Heading date gene, dth3 controlled late flowering in O. Glaberrima Steud. by down-regulating Ehd1

Abstract

Heading date in rice is an important agronomic trait controlled by several genes. In this study, flowering time of variety Dianjingyou 1 (DJY1) was earlier than a near-isogenic line (named NIL) carried chromosome segment from African rice on chromosome 3S, when grown in both long-day (LD) and short-day (SD) conditions. By analyzing a large F2 population from NIL × DJY1, the locus DTH3 (QTL for days to heading on chromosome 3) controlling early heading date in DJY1 was fine mapped to a 64-kb segment which contained only one annotated gene, a MIKC-type MADS-box protein. We detected a 6-bp deletion and a single base substitution in the C-domain by sequencing DTH3 in DJY1 compared with dth3 in NIL, and overexpression of DTH3 caused early flowering in callus. Quantitative real-time PCR revealed that the transcript level of dth3 in NIL was lower than that DTH3 in DJY1 in both LD and SD conditions. The Early heading date 1 (Ehd1) which promotes the RFT1, was up-regulated by DTH3 in both LD and SD conditions. Based on Indel and dCAPs marker analysis, the dth3 allele was only present in African rice accessions. A phylogenetic analysis based on microsatellite genotyping suggested that African rice had a close genetic relationship to O. rufipogon and O. latifolia, and was similar to japonica cultivars. DTH3 affected flowering time and had no significant effect on the main agronomic traits.

Development and Evaluation of Chromosome Segment Substitution Lines Carrying Overlapping Chromosome Segments of the Whole Wild Rice Genome

“…Tan et al (2008) cloned the PROG1 gene from common wild rice, and prog1 variants identified in O. sativa disrupt prog1 function and inactivate prog1 expression, leading to erect growth, greater grain number and higher grain yield in cultivated rice. At the same time, the flowering time QTL dth3 , was detected from wild rice species (Bian et al, 2011), and the seed dormancy QTL was also isolated in the genetic populations derived from wild rice species (Gu et al, 2004). …”

Cloning of quantitative trait genes from rice reveals conservation and divergence of photoperiod flowering pathways in Arabidopsis and rice

“…DTH3 up-regulates Ehd1 and RFT1 under both SD and LD conditions and thereby promotes flowering (Bian et al, 2011) (Figure 1). At this QTL, there is functional allelic variation between O. sativa and O. glaberrima , but probably not among O. sativa cultivars.…”

Two Novel QTLs for Heading Date Are Identified Using a Set of Chromosome Segment Substitution Lines in Rice (Oryza sativa L.)

“…S3A). It was reported that the expression level of dth3 in the near isogenic line was lower than that of DTH3 in DJY1, and overexpression of DTH3 caused early flowering (Bian et al, 2011). Probably the polymorphisms in promoter region can cause different gene expression level and resulted functional distinction.…”

“…QHD2 was mapped to the interval RM497-R240, which contained the recently cloned heading date gene DTH2 (Wu et al, 2013). QHD3 was mapped to the region flanked by markers RM36 and RM232, where DTH3 is located (Bian et al, 2011). No cloned heading date genes were reported in the regions harboring the remaining seven QTLs.…”