Dr. Kranthi Kiran Mandadi
Dept. Plant Pathology and Microbiology
Lab Site: sites.google.com/a/tamu.edu/mandadi-lab/
Ph.D., Texas A&M University, 2010
M.S., Texas A&M University-Kingsville, 2005
B.S., A.N.G.R. Agricultural University, India, 2002
Plant biology and stress omics
World-wide, pathogens, insects and abiotic stresses cause major losses in yield and quality of crops. My lab employs systems approaches for basic and translational studies of plant stress responses in both model (e.g., Brachypodium, Setaria and Arabidopsis) and crop (e.g., Citrus, Sugarcane, tomato and potato) plants. We are using the latest omics and bioinformatics tools to establish and utilize integrative knowledge-bases for diverse plant abiotic (drought, heat, cold, salinity and nutrient deficiency or toxicity) and biotic (viral, fungal, bacterial and insect) stress conditions. The knowledge-bases are valuable resources for data mining and discovery of critical gene modules and molecular markers useful for crop improvement via biotechnology and breeding, as well as to understand plant genotype-to-phenotype relationships.
Plant-Microbe Interactions and Immune Signaling
Plant defense responses against viral, fungal and bacterial infections involve intricate networking of multitude of defense-associated genes and signaling pathways. However, very little is known about the gene regulatory networks that function in grass defenses, despite grasses being the primary sources of our calories. To enable fundamental studies of cereal and bioenergy grass defense pathways, we established Brachypodium distachyon (a C3 grass) and Setaria viridis (a C4 grass) as basic research models for the agronomic grasses. Using these models, we recently characterized the transcriptome-, spliceome- and metabolome-level changes occurring during diverse grass:viral infections. From these studies, we identified approximately thirty receptor-like kinases (RLKs) in several sub-families including multiple pattern recognition receptors (PRRs), defense hormone-related genes, transcription factors (WRKY, MYB and AP2/ERF family), protein synthesis- and degradation-related proteins that are mis-expressed. Each of these proteins could influence plant immune responses. Currently, we are determining how the RLK and the transcription factors function in mediating grass defenses using genetic, molecular and biochemical approaches. The findings will not only advance our fundamental knowledge of grass biotic stress signaling pathways, but also lead to innovative strategies of bioenergy and cereal crop improvement to resist diseases.
Understanding Mechanisms of Plant Central Stress Regulators
Central stress regulators are an emerging signaling concept, where in few core genes respond to, and integrate multiple stress signals to promote tolerance against diverse stresses. We recently discovered a central stress regulator, BT2, which mediates responses to diverse biotic and abiotic stresses, nutrient, environment and hormone signals. We are currently pursuing functional characterization of BT2 signaling network in Arabidopsis. The BT2 signaling pathway is composed of other proteins including CULLIN3, GTE9/BET9 and GTE11/BET10 (Misra et al., in-preparation), as well as, BT2 homologs, BT1, BT3, BT4 and BT5 (Mandadi et al., in-preparation). BT family proteins, including BT2, are hypothesized to assemble into distinct ubiquitin ligases that target specific proteins for ubiquitin-mediated proteolysis. GTE9 and GTE11 are also putative acetyl-histone binding bromodomain proteins, and they physically interact with BT2 in yeast 2-hybrid and in vitro co-IP interaction assays. We have recently discovered that BT2 suppresses DNA methylation and promotes transcription mediated by viral enhancers. It is possible that the BT2 ubiquitin ligase targets specific proteins in transcription processes such as transcriptional activators, repressors and/or chromatin remodeling factors for degradation by polyubuiquitilation, and may influence DNA methylation process. We will further determine the interactions of BT-family ubiquitin ligase components in vivo, and identify their cellular targets using biochemical and cell-biological techniques such as immunoprecipitation and approaches to identify the targets of BT-family ubiquitin ligases. Further, using genomic tools such as RNA-sequencing and/or 2-D proteomics, we will initiate genome-wide expression studies of genetic loss-of-function and gain-of-function of genes in BT2 network.
Crop Improvement by Deploying Central Stress Regulators
We are pursuing novel strategies to improve crop tolerances against diverse physiological, biotic and abiotic stress signals by modulating activity of specific central stress regulators like BT2. BT2-like genes are well conserved in food and bioenergy crops. We are undertaking identification, characterization and activation of such crop central stress regulators in Citrus, tomato, potato, sugarcane, and energycane using comparative genomics and molecular phylogenetics approaches. The discovered genes are incorporated into a pipeline of crop transformation and breeding at the Texas A&M AgriLife Research and Extension center-Weslaco. The ultimate goal is to develop robust stress tolerances without compromising agronomic qualities.
Citrus, Sugarcane and Energycane Improvement
We are using comparative genomics, phylogenetics and bioinformatics methods to data-mine existing plant genome databases in order to discover novel anti-microbial and resistance-imparting genes. Through collaborations with Dr. Erik Mirkov (Professor, Texas A&M AgriLife), and Dr. Jorge da Silva (Professor, Texas A&M AgriLife), the novel genes are deployed into Citrus and sugarcane by genetic engineering and molecular marker-assisted breeding. Specific projects are underway to develop resistance against citrus greening/Huanglongbing, potato zebrachip, as well as sugarcane and energycane infecting pathogens and insects.
