Agricultural genomics and subterranean plant-plant communications

Agricultural genomics has the potential to dramatically enrich the availabi lity and quality of food supplies worldwide. However, because thousands of different plant species are grown for food, the application of genomics to crop improvement faces issues distinct from those in medical research. The challenge to agricultural plant scientists is to exploit the. databases bei ng generated for rice, maize, and Arabidopsis toward the genetic improvemen t of non-model crop species. The work in our lab illustrates one example of how genomic approaches can be applied to a non-model plant. Our overall go al is to understand how roots of different plants interact and use this inf ormation to improve the subterranean performance of crops in relation to we eds. The most obvious manifestation of root-root interactions is haustoria development. Haustoria are parasitic plant-specific organs that invade host plants and rob them of water and nutrients. Parasitic members of the Scrop hulariaceae develop haustoria in vitro when exposed to molecules released b y host roots. This is a useful phenotype for investigating plant-plant inte ractions because it is rapid, highly synchronous, and strictly dependent on exogenous haustoria-inducing factors (HIFs). Using a PCR-based subtractive hybridization, we cloned several hundred cDNAs representing transcripts on e to two orders of magnitude more abundant in the roots of a parasitic plan t after HIF exposure. Putative functions for about 90% of these transcripts could be assigned by searching the public databases. These have been array ed on nylon filters and interrogated with a variety of probes from differen t parasitic and nonparasitic plants. Results from these experiments allowed us to identify likely candidate genes for the perception and processing of root signals by neighboring plants. J. Cell. Biochem. 80: 203-207, 2000. ( C) 2000 Wiley-Liss, Inc.