Abstract
BackgroundFlowering time, which is often associated with the length of the growth period in rice, determines the adaptability of a plant to various environments. However, little is known about how flowering-time genes affect panicle development and yield formation potential in rice after inducing the transition from vegetative growth to reproductive growth.ResultsTo explore the relationship between floral induction and yield formation and the molecular mechanism of panicle development in rice, a novel mutant, ghd10, was identified from japonica variety Wuyunjing 7 plants subjected to ethyl methane sulfonate (EMS) treatment. The ghd10 mutant exhibited delayed flowering time, tall stalks and increased panicle length and primary branch number. Map-based cloning revealed that Ghd10 encodes a transcription factor with Cys-2/His-2-type zinc finger motifs. Ghd10 is orthologous to INDETERMINATE1 (ID1), which promotes flowering in maize (Zea mays) and is identical to the previously cloned genes Rice Indeterminate1 (RID1), Early heading date2 (Ehd2) and OsId1. Transient expression analysis of the Ghd10-GFP fusion protein in tobacco mesophyll cells showed that this protein is expressed in the nucleus. Ghd10 mRNA accumulated most abundantly in developing leaves and panicle structures, but rarely in roots. Expression analysis revealed that the expression levels of Ehd1, Hd1, RFT1, Hd3a and OsMADS15 decreased dramatically under both short-day and long-day conditions in ghd10.ConclusionThese results indicate that Ghd10, which encodes a promoter of flowering, influences plant height and panicle development by regulating the expression levels of some flowering-related genes, such as Ehd1, Hd1, OsMADS15 and others. The ghd10 allele is a useful resource for improvement of panicle traits in rice grown in tropical and low-latitude areas.Electronic supplementary materialThe online version of this article (doi:10.1186/1939-8433-6-24) contains supplementary material, which is available to authorized users.
Highlights
Flowering time, which is often associated with the length of the growth period in rice, determines the adaptability of a plant to various environments
Map-based cloning revealed that Ghd10 encodes a transcription factor with Cys-2/His2-type zinc finger motifs that is orthologous to INDETERMINATE1 (ID1), which promotes flowering in maize (Zea mays) and was previously identified as Rice Indeterminate1 (RID1), Early Heading Date2 (Ehd2) and OsId1 in rice
The ghd10 gain-of-function allele in panicle development The ghd10 mutant was obtained from japonica cultivar Wuyunjing 7 (WYJ7) rice plants subjected to ethyl methane sulfonate (EMS) treatment
Summary
Flowering time, which is often associated with the length of the growth period in rice, determines the adaptability of a plant to various environments. The response to the length of day (LOD) of a rice plant (namely, photoperiod sensitivity [PS]), its temperature sensitivity (TS) and basic vegetative growth (BVG) determine the heading date of the plant The interaction between these factors is thought to determine adaptability of a rice variety (Lee and An 2007). Hd6, involving in rice photoperiod sensitivity, encodes the α-subunit of protein kinase CK2α (CK2α) to increase the days-toheading (Takahashi et al 2001) Another flowering-related gene, Hd3a acts as a floral activator under SD conditions and is regulated by Hd1 (Kojima et al 2002). Previous studies found that Ghd and Ghd8/DTH8 control multiple-traits of flowering time, plant height and grain numbers per panicle simultaneously (Wei et al 2010; Xue et al 2008; Yan et al 2011)
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