Overexpression of the WAPO-A1 gene increases the number of spikelets per spike in bread wheat

Wittern, Lukas; Barrero, José M.; Bovill, William D.; Verbyla, Klara L.; Hughes, Trijntje; Swain, Stephen M.; Steed, Gareth; Webb, Alex; Gardner, Keith A.; Greenland, Andrew J.; Jacobs, John; Frohberg, Claus; Schmidt, Ralf-Christian; Cavanagh, Colin; Rohde, Antje; Davey, Mark W.; Hannah, Matthew A.

doi:10.1038/s41598-022-18614-w

Cited by 4 publications

(5 citation statements)

References 70 publications

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“…Thus, APO1 appears to stimulate cell division in the IM. This could also be true in wheat where strong branching defects are reported in wapo1 mutants (Kuzay et al ., 2022; Wittern et al ., 2022). However, APO1 expression in the vegetative SAM negatively affects the number of leaves and branches produced (Ikeda et al ., 2005, 2007; Ikeda‐Kawakatsu et al ., 2009).…”

Section: Ufo Regulates Diverse Developmental Stepsmentioning

confidence: 99%

“…APO1 is also involved in repressing tillers as their number is increased in the apo1 mutant (Ikeda et al ., 2005) and strongly decreased when APO1 is overexpressed (Ikeda‐Kawakatsu et al ., 2009; Ookawa et al ., 2010). A similar phenomenon occurs in wheat WAPO1 overexpressors (Wittern et al ., 2022). Therefore, UFO appears to repress vegetative meristems in monocots and thus have opposite effects between vegetative and inflorescence meristems.…”

Section: Ufo Regulates Diverse Developmental Stepsmentioning

confidence: 99%

“…Conversely, dominant apo1‐D mutants expressing APO1 at higher levels have hyper‐branched inflorescences (Ikeda et al ., 2007; Ikeda‐Kawakatsu et al ., 2009). Similar results were found in wheat (a grass developing a spike inflorescence): the spikelet number per spike is reduced by a mutation in WAPO1 and increased when WAPO1 expression level is higher (Kuzay et al ., 2022; Wittern et al ., 2022). Thus, in contrast to what is observed in dicots, a major role of UFO in cereals is to promote IM/branch meristem identity.…”

Section: Ufo Regulates Diverse Developmental Stepsmentioning

confidence: 99%

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Thinking outside the F‐box: how UFO controls angiosperm development

Rieu,

Arnoux‐Courseaux,

Tichtinsky

et al. 2023

New Phytologist

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SummaryThe formation of inflorescences and flowers is essential for the successful reproduction of angiosperms. In the past few decades, genetic studies have identified the LEAFY transcription factor and the UNUSUAL FLORAL ORGANS (UFO) F‐box protein as two major regulators of flower development in a broad range of angiosperm species. Recent research has revealed that UFO acts as a transcriptional cofactor, redirecting the LEAFY floral regulator to novel cis‐elements. In this review, we summarize the various roles of UFO across species, analyze past results in light of new discoveries and highlight the key questions that remain to be solved.

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Section: Ufo Regulates Diverse Developmental Stepsmentioning

confidence: 99%

Section: Ufo Regulates Diverse Developmental Stepsmentioning

confidence: 99%

Section: Ufo Regulates Diverse Developmental Stepsmentioning

confidence: 99%

See 1 more Smart Citation

Thinking outside the F‐box: how UFO controls angiosperm development

Rieu,

Arnoux‐Courseaux,

Tichtinsky

et al. 2023

New Phytologist

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“…However, the introgression of the beneficial alleles into elite material has seldom led to significant increases in yield. For example, the increase in expression of WAPO1 leads to increased spikelet numbers, which does not translate into yield gains due to increased spikelet abortion ( Wittern et al , 2022 ) and decreased floret survival ( Kuzay et al , 2022 ). Targeting the number of florets rather than spikelets, the reduced function allele of GRAIN NUMBER INCREASE 1 ( GNI1 ) has been shown to confer yield increases by reducing floret abortion compared with the wild-type GNI1 allele, which functions as a rachilla growth inhibitor ( Sakuma et al , 2019 ).…”

Section: Introductionmentioning

confidence: 99%

Delayed development of basal spikelets in wheat explains their increased floret abortion and rudimentary nature

