JXB article: Correlation or causality: Genetic disentanglement of wheat traits

20 May 2021 - By: Mareike Jezek

This article highlights the following publication:

Resolving a QTL complex for height, heading, and grain yield on chromosome 3A in bread wheat

Alba Farre Martinez, Clare Lister, Sue Freeman, Jun Ma, Simon Berry, Luzie Wingen, Simon Griffiths

Journal of Experimental Botany, Volume 72, Issue 8, 2 April 2021, Pages 2965–2978,

Correlation or causality: Genetic disentanglement of wheat traits

Wheat domestication was a foundation stone on the pathway from hunter-gatherer to farmer in the history of mankind. We might still be roasting mammoth steaks over open fires if it hadn’t been for the first people in the Middle East to discover the culinary potential of humble looking grasses about 10,000 years ago. Much has happened on a genetic level since then: genomes were duplicated, genes got lost, rearranged, combined and the modern elite bread wheat only vaguely resembles the grass species our ancestors started to cultivate. Yet even after thousands of years of careful selection there is still genetic leeway for increasing the yield potential of modern wheat varieties, a critically important aim to satisfy the ever-growing global food demand.

Pushing the limits of production through genetic gains, however, is not an easy task. Many individual traits such as flowering time, grain number, and grain weight contribute to the overall yield, and potential trade-offs between these traits must be carefully considered when selecting and crossing high yielding lines. For example, a few major effects can be used to optimise ear emergence for UK wheat but some of these are associated with increased crop height, an unwelcome characteristic since tall plants invest relatively less assimilates into grains and fall over more easily in the field. Thus, detailed knowledge about the complex genetics and physiology underlying the overall yield is prerequisite for genome optimization.

In this JXB issue Martinez et al. dissect the contribution of a specific chromosome region present in UK elite winter wheat germplasm to yield formation. It was previously found that this genetic interval affects ear emergence, crop height and grain yield (Griffiths et al 2009,  Griffiths et al 2012, Ma et al 2015), yet the genetic relationship of these effects remained unknown. In contrast to other species such as rice, where these traits have been shown to be regulated by a single gene (Yan et al., 2011), the authors found that heading date and plant height in this case are independent effects with distinct genetic identity in wheat. This finding not only allows for independent trait selection in breeding programmes but also enabled the authors to individually analyse how each of them contribute to grain yield. Near isogenic lines that are genetically different only for specific regions of interest were crossed, genotyped and phenotyped in the field. The results showed that no direct relationship between plant height and grain yield exists. Heading date and grain yield, however, might be pleiotropic effects of the same underlying gene, with Flowering Locus T2 (FT2) being a potential candidate. This assumption will need further confirmation in the future, though. This study not only resolves the genetic relationship of crucial traits but also provides information about their environmental sensitivity to light and temperature. Taken together these findings will assist breeders in developing superior genotypes with increased productivity. 



Griffiths S, Simmonds J, Leverington M, Wang Y, Fish L, Sayers L, Alibert L, Orford S, Wingen L, Herry L. 2009. Meta-QTL analysis of the genetic control of ear emergence in elite European winter wheat germplasm. Theoretical and Applied Genetics 119, 383–395.

Griffiths S, Simmonds J, Leverington M, Wang Y, Fish L, Sayers L, Alibert L, Orford S, Wingen L, Snape J. 2012. Meta-QTL analysis of the genetic control of crop height in elite European winter wheat germplasm. Molecular Breeding 29, 159–171.

Ma J, Wingen LU, Orford S, Fenwick P, Wang J, Griffiths S. 2015. Using the UK reference population Avalon×Cadenza as a platform to compare breeding strategies in elite Western European bread wheat. Molecular Breeding 35, 70.

Yan W-H, Wang P, Chen H-X, Zhou H-J, Li Q-P, Wang C-R, Ding Z-H, Zhang Y-S, Yu S-B, Xing Y-Z. 2011. A major QTL, Ghd8, plays pleiotropic roles in regulating grain productivity, plant height, and heading date in rice. Molecular Plant 4, 319–330.

Mareike Jezek

Author: Mareike Jezek
Category: JXB
Mareike Jezek

Mareike Jezek

Mareike Jezek is the publication Advisor (Institute of Molecular Cell & Systems Biology) of the University of Glasgow and also the Assistant Editor of the Journal of Experimental Botany 

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