(265) HSP101 in the Model Strawberry Fragaria vesca

Abstract

Our lab has initiated a project to determine if specific proteins expressed by strawberry function as part of the thermotolerance system. We have developed tools for investigating the role of heat shock proteins (HSPs) and other gene products in strawberry thermotolerance. These tools include an inbred diploid testing system, EST sequence data, and molecular markers for heat tolerance. We developed an inbred line, 5AF7, of the diploid strawberry Fragariavesca for testing gene function because the diploid genome is small (164Mbp), the life cycle of the plant is short (about 4 months), the plant size is small (a plant will produce fruit in a 4-inch pot), some genetic work is already done, F. vesca is transformable with Agrobacteriumtumefaciens , and results should be transferable to the commercial octoploid varieties. A cDNA library was constructed in the pCMVsport 6.1 vector using combined RNA from batches of aseptically grown F. vesca seedlings treated to various elevated temperature regimes. Over 1500 EST sequences from the library have been deposited in GenBank and are available annotated at the ESTAP Fragaria database ( http://staff.vbi.vt.edu/estap/index.shtml ). HSP101 affects thermotolerance in Arabidopsis (Queitsch et al., 2000, Plant Cell 12:479). A PCR fragment for HSP101 was generated from F. vesca with degenerate primers, and used to obtain a full-length cDNA clone from the library. Primers spanning an intron were designed for RTPCR from the sequence of the cDNA. Semi-quantitative RTPCR indicates that HSP101 is expressed constitutively in young leaves at 25 °C and is not induced at moderately higher temperatures (32 °C) even after 5 hours. Induction occurs within 1 hour at 37 °C.