Biology subjects

Trafford, K.

Publications and source records attributed to Trafford, K..

7 recordsLinked to original sources

bioRxiv2026

Temporal genomic imprinting regulates grain filling in barley

In cereals, the persistent endosperm accumulates starch and storage proteins, making their grains a major source of food and feed. Early grain development is epigenetically controlled through the parent-of-origin-specific expression of imprinted genes in the endosperm that regulate endosperm proliferation, nutrient accumulation and embryo nourishment. Imprinted genes have been identified in several major cereals, and a few have been functionally characterized. However, it is unclear how imprinted genes regulate the accumulation of storage compounds in cereal grains. Through spatiotemporal transcriptome analysis of 255 imprinted genes in barley (Hordeum vulgare), we identify endosperm transfer cells in grains as a hotspot of expression of imprinted genes. Furthermore, we show that transcription factor LYS3 dynamically regulates grain filling in barley through early expression of the maternal allele, followed by partial activation of the paternal allele.

plant biology↗

bioRxiv2026

Two redundant paralogs of MAR1-BINDING FILAMENT PROTEIN affect B-type granule initiation in wheat

Starch synthesis in wheat endosperm involves the initiation of large A-type starch granules during early grain development, followed by small B-type granules in later grain development. It is established that MAR-BINDING FILAMENT-LIKE PROTEIN 1 (MFP1) plays an important role in granule initiation in Arabidopsis chloroplasts, but how it influences A- and B-type initiations in wheat amyloplasts is not known. We discovered that due to a gene duplication in cereals, wheat contains two MFP1 paralogs, MFP1.1 and MFP1.2, which are both expressed in the developing endosperm. We generated a series of durum wheat mutants defective in all homoeologs of either MFP1.1 or MFP1.2, or both. While starch granule size distributions and granule morphology of mfp1.1 and mfp1.2 mutants were identical to those of the wild-type, the mfp1.1 mfp1.2 mutants had fewer, but larger B-type granules - suggesting that the two paralogs play redundant roles in B-type granule initiation. Consistent with this, both paralogs interacted with B-GRANULE CONTENT 1 (BGC1), a key protein required for proper B-type granule initiation in wheat, and both paralogs could partially complement defects in starch initiation in the Arabidopsis mfp1 mutant. Our work demonstrates that MFP1 is required for establishing correct starch granule number in non-photosynthetic amyloplasts, but its role in wheat is limited to B-type granule initiation. One-sentence summaryWheat has two MFP1 paralogs that interact with the granule initiation protein, BGC1 and influence B-type granule initiation in non-photosynthetic amyloplasts of endosperm.

plant biology↗

bioRxiv2026

Wheat mutants lacking Starch Synthase 1 have altered starch composition and cell wall content

Starch Synthase 1 (SS1) participates in the synthesis of amylopectin. To determine its role in hexaploid bread wheat, we selected and combined TILLING mutations for each homoeologue to create two independent SS1-deficient lines. The lines, which have different combinations of ss1 mutations, both lacked SS1 protein. Both lines exhibited mild but significant changes to starch phenotype, including fewer short amylopectin chains, a slight increase in B-type starch granules and a modest increase in amylose content. Lack of SS1 also led to changes in the thermal properties of starch measured by differential scanning calorimetry including reduced enthalpy, and increased gelatinization temperature. Despite the changes to starch properties, the starch contents of the mutant lines compared to wild types were within the normal range, as were grain weight and protein content. However, the concentration of total- and water-extractable arabinoxylan, and MLG, were increased in white flour compared to wild-type controls. HighlightLack of SS1 led to changes in starch molecular structure and thermal behavior. Starch content and grain weight were normal but cell wall polysaccharides in white flour were increased.

plant biology↗

bioRxiv2021

Characterization of wheat lacking B-type starch granules

The physicochemical and agronomic properties of a new form of bread wheat, lacking B-type starch granules (BlessT) were assessed. Three BlessT mutant lines, made by combining homoeologous deletions of BGC1, a gene responsible for the control of B-granule content were compared with two sibling lines with normal starch phenotype and the parent line, cv. Paragon. Quantification of starch granule size and number in developing grain confirmed the lack of small, B-type starch granules throughout development in BlessT. Most starch, flour, grain and loaf characteristics did not vary between BlessT and the wild type sibling controls. However, BlessT starches had higher water absorption, reduced grain hardness and higher protein content, and dough made from BlessT flour required more water and had increased elasticity. Despite the lack of B-granules, BlessT lines do not display a significant decrease in total starch content suggesting that it should be possible to produce commercial wheat varieties that lack B-type starch granules without compromising yield. These findings support the potential utility of this novel type of wheat as a specialist crop in applications ranging from bread making and alcohol production to improved industrial starch products.

