Winter sugarbeet: Identification of a mutant parental line resistant to post-winter bolting

Authors: Eujayl, Imad; Faler, Joyce; Strausbaugh, Carl

Submitted to: Journal of Sugar Beet Research
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2019
Publication Date: 6/1/2019
Citation: Eujayl, I.A., Faler, J.C., Strausbaugh, C.A. 2019. Winter sugarbeet: Identification of a mutant parental line resistant to post-winter bolting. Journal of Sugar Beet Research. 56(1&2):80.

Interpretive Summary: Planting sugar beet in the fall can provide a new winter crop or extend the growing season in temperate climates. The genetics of sugar beet resistance to post-winter bolting (flowering) is highly heritable. This study identified a mutant line; namely KEMS12-17FP that was selected from KEMS-12; PI672570. We identified four DNA markers that are linked to the genes controlling the post-winter non-bolting trait. KEMS12-17FP was planted in the fall of 2015 at the USDA-ARS research station in Kimberly, Idaho (42.5o N 114.4o W). In the spring of 2016, individual plants homozygous for the four DNA-markers didn’t bolt. The selected individuals were artificially re-vernalized for 120 days that resulted in normal seed setting. When planted in the fall of 2017, 82% of the mutant didn’t bolt/flower. Roots of non-bolting plants were manually harvested and sampled for sucrose content. This line was used as female-parent to produce hybrids (F1). Hybrids were planted in the fall of 2017, showed bolters and non-bolters in the spring of 2018. KEMS12-FP17 is a parental line that is suitable for introducing the non-bolting resistance trait into commercial parental genetic backgrounds to produce non-bolting frost tolerant cultivars.

Technical Abstract: The biennial nature of the sugarbeet plant leverages extended vegetative growth that is associated with increased sugar yield under favorable climate. Planting sugar beet in the fall/autumn can provide a new winter crop or extend the growing season in temperate climates. The genetics of sugar beet resistance to post-winter bolting is highly heritable (h2=0.85) and under control of a quantitative trait locus (QTL) in chromosome IX. Specifically, BR1 is the major monogenic inheritance indicator of the locus, but with incomplete genetic-penetrance. In this study we identified a mutant line; namely KEMS12-17FP (selected from KEMS-12; PI672570) that carries four DNA markers within this QTL. KEMS12-17FP was planted in the fall of 2015 at the USDA-ARS research station in Kimberly, Idaho (42.5o N 114.4o W). In the spring of 2016, individuals homozygous for the four DNA-markers didn’t bolt. The selected individuals were artificially re-vernalized for 120 days that resulted in normal seed setting. When planted in the fall of 2017, the KEMS12-17FP plants had 82% post-winter bolting resistance since the line was not homozygous for this trait. Roots from non-bolting individuals were manually harvested and sampled for sucrose content. The average sucrose content of 15.5% of this pre-breeding line is normal. This line was used as female-parent to produce F1, while the male parents (KPS19, KPS24 and KPS25) were heterozygous and their post-winter bolting resistance was unknown. The F1 individuals were planted in the fall of 2017 had both post-winter bolting resistant individuals and individuals that bolted after winter. KEMS12-FP17 is a parental line that is suitable for introducing the non-bolting resistance trait into commercial parental genetic backgrounds to produce non-bolting frost tolerant cultivars.