Mandadi, K.K. and Scholthof, K-B.G. (2015) Genome-wide analysis of alternative splicing landscapes modulated during plant-virus interactions in Brachypodium distachyon. Plant Cell (in press). FRONT SECTION FEATURE/LARGE SCALE BIOLOGY
Mandadi K.K., Pyle, J.D., and Scholthof, K-B.G. (2014) Comparative analysis of antiviral responses in Brachypodium distachyon and Setaria viridis reveal conserved and unique outcomes among C3 and C4 plant defenses. Mol. Plant Microbe Interact. 27, 1277-1290.
Mandadi, K.K., and Scholthof, K-B.G. (2013) Plant immune responses against viruses: How does a virus cause disease? Plant Cell 25, 1489–1505
Góngora-Castillo, E., Childs, K.L., Fedewa, G., Hamilton, J.P., Liscombe, D.K., Magallanes, M., Mandadi, K., Nims, N.E., Runguphan, W., Vaillancourt, B., Varbanova, M., DellaPenna, D., McKnight, T., O’Connor, S., and Buell, C.R. (2012). Development of transcriptomic resources for interrogating the biosynthesis of monoterpene indole alkaloids in medicinal plant species. PLoS ONE 7(12): e52506
Mandadi, K.K., and Scholthof, K.-B.G. (2012). Characterization of a viral synergism in the monocot Brachypodium reveals distinctly altered host molecular processes associated with disease. Plant Physiol. 160, 1432-1452.
Mandadi, K.K., Misra, A., Ren, S., and McKnight, T.D. (2009) BT2 mediates multiple responses to nutrients, stresses and hormones in Arabidopsis thaliana. Plant Physiol. 150, 1930-1939.
Ren, S., Mandadi, K.K., Boedeker, A.L., Rathore, K.S., and McKnight, T.D. (2007) Regulation of telomerase in Arabidopsis by BT2, an apparent target of the TELOMERASE ACTIVATOR1. Plant Cell 19, 23-31.
Mandadi, K., Ramirez, M., Jayaprakasha, G.K., Faraji, B., Lihono, M., Deyhim, F., and Patil B.S. (2009) Citrus bioactive compounds improve bone quality and plasma antioxidant activity in orchidectomized rats. Phytomedicine 16(6-7), 513-520.
Deyhim, F., Mandadi, K., Faraji, B and Patil B.S. (2008) Grapefruit juice modulates bone quality in rats. J. Med. Food 11, 99-104.
Deyhim, F., Mandadi, K., Faraji, B and Patil B.S. (2008) Grapefruit pulp increases antioxidant status and improves bone quality in orchidectomized rats. Nutrition 24, 1039-1044.
Jayaprakasha, G.K., Mandadi, K.K., Poulose, S.M., Jadegoud, Y., Nagana Gowda, G.A., and Patil, B.S. (2008) Novel triterpinoid from Citrus aurantium L. possess chemopreventive properties against human colon cancer cells. Bioorg. Med. Chem. 16, 5939-5951.
Deyhim, F., Villarreal, A., Garcia, K., Rios, R., Garcia, C., Gonzales, C., Mandadi, K., and Patil, B.S. (2007) Orange pulp improves antioxidant status and suppresses lipid peroxidation in orchidectomized male rats. Nutrition 23, 617-621.
Mandadi, K.K., Jayaprakasha, G.K., Bhat, N., and Patil, B.S. (2007) Red Mexican Grapefruit: A novel source for bioactive limonoids and their antioxidant activity. Z. Naturforschung 62C, 179.
Jayaprakasha, G.K., Mandadi, K.K., Poulose, S.M., Jadegoud, Y., Nagana Gowda, G.A., and Patil, B.S. (2007) Inhibition of colon cancer cell growth and antioxidant activity of bioactive compounds from Poncirus trifoliata (L.) Raf. Bioorg. Med. Chem. 15, 4923-4932.
Villarreal, A., Stoecker, B.J., Garcia, C., Garcia, K., Rios, R., Gonzales, C., Mandadi, K., Faraji, B., Patil, B.S., and Deyhim, F. (2007) Cranberry juice improved antioxidant status without affecting bone quality in orchidectomized male rats. Phytomedicine 10, 49-53.
Deyhim, F., Rios, R., Garcia, C., Villarreal, A., Garcia, K., Gonzales, C., Mandadi, K., Faraji, B., and Patil, B.S. (2007) Orange pulp increases antioxidant status and improves bone quality in orchidectomized rats. Curr. Nutr. Food Sci. 3, 319-323.
Deyhim, F., Garcia, C., Villarreal, A., Garcia, K., Rios, R., Gonzales, C., Mandadi, K., Faraji, B., and Patil, B.S. (2007) Vitamin E does not support bone quality in orchidectomized rats. Curr. Nutr. Food Sci. 3, 300-303.
Deyhim, F., Gonzales, C., Villarreal, A., Garcia, K., Rios, R., Garcia, C., Mandadi, K., and Patil, B.S. (2007) Vitamin E does not modulate plasma cholesterol, triglyceride, or C-reactive protein despite suppressing oxidative stress in orchidectomized rats. J. Med. Food 10, 559-562.
Deyhim, F., Patil, B.S., Villarreal, A., Lopez, E., Garcia, K., Rios, R., Garcia, C., Gonzales, C., and Mandadi, K. (2007) Cranberry juice increases antioxidant status without affecting cholesterol homeostasis in orchidectomized rats. J. Med. Food 10, 49-53.