|Holland, Jim - Jim|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/30/2001
Publication Date: 7/10/2002
Citation: Interpretive Summary: Small grain crops respond to day length (photoperiod) and vernalization (cold weather that occurs during germination or early development) by adjusting their flowering time. Responses vary among varieties, however, because different responses to these environmental cues correspond to adaptation to different ecogeographic regions. Major genes for both photoperiod and vernalization responses have been mapped in wheat and barley, but not in oat. In this study, we mapped gene regions that contribute quantitatively to the photoperiod and vernalization responses in oat. Vernalization and longer day lengths shortened time to flowering, and we identified several gene regions that mediate this response. These regions were also associated with chromosomal rearrangements, suggesting that chromosomal rearrangements that occur near these genes are maintained throughout evolution because they hinder gene flow between plants of the same species that are adapted to different regions.
Technical Abstract: Oat genotypes vary for photoperiod and vernalization responses. Vernalization often promotes earlier flowering in fall-sown but not spring- sown cultivars. Longer photoperiods also promote earlier flowering, and the response to longer photoperiods tends to be greater in cultivars from higher latitudes. To investigates the genetic basis of photoperiod and vernalization responses in oat, QTL was mapped for flowering time under four combinations of photoperiod and vernalization treatments in the Ogle x TAM 0-301 mapping population in growth chambers. QTL was also mapped for flowering time in early springs and late spring field plantings to determined the genetic basis of response to planting dates in oat. Three major flowering time QTL (on linkage groups OT8, OT31, and OT32) were detected in most conditions. QTL with smaller effects on flowering were less consistently observed among treatments. Both vernalization-sensitive and insensitive QTL were discovered. Longer photoperiod or vernalization alone tended to decrease the effects of flowering time QTL. Applied together, longer photoperiod and vernalization alone tended to decrease the effects of flowering time QTL. Applied together, longer photoperiod and vernalization interacted synergistically, often on the same genomic regions. Earlier spring planting conferred an attenuated vernalization treatment on seeds. The major flowering time QTL mapped in this study matched those mapped previously in the Kanota x Ogle oat mapping population. Between these two studies, we found a concordance of flowering time QTL, segregation distortion, and complex genetic linkages. These effects may all be related to chromosomal rearrangements in hexaploid oat.