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Department of Plant Pathology  
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Microbial effector recognition in soybean

  Psg induced HR in soybean

We utilize the soybean-Pseudomonas syringae pv. glycinea (Psg), soybean-soybean mosaic virus, and the soybean-Pseudomonas syringae pathosystems to study the mechanisms of pathogen effector recognition in plants. For example, we have identified a family of related proteins termed GmRIN4a-d for their high sequence similarity to Arabidopsis RIN4, that function in resistance signaling against Psg expressing different avirulence effectors (Avr). These proteins directly interact with Psg Avr proteins as well as at least one resistance (R) protein from soybean. Current efforts are directed towards understanding how this family of proteins enables the specific recognition of unrelated effectors to induce signaling via diverse R loci. We are also studying the targets of viral effector proteins in soybean. In particular, we are interested in characterizing the defense-related roles of host proteins targeted by the P3 effector from soybean mosaic virus.

Functional genomics: soybean fatty acid/triacyl glyceolipid biosynthesis

Increasing evidence suggests a role for components of primary metabolism in regulating plant defense as well as microbial pathogenesis. It is quite likely that primary metabolic pathways in both plant and pathogen interface with disease-related signaling, since the pathogen relies upon host nutrients for survival and thereby successful pathogenicity.

Morphological phenotype of
-silenced plants

Our studies in Arabidopsis have shown that the fatty acid oleic acid (18:1) is an important regulator of defense signaling. We have shown that reduced levels of 18:1 induce the expression of multiple R genes and result in the constitutive activation of defense signaling in Arabidopsis, soybean, and common bean. In addition, glycerol-3-phosphate (G3P) an obligatory precursor of all glycerolipid biosynthesis is also an essential regulator of plant defense. We showed that the ability to rapidly accumulate G3P is important for induced resistance against the hemibiotrophic anthracnose fungus, Colletotrichum higginsianum. Preliminary studies indicate that G3P regulates basal defense to several other pathogens in both Arabidopsis and soybean. More recently we showed that an unidentified derivative of G3P along with the lipid transfer protein DIR1 comprises a crucial mobile inducer of systemic immunity in Arabidopsis and soybean alike.

We have characterized the defense-related functions of soybean genes encoding stearoyl acyl carrier protein desaturase, omega-3-fatty acid desaturases, as well as several enzymes involved in G3P metabolism. To fully characterize the connection between glycerolipid metabolism and defense signaling, we aim to identify and functionally characterize metabolic activities involved in G3P, fatty acid, and triacylglycerolipid biosynthesis.

Altering seed yield



Increased seed size in GmFAD3-silenced plants

This project, funded by the United Soybean Board, involves the identification and functional characterization of soybean genes affecting seed yield and quality. The aim is to identify genes that contribute to seed size and number, as well as protein, fatty acid and oil content, and eventually utilize this information to enhance soybean yield. As an example, we have shown that silencing genes encoding omega-3-fatty acid desaturases in soybean increases seed size and yield in green house grown plants.