Functional genomics and molecular genetics of the legume-powdery mildew interaction

Food legumes represent major crops cultivated and consumed in India and other developing countries due to their high nutritional value and important role in maintaining the ecosystem. Powdery mildew is one of the most devastating fungal diseases limiting legume productivity in India. These obligate biotrophs alter plant cellular architecture and metabolism to acquire nutrients via specialized feeding structures (haustoria) while limiting plant defense responses. Chemical treatments used to control the disease are neither economical nor sustainable. Furthermore, despite the availability of a few powdery mildew resistant legume varieties, identity of the genes conferring resistance and knowledge of the underlying molecular events is limited.

Our main goal is to identify novel plant host genes that limit powdery mildew growth with no associated yield penalty and introduce them into agronomically important food legumes to increase durable resistance. We will integrate infection site-specific analyses, functional genomics and molecular genetics in the Medicago truncatula-Erysiphe pisi model system to identify novel host factors that limit powdery mildew growth at different developmental stages and translate functionally verified targets into food legumes. We envisage that factors able to limit pathogen growth at different developmental stages would be more difficult to overcome than resistance based on a single mechanism or mechanisms governed by a single gene.

Another major area of focus is to elucidate how obligate biotrophs modulate host metabolism to divert nutrients, especially sugars from the host plant for their sustained growth. We will utilize the Medicago -Erysiphe pathosystem to identify pathogen-induced molecular components of carbohydrate sink strength at the powdery mildew infection site. We will combine infection site-specific profiling, promoter, co-expression and gene ontology enrichment analyses to identify regulators of this process and construct putative regulatory networks with testable hypotheses. Using these approaches, we expect to identify key players modulating carbon (re)allocation at the infection site.

• Dr. Raghavendra Aminedi
  Young Investigator
  raghu.aminedi@rcb.res.in
• Gunjan Sharma
  SERB National Postdoctoral Fellow
  gunjan@rcb.res.in
• Megha Gupta
  Senior Research Fellow
  megha.gupta@rcb.res.in
• Arunima Gupta
  Junior Research Fellow
  arunima.gupta@rcb.res.in
• Akriti Sharma
  Junior Research Fellow
  akriti@rcb.res.in
• Varsha Gupta
  Junior Research Fellow
  varsha.gupta@rcb.res.in

1. Wildermuth MC, Steinwand MA, McRae AG, Jaenisch J, Chandran D (2017) Adapted Biotroph Manipulation of Plant Cell Ploidy. Annu Rev Phytopathol 55:564
2. Chandran D, Wildermuth MC (2016) Modulation of Host Endocycle During Plant-Biotroph Interactions. Enzymes 40:65
3. Chandran D, Scanlon MJ, Ohtsu K, Timmermans MC, Schnable PS, Wildermuth MC (2015)  Laser Microdissection-Mediated Isolation and In Vitro Transcriptional Amplification of Plant RNA. Curr Protoc Mol Biol. 112:25A.3.1
4. Chandran D (2015)  Co-option of developmentally regulated plant SWEET transporters for pathogen nutrition and abiotic stress tolerance. IUBMB Life 67:461
5. Chandran D, Rickert J, Huang Y, Steinwand M, Marr SK, Wildermuth MC. (2014) Atypical E2F Transcriptional Repressor DEL1 Acts at the Intersection of Plant Growth and Immunity by Controlling the Hormone Salicylic Acid. Cell Host & Microbe 15: 506.
6. Chandran D, Rickert J, Cherk C, Dotson B, Wildermuth MC. (2013) Host cell ploidy underlying the fungal feeding site is a determinant of powdery mildew growth and reproduction. Molecular Plant-Microbe Interactions, 26(5):537.
7. Chandran D, Hather G, Wildermuth MC. (2011) Global expression profiling of RNA from laser microdissected cells at fungal-plant interaction sites. Methods in Molecular Biology: Plant Immunity (ed. J. McDowell) 712:263.
8. Chandran D, Inada N, Wildermuth MC. (2011) Laser microdissection of plant-fungus interaction sites and isolation of RNA for downstream expression profiling. Methods in Molecular Biology: Plant Immunity (ed. J. McDowell) 712:241.
9. Ford KA, Casida JE, Chandran D, Gulevich AG, Okrent RA, Durkin KA, Sarpong R, Bunnelle EM, Wildermuth MC. (2010). Neonicotinoid insecticides induce salicylate-associated plant defense responses. Proceedings of the National Academy of Sciences USA 107:17527.
10. Chandran D, Inada N, Hather G, Kleindt CK, Wildermuth MC. (2010) Laser microdissection of Arabidopsis cells at the powdery mildew infection site reveals site-specific processes and regulators. Proceedings of the National Academy of Sciences USA107:460.
11. Chandran D, Tai YC, Hather G, Dewdney JD, Denoux C, Burgess DG, Ausubel FM, Speed TP, Wildermuth MC. (2009) Temporal global expression data reveals known and novel salicylate-impacted processes and regulators mediating powdery mildew growth and reproduction on Arabidopsis. Plant Physiology 149:1435.
12. Chandran D, Sharopova N, VandenBosch KA, Garvin DF, Samac DA. (2008) Physiological and molecular characterization of aluminum resistance in Medicago truncatula. BMC Plant Biology 8:89.
13. Chandran D, Sharopova N , Ivashuta S, VandenBosch KA, Gantt S, Samac DA. (2008) Transcriptome profiling identified novel genes associated with aluminum toxicity, resistance and tolerance in Medicago truncatula. Planta 228(1):151.
14. Chandran D, Reinders A, Ward JM. (2003) Substrate specificity of the Arabidopsis thaliana sucrose transporter AtSUC2. Journal ofBiological Chemistry. 278(45):44320.