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Abstract Background The synaptonemal complex (SC) is a proteinaceous tripartite structure used to hold homologous chromosomes together during the early stages of meiosis. The yeast ZIP1 and its homologues in other species have previously been characterised as the transverse filament protein of the synaptonemal complex. Proper installation of ZYP1 along chromosomes has been shown to be dependent on the axial element-associated protein, ASY1 in Arabidopsis. Results Here we report the isolation of the wheat (Triticum aestivum) ZYP1 (TaZYP1) and its expression profile (during and post-meiosis) in wild-type, the ph1b deletion mutant as well as in Taasy1 RNAi knock-down mutants. TaZYP1 has a putative DNA-binding S/TPXX motif in its C-terminal region and we provide evidence that TaZYP1 interacts non-preferentially with both single- and double-stranded DNA in vitro. 3-dimensional dual immunofluorescence localisation assays conducted with an antibody raised against TaZYP1 show that TaZYP1 interacts with chromatin during meiosis but does not co-localise to regions of chromatin where TaASY1 is present. The TaZYP1 signal lengthens into regions of chromatin where TaASY1 has been removed in wild-type but this appears delayed in the ph1b mutant. The localisation profile of TaZYP1 in four Taasy1 knock-down mutants is similar to wild-type but TaZYP1 signal intensity appears weaker and more diffused. Conclusions In contrast to previous studies performed on plant species where ZYP1 signal is sandwiched by ASY1 signal located on both axial elements of the SC, data from the 3-dimensional dual immunofluorescence localisation assays conducted in this study show that TaZYP1 signal only lengthens into regions of chromatin after TaASY1 signal is being unloaded. However, the observation that TaZYP1 loading appears delayed in both the ph1b and Taasy1 mutants suggests that TaASY1 may still be essential for TaZYP1 to play a role in SC formation during meiosis. These data further suggest that the temporal installation of ZYP1 onto pairing homologous chromosomes in wheat is different to that of other plant species and highlights the need to study this synaptonemal complex protein on a species to species basis.

Abstract Background In flowering plants, the anther is the site of male gametophyte development. Two major events in the development of the male germline are meiosis and the asymmetric division in the male gametophyte that gives rise to the vegetative and generative cells, and the following mitotic division in the generative cell that produces two sperm cells. Anther transcriptomes have been analyzed in many plant species at progressive stages of development by using microarray and sequence-by synthesis-technologies to identify genes that regulate anther development. Here we report a comprehensive analysis of rice anther transcriptomes at four distinct stages, focusing on identifying regulatory components that contribute to male meiosis and germline development. Further, these transcriptomes have been compared with the transcriptomes of 10 stages of rice vegetative and seed development to identify genes that express specifically during anther development. Results Transcriptome profiling of four stages of anther development in rice including pre-meiotic (PMA), meiotic (MA), anthers at single-celled (SCP) and tri-nucleate pollen (TPA) revealed about 22,000 genes expressing in at least one of the anther developmental stages, with the highest number in MA (18,090) and the lowest (15,465) in TPA. Comparison of these transcriptome profiles to an in-house generated microarray-based transcriptomics database comprising of 10 stages/tissues of vegetative as well as reproductive development in rice resulted in the identification of 1,000 genes specifically expressed in anther stages. From this sub-set, 453 genes were specific to TPA, while 78 and 184 genes were expressed specifically in MA and SCP, respectively. The expression pattern of selected genes has been validated using real time PCR and in situ hybridizations. Gene ontology and pathway analysis of stage-specific genes revealed that those encoding transcription factors and components of protein folding, sorting and degradation pathway genes dominated in MA, whereas in TPA, those coding for cell structure and signal transduction components were in abundance. Interestingly, about 50% of the genes with anther-specific expression have not been annotated so far. Conclusions Not only have we provided the transcriptome constituents of four landmark stages of anther development in rice but we have also identified genes that express exclusively in these stages. It is likely that many of these candidates may therefore contribute to specific aspects of anther and/or male gametophyte development in rice. In addition, the gene sets that have been produced will assist the plant reproductive community in building a deeper understanding of underlying regulatory networks and in selecting gene candidates for functional validation.

