Comparative Genomics and Functional Characterisation of the GIGANTEA Gene from the Temperate Forage Perennial Ryegrass Lolium perenne

Abstract

Lolium perenne (ryegrass) is a perennial forage grass of worldwide importance. It is a temperate climate grass and flowering is induced by long day photoperiods. The agronomic productivity of ryegrass is strongly influenced by flowering time, but less is known about ryegrass flowering time regulators in other temperate Poaceae like wheat, barley and the model grass Brachypodium. The GIGANTEA (GI) gene was first identified in Arabidopsis and is an important regulator of photoperiodic flowering in angiosperms. GI usually exists as a conserved, single-copy gene. However, recently, genome sequencing has revealed that some plants, including the tropical grass maize, carry more than one full-length copy of GI. Here we describe the isolation and characterisation of the ryegrass L. perenne GIGANTEA gene (LpGI) gene. Comparative genomic analysis indicates that LpGI gene structure is very well conserved overall with GI genes from monocots and eudicots. LpGI protein clusters with GI proteins from other temperate grasses and is most closely related to the GI protein from meadow fescue. Genetic mapping locates LpGI to a chromosomal region that is syntenic with rice and Brachypodium GI. Our functional characterisation shows that LpGI shows a diurnal pattern of expression, continues to oscillate under constant light and adjusts its phase in response to changes in day length as seen in other plants. Constitutive expression of LpGI completely rescues the Arabidopsis gigantea-3 allele (gi-3) mutation, confirming that the isolated ryegrass gene is fully functional. Taken together, it is highly likely that LpGI is orthologous to Arabidopsis GI and involved in photoperiodic flowering time control in ryegrass.

Fluorescence chromosome banding and FISH mapping in perennial ryegrass, Lolium perenne L.

“…Indeed, as noted by Kopecky and Studer [1], only one of the seven chromosomes had so far been discriminated. GIGANTEA ( LpGI ) has been mapped to LG3 of L. perenne [40]. Here, this single copy gene has been precisely assigned through FISH mapping to a cytogenetic band on the short arm of chromosome 2 (Fig.…”

Expression of sugarcane genes associated with perception of photoperiod and floral induction reveals cycling over a 24-hour period

“…In rice and soybean, grown under floral induction conditions, the peak expression of GI was maintained at the transition from the light to dark period, but this is now occurring earlier in the 24-h cycle (expression has contracted with the short daylength), and in rice, expression was increased by~25% (Filichkin et al 2011;Hori et al 2013;Li et al 2013). Under SD conditions, expression of LpGI in rye grass occurred earlier in the 24-h period and expression was reduced (Gagic et al 2015). Further analysis is required to determine if ShGI expression alters similarly to rice, soybean and rye grass during floral inductive conditions.…”

The Importance of the Circadian Clock in Regulating Plant Metabolism

“…Manipulating the circadian clock in crop plants may help to overcome problems of climate change and food deficiency. However, translating molecular mechanisms of model plants to crop plants is difficult because many crop plants of agricultural significance have experienced diverse evolution ( Table 1 ) [ 51 , 52 , 53 , 54 , 55 ].…”