plant biology↗

bioRxiv2019

LYS3 encodes a prolamin-box-binding transcription factor that controls embryo growth in barley and wheat

Mutations at the LYS3 locus in barley have multiple effects on grain development, including an increase in embryo size and a decrease in endosperm starch content. The gene underlying LYS3 was identified by genetic mapping and mutations in this gene were identified in all four barley lys3 alleles. LYS3 encodes a transcription factor called Prolamin Binding Factor (PBF). Its role in controlling embryo size was confirmed using wheat TILLING mutants. To understand how PBF controls embryo development, we studied its spatial and temporal patterns of expression in developing grains. The PBF gene is expressed in both the endosperm and the embryos, but the timing of expression in these organs differs. PBF expression in wild-type embryos precedes the onset of embryo enlargement in lys3 mutants, suggesting that PBF suppresses embryo growth. We predicted the down-stream target genes of PBF in wheat and found them to be involved in a wide range of biological processes, including organ development and starch metabolism. Our work suggests that PBF may influence embryo size and endosperm starch synthesis via separate gene control networks. HIGHLIGHTSO_LILYS3 encodes a transcription factor called Prolamin Binding Factor (PBF) that is expressed in grains only. C_LIO_LIWheat and barley LYS3/PBF mutants have enlarged embryos suggesting that this gene suppresses embryo growth. C_LIO_LIThe down-stream target genes of PBF in wheat are predicted to be involved in a wide range of biological processes including organ development and starch metabolism. C_LI

plant biology↗

bioRxiv2019

TRA1: a locus responsible for controlling Agrobacterium-mediated transformability in barley.

In barley (Hordeum vulgare L.), Agrobacterium-mediated transformation efficiency is highly dependent on genotype with very few cultivars being amenable to transformation. Golden Promise is the cultivar most widely used for barley transformation and developing embryos are the most common donor tissue. We tested whether barley mutants with abnormally large embryos were more or less amenable to transformation and discovered that mutant M1460 had a transformation efficiencies similar to that of Golden Promise. The large-embryo phenotype of M1460 is due to mutation at the LYS3 locus. There are three other barley lines with independent mutations at the same LYS3 locus, and one of these, Riso1508 has an identical missense mutation to that in M1460. However, none of the lys3 mutants except M1460 were transformable showing that the locus responsible for transformation efficiency, TRA1, was not LYS3 but another locus unique to M1460. To identify TRA1, we generated a mapping population by crossing M1460 to the cultivar Optic, which is recalcitrant to transformation. After four rounds of backcrossing to Optic, plants were genotyped and their progeny were tested for transformability. Some of the progeny lines were transformable at high efficiencies similar to those seen for the parent M1460 and some were not transformable, like Optic. A region on chromosome 2H inherited from M1460 is present in transformable lines only. We propose that one of the 225 genes in this region is TRA1.

plant biology↗

bioRxiv2019

A carbohydrate-binding protein, FLOURY ENDOSPERM 6 influences the initiation of A- and B-type starch granules in wheat.

Previously, we identified a quantitative trait locus on the group 4 chromosomes of Aegilops and bread wheat that controls B-type starch-granule content. Here, we identify a candidate gene by fine-mapping in Aegilops and confirm its function using wheat TILLING mutants. This gene is orthologous to the FLOURY ENDOSPERM 6 (FLO6) gene of rice and barley and the PTST2 gene of Arabidopsis. In Triticeae endosperm, reduction in the gene dose of functional FLO6 alleles results in reduction, or loss, of B-granules. This is due to repression of granule initiation in late-grain development, but has no deleterious impact on the synthesis of A-granules. The complete absence of functional FLO6, however, results in reduced numbers of normal A-type and B-type granules and the production of highly-abnormal granules that vary in size and shape. This polymorphous starch seen in a wheat flo6 triple mutant is similar to that observed in the barley mutant Franubet. Analysis of Franubet (fractured Nubet) starch suggests that the mutant A-granules are not fractured but compound, due to stimulation of granule initiation in plastids during early-grain development. Thus, in different situations in Triticeae, FLO6 either stimulates or represses granule initiation.

plant biology↗