SUGAR BEET GERMINATION: PHENOTYPIC SELECTION AND MOLECULAR PROFILING TO IDENTIFY GENES INVOLVED IN ABIOTIC STRESS RESPONSE

Emergence and stand establishment are critical concerns of sugar beet growers worldwide, and abiotic stresses potentially limit the types of varieties that can be grown productively. This project seeks to develop information that will be useful in selecting and breeding sugar beet for enhanced emergence in saline conditions. We developed a simple bioassay using seeds submerged in salt water to screen 147 germplasm lines for their ability to germinate in 150 mM NaCl as compared with 0.3% H₂O₂, and used the ratio as a predictor of field emergence potential (FEP). Simultaneously, we surveyed gene expression during salt germination in order to identify potential molecular breeding targets. Expressed Sequence Tags (ESTs) were obtained from 3,119 transcripts of 4-day old seedlings germinated in saline and H₂O₂ solutions. Results suggest that 1-carbon metabolism is an important process in stress germinating seedlings. Results also indicated that germplasm differs in germination under salt stress, and in at least one germplasm, differential gene expression is observed. Results from the salt germination assay appear to be consistent with tolerance at the whole plant level, at least for some tested lines. This information will allow subsequent breeding and physiological studies on sugar beet salt tolerance, for instance in identifying highly salt tolerant sugarbeet germplasm that could be used to help remediate saline soils.