High post-anthesis temperature effects on bread wheat (Triticum aestivum L.) grain transcriptome during early grain-filling

A - Papers appearing in refereed journals

Kino, R. I., Pellny, T. K., Mitchell, R. A. C., Gonzalez-Uriarte, A. and Tosi, P. 2020. High post-anthesis temperature effects on bread wheat (Triticum aestivum L.) grain transcriptome during early grain-filling. BMC Plant Biology. 20, p. 170. https://doi.org/10.21203/rs.2.18309/v1

AuthorsKino, R. I., Pellny, T. K., Mitchell, R. A. C., Gonzalez-Uriarte, A. and Tosi, P.

Background: High post-anthesis (p.a) temperatures significantly reduce mature grain weight in wheat and other cereals. However, the mechanisms through which this reduction occurs are not entirely known. It has been suggested that the pericarp may control grain expansion and weight potential, but this interaction has not been investigated under high p.a. temperatures. Disreregulation, caused by high p.a. temperatures, of pericarp-localised genes involved in cell wall expansion may limit the expansion of the endosperm and contribute to a reduction in mature grain size. Here the effect of high p.a. temperature on the transcriptome of the outer-pericarp and endosperm of the wheat grain during early grain-filling was investigated via RNA-Seq and is discussed in the context of grain moisture dynamics during early grain development and of mature grain weight

Results: High p.a. temperatures applied from 6-days after anthesis (daa) and until 18daa reduced the ability of the grain to accumulate water, with total grain moisture and percentage moisture content of the grain being significantly reduced from 14daa onwards. High p.a. temperatures applied from 6daa and for a minimum of 4-daysalso significantly reduced mature grain weight. Comparison of our RNA-Seq data from whole grains, with existing data sets from isolated outer-pericarp and endosperm tissues enabled the identification of subsets of genes whose expression was significantly affected by high p.a. temperature and predominantly expressed in either tissue. Hierarchical clustering and gene ontology analysis resulted in the identification of a number of genes implicated in the regulation of cell wall expansion, predominantly expressed in the outer-pericarp and significantly down-regulated under high p.a. temperatures; these included endoglucanase, xyloglucan endotransglycosylases and a β-expansin. An over-representation of genes involved in the ‘cuticle development’ functional pathway expressed in the outer-pericarp and affected by high p.a. temperatures was also observed.

Conclusions: High p.a. temperatures induced down regulation of genes involved in the control of pericarp cell wall expansion and occurred concomitantly to a reduction in the potential for grain moisture accumulation, which is the driving force for endosperm cell volume enlargement and an important determinant of final grain sink capacity. This suggests that high p.a. temperatures impairs the coordination of the development of the different grain tissues, resulting in reduced expansion of the maternal layers and therefore, reduce mature grain weight.

KeywordsRNA-Seq ; Wheat; Grain development; Post-anthesis; Temperature; Cell wall; Pericarp; Transciptomics
Year of Publication2020
JournalBMC Plant Biology
Journal citation20, p. 170
Digital Object Identifier (DOI)https://doi.org/10.21203/rs.2.18309/v1
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
Online16 Apr 2020
Publication process dates
Accepted31 Mar 2020
PublisherBiomed Central Ltd

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