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Arabidopsis thaliana--Myzus persicae interaction: shaping the understanding of plant defense against phloem-feeding aphids

Description: This review article summarizes recent studies that have exploited the compatible interaction between Arabidopsis and the green peach aphid (GPA) to understand the molecular and physiological mechanisms utilized by plants to control aphid infestation, as well as genes and mechanisms that contribute to susceptibility.
Date: July 1, 2013
Creator: Louis, Joe & Shah, Jyoti
Partner: UNT College of Arts and Sciences

Metabolic engineering of raffinose-family oligosaccharides in the phloem reveals alterations in carbon partitioning and enhances resistance to green peach aphid

Description: This article discusses the use of metabolic engineering to generate raffinose-family oligosaccharides (RFOs) at the inception of the translocation stream of Arabidopsis thaliana, which loads from the apoplasm and transports predominantly sucrose, and the fate of the sugars through the plant determined.
Date: July 19, 2013
Creator: Cao, Te; Lahiri, Ipsita; Singh, Vijay; Louis, Joe; Shah, Jyoti & Ayre, Brian G.
Partner: UNT College of Arts and Sciences

9-Lipoxygenase Oxylipin Pathway in Plant Response to Biotic Stress

Description: The activity of plant 9-lipoxygenases (LOXs) influences the outcome of Arabidopsis thaliana interaction with pathogen and insects. Evidence provided here indicates that in Arabidopsis, 9-LOXs facilitate infestation by Myzus persicae, commonly known as the green peach aphid (GPA), a sap-sucking insect, and infection by the fungal pathogen Fusarium graminearum. in comparison to the wild-type plant, lox5 mutants, which are deficient in a 9-lipoxygenase, GPA population was smaller and the insect spent less time feeding from sieve elements and xylem, thus resulting in reduced water content and fecundity of GPA. LOX5 expression is induced rapidly in roots of GPA-infested plants. This increase in LOX5 expression is paralleled by an increase in LOX5-synthesized oxylipins in the root and petiole exudates of GPA-infested plants. Micrografting experiments demonstrated that GPA population size was smaller on plants in which the roots were of the lox5 mutant genotype. Exogenous treatment of lox5 mutant roots with 9-hydroxyoctadecanoic acid restored water content and population size of GPA on lox5 mutants. Together, these results suggest that LOX5 genotype in roots is critical for facilitating insect infestation of Arabidopsis. in Arabidopsis, 9-LOX function is also required for facilitating infection by F. graminearum, which is a leading cause of Fusarium head blight (FHB) disease in wheat and other small grain crops. Loss of LOX1 and LOX5 function resulted in enhanced resistance to F. graminearum infection. Similarly in wheat, RNA interference mediated silencing of the 9-LOX homolog TaLpx1, resulted in enhanced resistance to F. graminearum. Experiments in Arabidopsis indicate that 9-LOXs promote susceptibility to this fungus by suppressing the activation of salicylic acid-mediated defense responses that are important for basal resistance to this fungus. the lox1 and lox5 mutants were also compromised for systemic acquired resistance (SAR), an inducible defense mechanism that is systemically activated throughout a plant in response to a ...
Date: May 2012
Creator: Nalam, Vamsi J.
Partner: UNT Libraries

Studies on Plant-aphid Interactions: a Novel Role for Trehalose Metabolism in Arabidopsis Defense Against Green Peach Aphid

Description: Myzus persicae (S├╝lzer), commonly known as the green peach aphid (GPA), is a polyphagous insect that can infest over 100 families of economically important plants and is major pest for vegetable crops. This study utilizes the Arabidopsis-GPA model system with the aim to elucidate the role of the plant disaccharide trehalose in providing defense against GPA. This study demonstrates a novel role for TPS11 in providing defense against GPA. TPS11 expression was found to be transiently induced in Arabidopsis plants in response to GPA infestation and the TPS11 gene was required for curtailing GPA infestation. TPS11, which encodes for trehalose phosphate synthase and phosphatase activities, contributes to the transient increase in trehalose in the GPA infested tissues. This work suggests that TPS11-dependent trehalose has a signaling function in plant defense against GPA. in addition, trehalose also has a more direct role in curtailing GPA infestation on Arabidopsis. This work also shows that TPS11 is able to modulate both carbohydrate metabolism and plant defenses in response to GPA infestation. the expression of PAD4, an Arabidopsis gene required for phloem-based defenses against GPA, was found to be delayed in GPA infested tps11 mutant plants along with increased sucrose levels and lower starch levels as compared to the GPA infested wild type plants. This work provides clear evidence that starch metabolism in Arabidopsis is altered in response to GPA feeding and that TPS11-modulated increase in starch contributes to the curtailment of GPA infestation in Arabidopsis.
Date: May 2012
Creator: Singh, Vijay
Partner: UNT Libraries