Hd6 , a rice quantitative trait locus involved in photoperiod sensitivity, encodes the α subunit of protein kinase CK2

Abstract

Hd6 is a quantitative trait locus involved in rice photoperiod sensitivity. It was detected in backcross progeny derived from a cross between the japonica variety Nipponbare and the indica variety Kasalath. To isolate a gene at Hd6, we used a large segregating population for the high-resolution and fine-scale mapping of Hd6 and constructed genomic clone contigs around the Hd6 region. Linkage analysis with P1-derived artificial chromosome clone-derived DNA markers delimited Hd6 to a 26.4-kb genomic region. We identified a gene encoding the ␣ subunit of protein kinase CK2 (CK2␣) in this region. The Nipponbare allele of CK2␣ contains a premature stop codon, and the resulting truncated product is undoubtedly nonfunctional. Genetic complementation analysis revealed that the Kasalath allele of CK2␣ increases daysto-heading. Map-based cloning with advanced backcross progeny enabled us to identify a gene underlying a quantitative trait locus even though it exhibited a relatively small effect on the phenotype.

The catalytic subunit of protein kinase CK2 phosphorylates in vitro the movement protein of Tomato mosaic virus

“…A monomeric enzyme has also been reported in some plants (Dobrowolska et al, 1992). To date, cDNA clones for plant CK2 catalytic subunits have been reported in A. thaliana (Mizoguchi et al, 1993), maize (Dobrowolska et al, 1991;Peracchia et al, 1999, Riera et al, 2001, rice (Takahashi et al, 2001) and tobacco (Espunya et al, 1999).…”

“…The deduced protein from the NtCK2a1 cDNA showed a high amino acid identity with the CK2 catalytic subunits from other plants: A. thaliana ATCKA1 (93 %) and ATCKA2 (93 %) (Mizoguchi et al, 1993), Zea mays CK2 a-1 (93 %), CK2 a-2 (93 %) and CK2 a-3 (93 %) (Dobrowolska et al, 1991;Peracchia et al, 1999;Riera et al, 2001), and rice CK2 a (94 %) (Takahashi et al, 2001). It was also homologous to the CK2 subunits from various organisms such as yeast a9 subunit (62 %) (Padmanabha et al, 1990) and human a subunit (76 %) (Lozeman et al, 1990).…”

Rice Root Genetic Architecture: Meta-analysis from a Drought QTL Database

“…These QTL were submitted to a meta-QTL analysis in the same way as the root QTLs. The meta-QTL positions for flowering time were then compared to the physical position of three cloned flowering time QTLs: Hd1 cloned by Yano et al (2000) and Hd3a cloned by Kojima et al (2002), both on chromosome 6, and Hd6 cloned by Takahashi et al (2001) on chromosome 3. These QTLs corresponded to genes Os06g16370 located between base pairs 9,335,361 and 9,337,634 on chromosome 6, Os06g06320 located between bp 2,939,005 and 2,941,453 on chromosome 6 and Os03g10940 located between base pairs 5,595,162 and 5,599,842 on chromosome 3, respectively.…”

Molecular Regulation of Flowering Time in Grasses

“…To induce delayed flowering under LD conditions, Hd6 requires the presence of functional Hd1 alleles and plays a critical role in Hd1 activity. Despite this, Hd6 regulation is not mediated by changes in the circadian clock [37,65]. The rice genome contains two important genes for photoperiodic regulation: Ehd1 and Ghd7, specific to grass species such as rice, maize and sorghum but absent in the Arabidopsis genome [44].…”

“…OsGIGANTEA (OsGI) acts an activator of Heading date1 (Hd1), an ortholog of CO, and controls flowering time by modulating rhythmic flowering under SD [36]. Hd1 encodes a zinc finger type transcriptional activator with the conserved CCT (CO, CO-like, TIMING OF CAB EXPRESSION1 (TOC1)) domain [15,37]. In contrast to Arabidopsis CO, Hd1 promotes Heading date 3a (Hd3a) expression in SD but expression is modified in LD conditions [38,39] where Hd1 function is converted into a repressor.…”