Abstract Background Chromosome pairing, recombination and DNA repair are essential processes during meiosis in sexually reproducing organisms. Investigating the bread wheat (Triticum aestivum L.) Ph2 (Pairing homoeologous) locus has identified numerous candidate genes that may have a role in controlling such processes, including TaMSH7, a plant specific member of the DNA mismatch repair family. Results Sequencing of the three MSH7 genes, located on the short arms of wheat chromosomes 3A, 3B and 3D, has revealed no significant sequence divergence at the amino acid level suggesting conservation of function across the homoeogroups. Functional analysis of MSH7 through the use of RNAi loss-of-function transgenics was undertaken in diploid barley (Hordeum vulgare L.). Quantitative real-time PCR revealed several T0 lines with reduced MSH7 expression. Positive segregants from two T1 lines studied in detail showed reduced MSH7 expression when compared to transformed controls and null segregants. Expression of MSH6, another member of the mismatch repair family which is most closely related to the MSH7 gene, was not significantly reduced in these lines. In both T1 lines, reduced seed set in positive segregants was observed. Conclusion Results presented here indicate, for the first time, a distinct functional role for MSH7 in vivo and show that expression of this gene is necessary for wild-type levels of fertility. These observations suggest that MSH7 has an important function during meiosis and as such remains a candidate for Ph2.

Abstract Background Our understanding of the mechanisms that govern the cellular process of meiosis is limited in higher plants with polyploid genomes. Bread wheat is an allohexaploid that behaves as a diploid during meiosis. Chromosome pairing is restricted to homologous chromosomes despite the presence of homoeologues in the nucleus. The importance of wheat as a crop and the extensive use of wild wheat relatives in breeding programs has prompted many years of cytogenetic and genetic research to develop an understanding of the control of chromosome pairing and recombination. The rapid advance of biochemical and molecular information on meiosis in model organisms such as yeast provides new opportunities to investigate the molecular basis of chromosome pairing control in wheat. However, building the link between the model and wheat requires points of data contact. Results We report here a large-scale transcriptomics study using the Affymetrix wheat GeneChip® aimed at providing this link between wheat and model systems and at identifying early meiotic genes. Analysis of the microarray data identified 1,350 transcripts temporally-regulated during the early stages of meiosis. Expression profiles with annotated transcript functions including chromatin condensation, synaptonemal complex formation, recombination and fertility were identified. From the 1,350 transcripts, 30 displayed at least an eight-fold expression change between and including pre-meiosis and telophase II, with more than 50% of these having no similarities to known sequences in NCBI and TIGR databases. Conclusion This resource is now available to support research into the molecular basis of pairing and recombination control in the complex polyploid, wheat.

Abstract Background In flowering plants, the anther is the site of male gametophyte development. Two major events in the development of the male germline are meiosis and the asymmetric division in the male gametophyte that gives rise to the vegetative and generative cells, and the following mitotic division in the generative cell that produces two sperm cells. Anther transcriptomes have been analyzed in many plant species at progressive stages of development by using microarray and sequence-by synthesis-technologies to identify genes that regulate anther development. Here we report a comprehensive analysis of rice anther transcriptomes at four distinct stages, focusing on identifying regulatory components that contribute to male meiosis and germline development. Further, these transcriptomes have been compared with the transcriptomes of 10 stages of rice vegetative and seed development to identify genes that express specifically during anther development. Results Transcriptome profiling of four stages of anther development in rice including pre-meiotic (PMA), meiotic (MA), anthers at single-celled (SCP) and tri-nucleate pollen (TPA) revealed about 22,000 genes expressing in at least one of the anther developmental stages, with the highest number in MA (18,090) and the lowest (15,465) in TPA. Comparison of these transcriptome profiles to an in-house generated microarray-based transcriptomics database comprising of 10 stages/tissues of vegetative as well as reproductive development in rice resulted in the identification of 1,000 genes specifically expressed in anther stages. From this sub-set, 453 genes were specific to TPA, while 78 and 184 genes were expressed specifically in MA and SCP, respectively. The expression pattern of selected genes has been validated using real time PCR and in situ hybridizations. Gene ontology and pathway analysis of stage-specific genes revealed that those encoding transcription factors and components of protein folding, sorting and degradation pathway genes dominated in MA, whereas in TPA, those coding for cell structure and signal transduction components were in abundance. Interestingly, about 50% of the genes with anther-specific expression have not been annotated so far. Conclusions Not only have we provided the transcriptome constituents of four landmark stages of anther development in rice but we have also identified genes that express exclusively in these stages. It is likely that many of these candidates may therefore contribute to specific aspects of anther and/or male gametophyte development in rice. In addition, the gene sets that have been produced will assist the plant reproductive community in building a deeper understanding of underlying regulatory networks and in selecting gene candidates for functional validation.

