Location: Crop Improvement and Protection ResearchTitle: Identifying QTL for the control of flowering time under multiple environments in lettuce
|ROSENTAL, L - FORMER ARS EMPLOYEE|
|YOU, Y - CALIFORNIA POLYTECHNIC STATE UNIVERSITY|
|STILL, D - CALIFORNIA POLYTECHNIC STATE UNIVERSITY|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/21/2019
Publication Date: 5/27/2019
Citation: Rosental, L., You, Y., Hayes, R.J., Still, D., Simko, I. 2019. Identifying QTL for the control of flowering time under multiple environments in lettuce. Israeli Society of Field and Vegetable Crops Conference, May 27, 2019, Rehovot, Israel.
Technical Abstract: Premature bolting and early flowering is an economic problem, exacerbated by heat conditions, where many varieties will bolt before harvest, producing bitter latex and rendering the product unsalable. In order to better understand the genetic factors controlling the environmental response to this trait a RIL population was studied in six independent field studies in three different locations. The parents for the population are Salinas, a slow bolting iceberg type lettuce, and PI 251246, a fast bolting lettuce grown for oil in its seeds. Environmental conditions during the field studies ranged from maximum temperate of 32.2°C to 42°C. Based on GBS genotyping of the 161 RILs we constructed a linkage map of 753 markers, with good coverage of the nine lettuce chromosomes. QTL mapping revealed four significant QTLs for bolting and flowering, with different effects for the two traits. All four QTL have strong environmental interactions and have a significant effect on the traits only under some of the conditions tested. A QTL on chromosome 2 had a higher effect on bolting and flowering in warmer experiments, while the large QTL on chromosome 7 had a stronger effect on bolting during cooler long day conditions. Another QTL on chromosome 7 had a smaller though significant effect on both bolting and flowering. The QTL on chromosome 6 had a high effect on bolting time under five conditions, but a lower effect on flowering. The three highest LOD QTLs were investigated further by fine mapping and gene expression studies. We found lettuce FT gene to be a likely candidate for QTL 2.1 and two known flowering time genes, COL-9 and PhyC to be likely candidates in QTL 7.2. The information revealed in this work is being used with marker assisted selection to improve lettuce breeding lines for resistance to premature bolting.