A Pseudo-Response Regulator is misexpressed in the photoperiod insensitive Ppd-D1a mutant of wheat (Triticum aestivum L.)

Abstract

Ppd-D1 on chromosome 2D is the major photoperiod response locus in hexaploid wheat (Triticum aestivum). A semi-dominant mutation widely used in the "green revolution" converts wheat from a long day (LD) to a photoperiod insensitive (day neutral) plant, providing adaptation to a broad range of environments. Comparative mapping shows Ppd-D1 to be colinear with the Ppd-H1 gene of barley (Hordeum vulgare) which is a member of the pseudo-response regulator (PRR) gene family. To investigate the relationship between wheat and barley photoperiod genes we isolated homologues of Ppd-H1 from a 'Chinese Spring' wheat BAC library and compared them to sequences from other wheat varieties with known Ppd alleles. Varieties with the photoperiod insensitive Ppd-D1a allele which causes early flowering in short (SD) or LDs had a 2 kb deletion upstream of the coding region. This was associated with misexpression of the 2D PRR gene and expression of the key floral regulator FT in SDs, showing that photoperiod insensitivity is due to activation of a known photoperiod pathway irrespective of day length. Five Ppd-D1 alleles were found but only the 2 kb deletion was associated with photoperiod insensitivity. Photoperiod insensitivity can also be conferred by mutation at a homoeologous locus on chromosome 2B (Ppd-B1). No candidate mutation was found in the 2B PRR gene but polymorphism within the 2B PRR gene cosegregated with the Ppd-B1 locus in a doubled haploid population, suggesting that insensitivity on 2B is due to a mutation outside the sequenced region or to a closely linked gene.

Potential and limits to unravel the genetic architecture and predict the variation of Fusarium head blight resistance in European winter wheat (Triticum aestivum L.)

“…For SSR markers, we excluded those with rates of missing value above 10% and rates of heterozygotes above 5%. All varieties were additionally genotyped for three predefined functional markers, the dwarfing genes Rht-B1, Rht-D1 and the photoperiodism gene Ppd-D1 (Ellis et al, 2002;Beales et al, 2007), which were used for association mapping.…”

Bridging the gap between marker-assisted and genomic selection of heading time and plant height in hybrid wheat

“…Heading time and plant height are important traits for wheat production (Borlaug, 1983;Worland et al, 1998;Distelfeld et al, 2009) and key genes such as Ppd-D1, Rht-B1 and Rht-D1 controlling these traits have been characterized at the molecular level. Ppd-D1 encoding a pseudo-response regulator family member (Turner et al, 2005;Beales et al, 2007) is a major regulator of photoperiod response in wheat with also some effect on plant height (Worland et al, 1998), whereas Rht-B1 and Rht-D1 encoding gibberellin response modulators are major regulators of plant height (Peng et al, 1999). The photoperiod-insensitive allele Ppd-D1a promoting early flowering and short growth as well as the gibberellininsensitive alleles Rht-B1b or Rht-D1b promoting semi-dwarf stature are well represented in wheat adapted to temperate zones (Guo et al, 2010;Le Couviour et al, 2011;Seki et al, 2011;Wilhelm et al, 2013a,b).…”

“…Based on phenotypic data obtained in four environments and genotypic data generated using a wheat 9k SNP array (Akhunov et al, 2009;Cavanagh et al, 2013) and functional markers at gene loci Ppd-D1, Rht-B1 and Rht-D1 (Ellis et al, 2002;Beales et al, 2007) for a large collection of 135 elite winter wheat inbred lines and 1604 F 1 hybrids derived from them, we compared the accuracy of prediction of marker-assisted selection and current genomic selection approaches for the model traits heading time and plant height in a cross-validation approach. For heading time, accuracy was high for marker-assisted selection and low for genomic selection using RR-BLUP and BayesCp, whereas for plant height, accuracy was low for marker-assisted selection as well as for RR-BLUP and BayesCp.…”

Identification of the VERNALIZATION 4 gene reveals the origin of spring growth habit in ancient wheats from South Asia

“…Wheat adaptation to different latitudes and planting dates is mainly associated with natural variation in the photoperiod gene PPD1 that promotes flowering under long days (4)(5)(6) and in the vernalization gene VRN1 that modulates the requirement of long exposures to cold temperatures (vernalization) to induce flowering (7)(8)(9). The photoperiod and vernalization pathways converge at the regulation of FT1 (= VRN3 in wheat) (10), which encodes a mobile protein that travels from leaves to the shoot apical meristem (SAM) (11,12).…”