Abstract:

Flowering time is one of the most important agronomic traits and determines the regional adaptability and yield in rice. Artificial selection makes rice expand from short-day to long-day and low-latitude to high-latitude,thus rice has gradually evolved a flowering regulation mechanism adapted to long-day. Currently,the mining of rice long-day flowering genes is still very limited although some flowering genes,such as SDG724,RFT1,EHD4,and DTH2 that affect rice long-day trait,have been identified. In this study,a batch of mutant materials with significant differences in flowering period under long-day were obtained by screening the rice mutant library. One of these mutants,lfm1（late-flowering mutant1）,delayed flowering under long-day conditions and was normal under short-day conditions. Through map-based cloning,the Lfm1 gene was initially located near the telomere of chromosome 8. Lfm1 was located near the telomere of chromosome 8. Fine mapping revealed that the Lfm1 gene was located between the molecular markers 8-0.269 and 8-0.283. There were 3 candidated genes in this region of 12 kb. Through sequencing analysis,9 bp deletion at position 2 800 of the sixth exon of the LOC_Os08g01420 was found in lfm1,and lfm1 was an allele of ehd3. It is worth of mentioning that under moderate light conditions（~12 h/12 h）,the mutant lfm1 showed an increase in the number of grains per panicle and a slightly longer growth period,thus it can be used in production potentially. The cloning of Lfm1 gene provides an important gene resource for breeding rice materials adapted to different ecological regions.

Key words: rice（Oryza sativa L.）, long-day, heading date, map-based cloning