The Effect of Earliness per se (Eps) Genes on Flowering Time in Bread Wheat

Abstract

Photoperiod (day-length) response, vernalization (response to extended periods of cold) and earliness per se ( Eps ) genes regulate fl owering time in wheat. The vernalization and photoperiod response genes are relatively well studied. However, the role of Eps genes is yet to be fully understood but the current assumption is that Eps genes regulate fl owering independent of vernalization and photoperiod. While some Eps genes have been cloned in both Hordeum vulgare and Triticum monococcum , none has been cloned in Triticum aestivum to date. The use of near isogenic lines (NILs) in both T. monococcum and Triticum aestivum has enabled Eps effects to be studied in more detail and candidate genes have been proposed for Eps effects in both species. Eps loci are reported to be involved in fi ne tuning fl owering time and are also responsible for controlling spikelet number and size hence could be manipulated to increase wheat yield. This mini review summarises our current understanding of Eps and how manipulation of Eps genes can be used in predictive wheat breeding.The world population demands more food, greater diversity of food, a balanced and healthy diet, produced on no more, and preferably less land, while conserving soil, water, and genetic resources. The major problem is that even though wheat yields are increasing (Lopes et al. 2012 ), the percentage increase is below the projected percentage demand with about 0.6 % defi cit projected annually until 2050 (Dixon et al. 2009 ;Rosegrant and Agcaoili 2010 ). The challenge wheat breeders face is to bridge the gap between wheat demand and wheat production. It is therefore vital to direct wheat breeding efforts to the production of higher yielding varieties in order to ensure current and future food security (Reyolds et al. 2012 ). The part of the wheat plant that is important for direct consumption by humans is the grain and its production is dependent on fl owering time. Manipulating fl owering time is one avenue that can be exploited to increase wheat grain yield (Herndl et al. 2008 ; Greenup et al. 2009 ). However, in order to successfully increase grain yield, it is

Uncovering the Genetic Architecture of Fruiting Efficiency in Bread Wheat: A Viable Alternative to Increase Yield Potential

“…Three genetic systems, including vernalization ( Vrn ) response, photoperiod ( Ppd ) sensitivity, and earliness per se, control the developmental phases of wheat (Snape et al, 2001). The major genes controlling photoperiod response in wheat, the Ppd‐1 genes ( Ppd‐A1 , Ppd‐B1 , and Ppd‐D1 ), are located on the homoeologous group 2 chromosomes, and known Vrn genes are located on homoeologous group 5 chromosomes ( Vrn‐A1 , Vrn‐B1 , Vrn‐D1 ), 4B ( Vrn‐B2 ), 4D ( Vrn‐D2 ), 5A ( Vrn‐A2 ), homoeologous group 7 chromosomes ( Vrn‐A3 , Vrn‐B3 , Vrn‐D3 ), and 5D ( Vrn‐D4 ) (Yoshida et al, 2010), although the major earliness per se genes have been fine‐mapped on chromosomes 1A, 1D, 3A, and 7B (Zikhali and Griffiths, 2015). In the current study, three MTAs associated with TA were consistently identified in three genomic regions on chromosomes 2D, 6B, and 7A (Fig.…”

Genetic Architecture of Flowering Phenology in Cereals and Opportunities for Crop Improvement

“…Also known as earliness in the narrow sense, intrinsic earliness, or basic development rate, EPS genes are hypothesized to function as a fine tune adjustment of flowering time (Zikhali and Griffiths, 2015). They are often considered as polygenic and of small genetic effect, and can be detected in both winter and spring wheats.…”

Delimitation of theEarliness per se D1(Eps-D1) flowering gene to a subtelomeric chromosomal deletion in bread wheat (Triticum aestivum)

“…In this way photoperiod and vernaliation genes control adaptation to mega environments. The third class is Eps genes, which control flowering time when both photoperiod and vernalization requirements are met ( Slafer and Rawson, 1994 ), and act in fine tuning flowering time within mega environments ( Zikhali and Griffiths, 2015 ).…”