Molecular Regulation of Flowering Time in Grasses

Abstract

Flowering time is a key target trait for extending the vegetative phase to increase biomass in bioenergy crops such as perennial C 4 grasses. Molecular genetic studies allow the identification of genes involved in the control of flowering in different species. Some regulatory factors of the Arabidopsis pathway are conserved in other plant species such as grasses. However, differences in the function of particular genes confer specific responses to flowering. One of the major pathways is photoperiod regulation, based on the interaction of the circadian clock and environmental light signals.Depending on their requirements for day-length plants can be classified as long-day (LD), short-day (SD), and day-neutral. The CONSTANS (CO) and Heading Date 1 (Hd1), orthologos genes, are central regulators in the flowering of Arabidopsis and rice, LD and SD plants, respectively. Additionally, Early heading date 1 (Ehd1) induces the expression of Heading date 3a (Hd3a), conferring SD promotion and controls Rice Flowering Locus T 1 (RFT1) in LD conditions, independently of Hd1. Nevertheless, the mechanisms promoting flowering in perennial bioenergy crops are poorly understood. Recent progress on the regulatory network of important gramineous crops and components involved in flowering control will be discussed.

Transcriptional Analysis of Flowering Time in Switchgrass

“…Flowering in switchgrass is influenced by many factors, both endogenous and exogenous. Some components of the photoperiod and autonomous pathways have been identified in switchgrass [33]; however, investigations in sorghum, another high biomass crop, have yielded more pieces of the flowering pathway in grasses. Three well-characterized maturity loci in sorghum, Ma1, Ma3, and Ma6, harbor floral repressors that confer photoperiod sensitivity [34].…”

Dynamic effects of interacting genes underlying rice flowering-time phenotypic plasticity and global adaptation

“…Heading date 1 (Hd1), a homolog of CONSTANS from Arabidopsis, is a central regulator of flowering time in rice, a facultative short day-length (SD) plant (Yano et al 2000). Hd1 promotes Heading date 3a (Hd3a; a florigen-coding gene) expression in SD and suppresses the expression of Hd3a in long day-length (LD) conditions (Hayama et al 2003;Tamaki et al 2007;Nuñez and Yamada 2017). OsGIGANTEA (OsGI) acts as an activator of Hd1 under SD.…”

Improving the Yield and Nutritional Quality of Forage Crops

“…As biomass yield is the main target for forage crop improvement, more rapidly growing cultivars can be targeted for breeding. Studies have consequently focussed on heading date ( Fe et al, 2015 ) and flowering time regulation ( Skøt et al, 2011 ; Shinozuka et al, 2012 ) in Lolium by developing Genomic Prediction models and QTL mapping as described previously ( Nuñez and Yamada, 2017 ). Manipulating genes involved in delayed senescence has been targeted for increasing biomass yields.…”