Expression of TaCYP78A3, a gene encoding cytochrome P450 CYP78A3 protein in wheat (Triticum aestivum L.), affects seed size

Abstract

Several studies have described quantitative trait loci (QTL) for seed size in wheat, but the relevant genes and molecular mechanisms remain largely unknown. Here we report the functional characterization of the wheat TaCYP78A3 gene and its effect on seed size. TaCYP78A3 encoded wheat cytochrome P450 CYP78A3, and was specifically expressed in wheat reproductive organs. TaCYP78A3 activity was positively correlated with the final seed size. Its silencing caused a reduction of cell number in the seed coat, resulting in an 11% decrease in wheat seed size, whereas TaCYP78A3 over-expression induced production of more cells in the seed coat, leading to an 11-48% increase in Arabidopsis seed size. In addition, the cell number in the final seed coat was determined by the TaCYP78A3 expression level, which affected the extent of integument cell proliferation in the developing ovule and seed. Unfortunately, TaCYP78A3 over-expression in Arabidopsis caused a reduced seed set due to an ovule developmental defect. Moreover, TaCYP78A3 over-expression affected embryo development by promoting embryo integument cell proliferation during seed development, which also ultimately affected the final seed size in Arabidopsis. In summary, our results indicated that TaCYP78A3 plays critical roles in influencing seed size by affecting the extent of integument cell proliferation. The present study provides direct evidence that TaCYP78A3 affects seed size in wheat, and contributes to an understanding of the cellular basis of the gene influencing seed development.

Virus-Induced Gene Silencing Identifies an Important Role of the TaRSR1 Transcription Factor in Starch Synthesis in Bread Wheat

“…In this study, the full-length cDNA sequence of this copy, its conserved cDNA fragment (284 bp) used to construct the BSMV-TaRSR1 vector, and the other two copies (1AS and 1BS) in bread wheat A and B subgenomes are indicated in Figure S1. Because there are high similarities in cDNA or protein sequences among three or more copies of a gene in allohexaploid bread wheat, VIGS method usually results in the simultaneous silencing of three copies for the targeted gene in bread wheat [47]. In this study, similarly, the chosen cDNA fragment of TaRSR1 (1DS) for VIGS silencing also had high similarities (99.1%) to those of the other two copies (Figure S1), and thus, all three copies of TaRSR1 gene could be simultaneously silenced in this study.…”

Major genes determining yield-related traits in wheat and barley

“…This shows that a particular function of a gene of interest should be established in a target species. Some information on expected function might be derived from the temporal and spatial expression profile of selected genes (Christiansen et al 2011; Ma et al 2015b; Song et al 2012; Zalewski et al 2014). …”

“…Virus-induced gene silencing (VIGS) of the gene in wheat led to a reduced cell number of the seed coat and decreased seed size. Ectopic overexpression of the gene in A. thaliana caused 11 to 48% increase of seed size (Ma et al 2015b). …”

Altered expression of maize PLASTOCHRON1 enhances biomass and seed yield by extending cell division duration

“…Of these, gibberellins (GAs) were shown to play an important role, because lines overexpressing the rate-limiting GA biosynthetic enzyme GA20-OXIDASE had larger leaves due to an increase in the leaf elongation rate (LER) and the number of dividing cells13. More recently, a cytochrome P450 CYP78A, named KLUH, was shown to regulate vegetative and reproductive organ growth across plant species by promoting cell proliferation likely through generation of a mobile growth-promoting signal161718192021. In rice, PLASTOCHRON1 ( PLA1 ) that belongs to the same class of CYP78A as KLUH affects the timing of leaf initiation and vegetative growth22.…”