Beer flavor is primarily impacted by malt kilning and the choice of yeast/hops in the beer recipe. Although barley malt is the material backbone of most beers, variety has until recently been largely overlooked with respect to flavor differences. In this study, 11 malt variety samples from multiple Australian and international (UK, Canada, China) growing regions were infusion mashed (65 °C) at laboratory scale to produce unboiled wort to investigate differences between the flavor profiles observed with sensory assessment and headspace-SPME gas chromatography-mass spectrometry (HS-SPME GC-MS). Sensory evaluation identified wort flavor differences with the control heritage samples, Maris Otter/Schooner, having the highest overall flavor complexity and acceptability. The Chinese malted Chinese/Canadian samples had the lowest overall flavor complexity rankings. Overall, flavor complexity was correlated with KI, malt protein (negative), and β-glucosidase (negative), while sweetness intensity was correlated with limit dextrinase and pH. HS-SPME GC-MS analysis focused only on compounds that were significantly different between varieties (ANOVA, P ≤ 0.05). Overall, 107 compounds were identified with significantly different levels between the varietal worts. The resultant PCA plots (overall, aldehydes, alcohols, esters, organic acids, terpenes, ketones) supported the sensory assessment, with Maris Otter and the Australian samples clustering in different PCA sectors compared to the Chinese malted Canadian/Chinese samples. These findings provide a basis for key compound identifications that influence malt flavor through the brewing process. The results have the potential to assist barley breeders in selecting optimized germplasm for future variety development and can assist maltsters and brewers to consistently target desired flavors for finished beers and potentially whisk(e)y. Supplemental data for this article is available online at https://doi.org/10.1080/03610470.2022.2041156. [ABSTRACT FROM AUTHOR]

A largely defined series of hydrolytic enzymes active during malting and/or mashing, substantially determine the quality, profitability, and efficiency of the brewing process. These enzymes potentially hydrolyze starch, proteins and cell wall non-starch polysaccharides including β-glucan and arabinoxylan. Commercial malts (94) were assayed for the DP enzymes (limit dextrinase, beta/α-amylase), and NSP hydrolyzing enzymes (β-glucanase, xylanase, arabinofuranosidase, β-glucosidase). The levels of enzyme activity were related to conventional measures of malt quality such as extract, fermentability, protein, KI, DP, friability, wort viscosity, FAN, and β-glucan. These parameters were interrelated with less conventional measures of malt quality including coarse extract and fermentability (modified infusion mash 65 °C), lautering efficiency, the Small-scale Wort 'I' Filtration Test (SWIFT), and viscosity. Substantial variation was observed between the malt samples for all enzymes assayed. Australian barley, whether malted in Australia (n = 61) or China (n = 24), was observed to be of comparable quality. A limited set of Canadian barley samples (n = 9) were malted in China and produced malts with somewhat higher levels of extract, AAL, and some enzymes. Remarkably, the level of limit dextrinase was observed to be almost double that from previous investigations. Greater levels of steep water aeration were proposed to explain this dramatic increase. The interrelationships between the enzyme activities and malt quality identified, enable potential selection of novel malt quality parameters that are more predictive of a malt's brewing performance (efficiency and quality) than current measures to provide a malt quality assessment system based on 'functional' malt quality. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Micronutrients such as zinc and iron are critical for human health. For the world's population that relies on cereal products to obtain micronutrients, the bioavailability (absorption of nutrients in the gut) can be hindered by an anti‐nutritional compound, phytate. Phytate accumulation in grain is affected by soil properties including phosphorus availability and arbuscular mycorrhizal (AM) fungi. Here, we investigated the effects of AM fungi and soil phosphorus fertilization on micronutrient bioavailability in durum wheat and found that fertilization greatly decreased the bioavailability of micronutrients, but AM fungi can take up more micronutrients, which can lead to improved bioavailability when the soil is not fertilized. Summary: The bioavailability of micronutrients (zinc [Zn] and iron [Fe]) in cereal crops such as durum wheat is critically important for human nutrition. Bioavailability is a product of complex interactions between plant phosphorus (P) uptake and storage in grain (as phytate), and plant micronutrient uptake. The bioavailability of Zn and Fe in cereal grain is affected by soil nutrient concentrations and associations with arbuscular mycorrhizal (AM) fungi, but has been scarcely studied.A geographically diverse collection of 101 durum wheat genotypes was surveyed for grain bioavailability of Zn and Fe. Ten genotypes were then selected and grown with and without AM fungal inoculation and soil P fertilization to understand the effects of manipulating soil P availability and uptake on micronutrient bioavailability.The strongest negative effect on grain micronutrient bioavailability was soil P fertilization, however, it also led to increased grain weight. Crop variety selection had the greatest variation in the P‐fertilized soil, but AM fungal inoculation had a positive effect on bioavailability in one variety in the non‐fertilized soil.In order to grow more nutritious durum wheat crops, variety selection and AM fungal inoculation are important considerations. In general, there is a trade‐off between grain weight (yield) and micronutrient bioavailability in grain that could be addressed through breeding P‐deficiency tolerant varieties. [ABSTRACT FROM AUTHOR]