|Mcgrath, J Mitchell - Mitch|
|De Los Reyes, Benildo|
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2007
Publication Date: 1/15/2008
Citation: McGrath, J.M., Elawady, A., El-Khishin, D., Naegele, R.P., Carr, K.M., De Los Reyes, B. 2008. Sugar Beet Germination: Phenotypic Selection and Molecular Profiling to Identify Genes Involved in Abiotic Stress Response. Acta Horticulturae. 782:35-50.
Interpretive Summary: Sugar beets are most vulnerable to stress and disease during the first 10 weeks after planting. In some cases, the soil conditions may not be optimal for emergence. A germination test using salt water was used to simulate poor soils to screen for sugar beets and wild beets for enhanced ability to germinate under such stressful conditions. Differences in the ability to germinate in salt water were shown, and more of the wild beet accessions tested showed this ability, suggesting that novel genetic combinations for enhanced emergence might be found among these materials. The genes responsible for the ability to germinate in salt water were investigated in order to deduce potential biochemical mechanisms for enhanced germination. The response to stress appeared rather complex. However a few targets of opportunity could be identified, such as those processes that are needed for energy and to supply carbon atoms for growth and development. Scientists and breeders now have germplasm and tools to improve selection for enhanced germplasm during abiotic stress.
Technical Abstract: Emergence and stand establish 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 hydrogen peroxide solutions, and results suggest that 1-carbon metabolism is an important process in stress germinating seedlings. Results 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.