Authors: H Nakagawa J Yamagishi N Miyamoto M Motoyama M Yano K Nemoto
Publish Date: 2005/01/26
Volume: 110, Issue: 4, Pages: 778-786
Abstract
In this study we have attempted to quantify the thermal and photoperiodical responses of rice Oryza sativa L flowering time QTLs jointly by a ‘dateofplanting’ field experiment of a mapping population and a ‘phenological model’ analysis that separately parameterizes the two responses based on daily temperature daily photoperiod and flowering date For this purpose the ‘threestage Beta model’ which parameterizes the sensitivity to temperature parameter α the sensitivity to photoperiod parameter β and earliness under optimal conditions 10 h photoperiod at 30°C parameter G was applied to ‘Nipponbare’ × ‘Kasalath’ backcross inbred lines that were transplanted on five dates QTLs for the β value were detected in the four known flowering time QTL Hd1 Hd2 Hd6 and Hd8 regions while QTLs for the G value were detected only in the Hd1 and Hd2 regions This result was consistent with previous reports on nearisogenic lines NILs of Hd1 Hd2 and Hd6 where these loci were involved in photoperiod sensitivity and where Hd1 and Hd2 conferred altered flowering under both 10 and 14 h photoperiods while Hd6 action was only affected by the 14 h photoperiod Hd8 was shown to control photoperiod sensitivity for the first time Interestingly Hd1 and Hd2 were associated with a QTL for the α value which might support the previous hypothesis that the process of photoinduction depends on temperature These results demonstrate that our approach can effectively quantify environmental responses of flowering time QTLs without controlled environments or NILsWe are grateful to Dr Xinyou Yin Wageningen University and Research Centre for valuable advice on modelQTL analysis Dr Rebecca C Laza International Rice Research Institute for critically reviewing the manuscript Dr Shoichi Suzuki Ishikawa Agricultural College for suggestions on the genetic analysis and Mr Noboru Washizu Mr Kenichiro Ichikawa Ms Shizue Nakada and Mr Hiroshi Kimura The University of Tokyo for their technical assistance in field management This work was supported by a GrantinAid for Scientific Research No13556004 and No15380013 to KN from the Ministry of Education Science Sports and Culture Japan
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