Backhaus

Griffiths

Cruces

et al. 2023

Journal of Experimental Botany

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Large differences exist in the number of grains per spikelet across an individual wheat (Triticum aestivum L.) spike. The central spikelets produce the highest number of grains while apical and basal spikelets are less productive, and the most basal spikelets are commonly only formed rudimentary. Basal spikelets are delayed in initiation, yet they continue to develop and produce florets. The precise timings or the cause of their abortion remains largely unknown. Here, we investigated the underlying causes of basal spikelet abortion using shading applications in the field. We found that basal spikelet abortion is likely the consequence of complete floret abortion, as both occur concurrently and have the same response to shading treatments. We detected no differences in assimilate availability across the spike. Instead, we show that the reduced developmental age of basal florets pre-anthesis is strongly associated with their increased abortion. Using the developmental age pre-abortion, we were able to predict final grain set per spikelet across the spike, alongside the characteristic gradient in number of grains from basal to central spikelets. Future efforts to improve spikelet homogeneity across the spike could thus focus on improving basal spikelet establishment and increasing floret development rates pre-abortion.

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“…However, the introgression of the beneficial alleles into elite material has seldom led to significant increases in yields. For example, the increase in expression of WAPO1 leads to increased spikelet numbers, which does not translate into yield gains due to increased spikelet abortion (Wittern et al, 2022) and decreased floret survival (Kuzay et al, 2022). Targeting the number of florets rather than spikelets, the reduced-function allele of GRAIN NUMBER INCREASE 1 ( GNI1 ) has been shown to confer yield increases by reducing floret abortion compared to the wildtype GNI1 allele, which functions as a rachilla growth inhibitor (Sakuma et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Delayed development of basal spikelets in wheat explains their increased floret abortion and rudimentary nature

Backhaus

Griffiths

Cruces

et al. 2023

Preprint

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Wheat (Triticum aestivum L.) breeding efforts have increased grain yield predominantly by raising grain numbers per spikelet, rather than grain weight or spikelet number. However, across a single spike large differences exist in the number of grains per spikelet. The central spikelets produce the highest number of grains in any given genotype while apical and basal spikelets are less productive. Basal spikelets are delayed in development just after initiation and are smaller and less advanced than central spikelets already by the glume primordium stage. However, basal spikelets continue to develop and produce florets until much later in the wheat growth cycle. The precise timings or the cause of their growth cessation, and subsequent abortion, is largely unknown. In this study we investigated the underlying causes of rudimentary basal spikelet abortion. We investigated basal spikelet development in four UK winter wheat varieties as well as a set of near-isogenic lines for VRT-A2 (VEGETATIVE TO REPRODUCTIVE TRANSITION 2) using shading applications in the field. We propose that basal spikelet abortion is likely the consequence of complete floret abortion as both occur at the same time and have the same response to shading treatments. Furthermore, we found that the developmental age of florets pre-abortion is an important factor for their likelihood to survive and develop viable seed. Previously, it had been proposed that reduced assimilate availability in the base of the spike leads to increased abortion. Re-analysis of published data alongside data presented here, however, does not support this model. We found that rather than assimilate availability, it is the reduced developmental age of basal florets before abortion that correlates with increased abortion. Using the floret Waddington developmental stage pre-abortion, we were able to predict final grain set per spikelet across the spike, alongside the characteristic gradient in number of grains from basal to central spikelets. We found that advancing past Waddington stage 5.5 seems to be important for floret survival and that most florets in basal spikelets had not reached this stage at the onset of floret abortion. The abortion of all florets could therefore be the reason for their rudimentary appearance in the mature spike, suggesting that basal spikelet abortion is simply the consequence of all florets inside the spikelet being aborted and thus all other spikelet structures (e.g., lemma, rachilla, glume) also ceasing to develop. Future efforts to improve spikelet homogeneity across the spike could thus focus on improving basal spikelet establishment and increasing floret development rates pre-abortion.

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Overexpression of the WAPO-A1 gene increases the number of spikelets per spike in bread wheat

Cited by 4 publications

References 70 publications

Thinking outside the F‐box: how UFO controls angiosperm development

Thinking outside the F‐box: how UFO controls angiosperm development

Delayed development of basal spikelets in wheat explains their increased floret abortion and rudimentary nature

Delayed development of basal spikelets in wheat explains their increased floret abortion and rudimentary nature

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