Summary
Flowering is regulated by genes that respond to changing daylengths and temperature, which have been well studied using controlled conditions; however, the molecular processes underpinning ...flowering in nature remain poorly understood.
Here, we investigate the genetic pathways that coordinate flowering and inflorescence development of wheat (Triticum aestivum) as daylengths extend naturally in the field, using lines that contain variant alleles for the key photoperiod gene, Photoperiod‐1 (Ppd‐1).
We found flowering involves a stepwise increase in the expression of FLOWERING LOCUS T1 (FT1), which initiates under day‐neutral conditions of early spring. The incremental rise in FT1 expression is overridden in plants that contain a photoperiod‐insensitive allele of Ppd‐1, which hastens the completion of spikelet development and accelerates flowering time. The accelerated inflorescence development of photoperiod‐insensitive lines is promoted by advanced seasonal expression of floral meristem identity genes. The completion of spikelet formation is promoted by FLOWERING LOCUS T2, which regulates spikelet number and is activated by Ppd‐1.
In wheat, flowering under natural photoperiods is regulated by stepwise increases in the expression of FT1, which responds dynamically to extending daylengths to promote early inflorescence development. This research provides a strong foundation to improve yield potential by fine‐tuning the photoperiod‐dependent control of inflorescence development.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The ability to flower without strict daylength constraints has helped spread cultivation of crop plants to new locations. The generation of daylength-insensitive common bean accessions in central and ...South America involved the repeated selection of mutant alleles for a key transcription factor that suppresses long-day flowering.
The ability to flower without strict daylength constraints has helped spread cultivation of crop plants to new locations. The generation of daylength-insensitive common bean accessions in Central and South America involved the repeated selection of mutant alleles for a key transcription factor that suppresses long-day flowering.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Modifications of inflorescence architecture have been crucial for the successful domestication of wheat and barley, which are central members of the Triticeae tribe that provide essential grains for ...the human diet. Investigation of the genes and alleles that underpin domestication‐related traits has provided valuable insights into the molecular regulation of inflorescence development of the Triticeae, and further investigation of modified forms of architecture are proving to be equally fruitful. The identified genes are involved in diverse biological processes, including transcriptional regulation, hormone biosynthesis and metabolism, post‐transcriptional and post‐translational regulation, which alter inflorescence architecture by modifying the development and fertility of lateral organs, called spikelets and florets. Recent advances in sequencing capabilities and the generation of mutant populations are accelerating the identification of genes that influence inflorescence development, which is important given that genetic variation for this trait promises to be a valuable resource for optimizing grain production. This review assesses recent advances in our understanding of the genes controlling inflorescence development in wheat and barley, with the aim of highlighting the importance of improvements in developmental biology for optimizing the agronomic performance of staple crop plants.
This review summarizes the recent advances on the genetic regulation of inflorescence architecture in the Triticeae tribe, including the staple crops of wheat and barley. We focus on the key domestication related traits, and recent studies that have used modified forms of inflorescence architecture to identify genes regulating spikelet and floret development.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Regulation of plant height and stem elongation has contributed significantly to improvement of cereal productivity by reducing lodging and improving distribution of assimilates to the inflorescence ...and grain. In wheat, genetic control of height has been largely contributed by the Reduced height-1 alleles that confer gibberellin insensitivity; the beneficial effects of these alleles are associated with less favourable effects involving seedling emergence, grain quality, and inflorescence architecture that have driven new research investigating genetic variation of stem growth. Here, we show that TEOSINTE BRANCHED1 (TB1) regulates height of wheat, with TB1 being expressed at low levels in nodes of the main culm prior to elongation, and increased dosage of TB1 restricting elongation of stem internodes. The effect of TB1 on stem growth is not accompanied by poor seedling emergence, as transgenic lines with increased activity of TB1 form longer coleoptiles than null transgenic controls. Analysis of height in a multiparent mapping population also showed that allelic variation for TB1 on the B genome influences height, with plants containing the variant TB-B1b allele being taller than those with the wild-type TB-B1a allele. Our results show that TB1 restricts height and stem elongation in wheat, suggesting that variant alleles that alter the expression or function of TB1 could be used as a new source of genetic diversity for optimizing architecture of wheat in breeding programmes.
