Structural characterization, expression analysis and evolution of the red/far-red sensing photoreceptor gene, phytochrome C (PHYC), localized on the ‘B’ genome of hexaploid wheat (Triticum aestivum L.)

Abstract

Phytochromes are a family of red/far-red light perceiving photoreceptors. The monocot phytochrome family is represented by three members, PHYA, PHYB and PHYC. We have isolated and characterized the first PHY gene member (TaPHYC) from common wheat, Triticum aestivum var. CPAN1676. It codes for a species of the photoreceptor, phyC, which is known to be light-stable in all plants analyzed so far. A sequence of 7.2 kb has been determined, which includes 3.42 kb of coding region. This is the second full-length PHYC gene sequenced from a monocot (first was from rice). TaPHYC gene shares structural similarities with the rice PHYC containing four exons and three introns in the coding region. The 5' UTR is 1.0-kb-long and harbors an upstream open reading frame (URF) encoding 28 aa. Southern blot analysis of TaPHYC indicates that it represents single locus in the wheat genome, although the possibility of additional loci cannot be completely ruled out. Chromosomal localization using nullisomic-tetrasomic lines of Triticum aestivum var. Chinese Spring places TaPHYC on chromosome 4B. PHYC represents a constitutively expressed gene in all the organs tested and under light/dark conditions. However, PHYC was found to be developmentally regulated showing maximal expression in 3-day-old dark-grown seedlings, which declined thereafter. In silico analysis has also been done to compare TaPHYC gene with the partial sequences known from other wheat species and cultivars. The presence of a topoisomerase gene immediately downstream of the PHYC gene, both in rice and wheat genomes, presents yet another example of synteny in cereals and its possible significance has been discussed.

Phytochrome B enhances plant growth, biomass and grain yield in field-grown maize

“…Monocots possess three phy gene clades called PHYA, PHYB and PHYC (Mathews and Sharrock, 1997;Kulshreshtha et al, 2005). In maize, these genes are duplicated, presenting PHYA1, PHYB1 and PHYC1 genes on chromosome 1, PHYA2 and PHYC2 on chromosome 5S, and PHYB2 on chromosome 9L (Sheehan et al, 2004).…”

Low red/far-red ratios delay spike and stem growth in wheat

“…The initiation of tiller death in wheat crops has been related to a threshold R/FR ratio (Sparkes et al , 2006), and a low R/FR ratio also has a role in determining rooting traits that affect the anchorage capacity of wheat plants and favour lodging (Sparkes and King, 2008). The phytochrome gene family contains three members— PHYA , PHYB , and PHYC —in grasses (Mathews and Sharrock, 1996; Kulshreshtha et al , 2005). Based on observations in maize (Sheehan et al , 2007), sorghum (Childs et al , 1997), rice (Takano et al , 2005), and barley (Hanumappa et al , 1999), the responses to the R/FR ratio appear to be mediated mainly by phytochrome B.…”

A Dominant Mutation in the Light-Oxygen and Voltage2 Domain Vicinity Impairs Phototropin1 Signaling in Tomato

“…The tomato seedling cDNA library in l ZAP II (Stratagene) was screened for putative PHOT2 with radiolabeled EST clone BG 126772 using conditions described by Kulshreshtha et al (2005). Subsequent sequencing was performed using commercially available T3 and T7, with primers resulting in eight individual truncated clones having approximately 70% similarity with Arabidopsis (Arabidopsis thaliana) PHOT2 cDNA.…”