Poster: Seed biology

Abs # 726: Quantitative trait loci (QTL) analysis of hydrotime, high temperatures, and light sensitivity in lettuce seed during germination.

Presenter:	Hayashi, Eiji , ehayashi@csupomona.edu
Authors	Hayashi, Eiji  (A)   Kim, Du-Hyun  (B)   Aoyama, Natsuyo  (A)   Still, David W (A)
Affiliations:	(A): California State Polytechnic University, Pomona (B): National Horticultural Research Institute, South Korea

Seed germination is physiologically and molecularly complex, greatly influenced by environmental factors such as level of dormancy, aging, temperature, light and osmotic stress. In order to elucidate mechanisms by which environmental cues are used to regulate seed germination, we aim to link molecular genetics with the germination response to osmotic and high temperature stress during imbibition using hydrotime and population-based modeling. With a more comprehensive understanding of the molecular and genetic factors, our laboratory seeks to improve germination of lettuce seed to environmental stresses such as high temperature and saline water, both of which decrease final germination or result in secondary dormancy in lettuce. These factors are ubiquitously present in the low desert production areas of Arizona and California. An AFLP linkage map was constructed on an F₂:F₃ population from an intraspecific cross between an iceberg and butter lettuce. Using two different analysis methods, QTLs conferring germination response to high temperature, osmotic stress, and far-red light sensitivity in the mapping population were detected. Although the map is not saturated enough to detect all QTLs associated with those environmental stresses, our data strongly suggests that each characteristic is controlled by two or more QTLs, and that a molecular genetic analysis of these important germination traits is feasible. Given the positive results from the QTL analysis in the F₂:F₃ mapping population, recombinant inbred lines (RILs) were established from the same parent combination. We will show the location and genetic effect of QTLs conferring germination response to high temperature, osmotic stress, and far-red light sensitivity in the F₈ mapping population.