Abstract
The increasing demand for global food security in the face of a warming climate is leading researchers to investigate the physiological and molecular responses of cereals to rising ambient ...temperatures. Wheat and barley are temperate cereals whose yields are adversely affected by high ambient temperatures, with each 1 °C increase above optimum temperatures reducing productivity by 5–6%. Reproductive development is vulnerable to high-temperature stress, which reduces yields by decreasing grain number and/or size and weight. In recent years, analysis of early inflorescence development and genetic pathways that control the vegetative to floral transition have elucidated molecular processes that respond to rising temperatures, including those involved in the vernalization- and photoperiod-dependent control of flowering. In comparison, our understanding of genes that underpin thermal responses during later developmental stages remains poor, thus highlighting a key area for future research. This review outlines the responses of developmental genes to warmer conditions and summarizes our knowledge of the reproductive traits of wheat and barley influenced by high temperatures. We explore ways in which recent advances in wheat and barley research capabilities could help identify genes that underpin responses to rising temperatures, and how improved knowledge of the genetic regulation of reproduction and plant architecture could be used to develop thermally resilient cultivars.
We outline recent advancements in our understanding of the reproductive developmental traits and genetic pathways underpinning responses of wheat and barley to high ambient temperatures, and propose new strategies for developing thermotolerant cultivars.
Agriculture is challenged globally from a variety of fronts, including a steady increase in world population, changes in climate and a requirement to reduce fertiliser inputs. In the production of ...crops that are able to overcome these challenges, developmental biology can play a crucial role. The process of domesticating wild progenitors into edible crops is closely linked to modification of developmental processes, and the steps that are needed to face the current challenges will equally require developmental modifications. In this Spotlight, we describe the achievements by developmental biologists in identifying the genes responsible for domestication of some of the most important crops, and highlight that developmental biology is in a unique position to remain centre stage in improving crop performance to meet current and future demands. We propose that the explosive technological advances in sequencing, genome editing and advanced data processing provide an excellent opportunity for researchers to combine scientific disciplines and realise the continued potential of plants as the primary food source for generations to come.
Flowering is a vital process in a plant's lifecycle and variation for flowering-time has helped cereals adapt to diverse environments. Much cereal research has focused on understanding how flowering ...signals, or florigens, regulate the floral transition and timing of ear emergence. However, flowering genes also perform an enduring role during inflorescence development, with genotypes that elicit a weaker flowering signal producing more elaborately branched inflorescences with extra floret-bearing spikelets. While this outcome indicates that variable expression of flowering genes could boost yield potential, further analysis has shown that dampened florigen levels can compromise fertility, negating the benefit of extra grain-producing sites. Here, we discuss ways that florigens contribute to early and late inflorescence development, including their influence on branch/spikelet architecture and fertility. We propose that a deeper understanding of the role for florigens during inflorescence development could be used to balance the effects of florigens throughout flowering to improve productivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A defining characteristic of grasses, including major cereal crops, is the way in which flowers are arranged on an inflorescence. A new study finds that regulation of hormone levels during ...development is crucial for determining the arrangement of flowers on a barley inflorescence, opening new doors for increasing grain yield.
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IJS, NUK, SBMB, UL, UM, UPUK
Crop populations derived from experimental crosses enable the genetic dissection of complex traits and support modern plant breeding. Among these, multi-parent populations now play a central role. By ...mixing and recombining the genomes of multiple founders, multi-parent populations combine many commonly sought beneficial properties of genetic mapping populations. For example, they have high power and resolution for mapping quantitative trait loci, high genetic diversity and minimal population structure. Many multi-parent populations have been constructed in crop species, and their inbred germplasm and associated phenotypic and genotypic data serve as enduring resources. Their utility has grown from being a tool for mapping quantitative trait loci to a means of providing germplasm for breeding programmes. Genomics approaches, including de novo genome assemblies and gene annotations for the population founders, have allowed the imputation of rich sequence information into the descendent population, expanding the breadth of research and breeding applications of multi-parent populations. Here, we report recent successes from crop multi-parent populations in crops. We also propose an ideal genotypic, phenotypic and germplasm 'package' that multi-parent populations should feature to optimise their use as powerful community resources for crop research, development and breeding.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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