive activity against microbes and crop seeds and also possesses potent antioxidative activity. Thus play an important role in plant defense mechanism and can be utilized as a valuable source of bio-herbicides and pesticides.

scholarly journals The Arabidopsis PAD4 Lipase-Like Domain Is Sufficient for Resistance to Green Peach Aphid

2020 ◽  
Vol 33 (2) ◽  
pp. 328-335 ◽  
Author(s):  
Joram A. Dongus ◽  
Deepak D. Bhandari ◽  
Monika Patel ◽  
Lani Archer ◽  
Lucas Dijkgraaf ◽  
...  
Keyword(s):  
Plant Defense ◽  
Insect Pests ◽  
Green Peach Aphid ◽  
Aphid Resistance ◽  
Molecular Evidence ◽  
Immune Functions ◽  
Transgenic Expression ◽  
Domain Specific ◽  
Pathogenic Microbes

Plants have evolved mechanisms to protect themselves against pathogenic microbes and insect pests. In Arabidopsis, the immune regulator PAD4 functions with its cognate partner EDS1 to limit pathogen growth. PAD4, independently of EDS1, reduces infestation by green peach aphid (GPA). How PAD4 regulates these defense outputs is unclear. By expressing the N-terminal PAD4 lipase-like domain (PAD4LLD) without its C-terminal EDS1-PAD4 (EP) domain, we interrogated PAD4 functions in plant defense. Here, we show that transgenic expression of PAD4LLD in Arabidopsis is sufficient for limiting GPA infestation but not for conferring basal and effector-triggered pathogen immunity. This suggests that the C-terminal PAD4 EP domain is necessary for EDS1-dependent immune functions but is dispensable for aphid resistance. Moreover, PAD4LLD is not sufficient to interact with EDS1, indicating the PAD4-EP domain is required for stable heterodimerization. These data provide molecular evidence that PAD4 has domain-specific functions.

scholarly journals Genetic Basis of Maize Resistance to Multiple Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization

Genes ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 689
Author(s):  
A. Badji ◽  
D. B. Kwemoi ◽  
L. Machida ◽  
D. Okii ◽  
N. Mwila ◽  
...  
Keyword(s):  
Insect Resistance ◽  
Defense Mechanisms ◽  
Genome Wide Association Study ◽  
Insect Pests ◽  
Physical Map ◽  
Fall Armyworm ◽  
Nucleotide Polymorphisms ◽  
Multiple Traits ◽  
Maize Weevil ◽  
Genome Wide

Several species of herbivores feed on maize in field and storage setups, making the development of multiple insect resistance a critical breeding target. In this study, an association mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and genotyped with Diversity Array Technology’s single nucleotide polymorphisms (SNPs) markers. A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides (QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which, 47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01, respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs) concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated with resistance to both FAW and MW, suggesting a pleiotropic genetic control. Functional prioritization of candidate genes (CGs) located within 10–30 kb of the QTNs revealed 64 putative GWAS-based CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG was associated with each of the five of the six combined resistance QTNs, thus reinforcing the pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional 107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and differentially expressed under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance physical map should contribute to the development of combined insect resistance in maize.

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