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The aim of this study was to assess the variation in grain quality traits among mutant lines of winter feed barley. Nine mutant lines derived from the advanced breeding line Kt3029 and 10 mutant lines derived from variety GA-Luttrell along with their parent forms were evaluated. The study was conducted at the Institute of Agriculture - Karnobat during the period 2015-2017. Test weight, 1000-grain weight, the content of protein, starch, lysine, fat, ash, and fibre were determined. Significant differences between the mutant lines and the parent forms for the studied traits were observed. Significantly higher protein content compared to parent was found in the grain of mutant lines 22/1-5, 22/2-10 and 22/1-12 from line Kt3029 and 26/1-1, 26/1-3 and 26/2-11 from variety GA-Luttrell. The grain of mutant line 26/2-12 had the best combination of protein and starch. Mutant lines 22/1-11 and 22/1-12 from Kt3029 and 26/1-1, 26/2-1 and 26/2-12 from variety GA-Luttrell showed a good combination between protein content and 1000-grain weight. Those mutant lines can be included in the breeding program for the development of varieties with improved feed quality. [ABSTRACT FROM AUTHOR]

Background and objectives: There are no published data on the effect of sowing rate on rice grain quality traits of medium‐ and short‐grain cultivars within the Australian environment. Studies that have reported on the impact of sowing rate on grain quality in other rice growing regions have assessed differences between densities below 100 plants/m2, which is the minimum target for Australian grown rice. Furthermore, the cultivars evaluated were long‐grain cultivars only. The effect of sowing rate (25–150 kg/ha) on the quality traits of a short (YRK5)‐ and medium (Viand)‐grain rice cultivar was investigated over two seasons. Nitrogen (N) application was included in the study as the appropriate combination of sowing and N rate for maximum yield for both cultivars was unknown. Findings: Sowing and N rate affected the number of grains per panicle and plants established per m2 of both cultivars; however, changes in these parameters did not affect crop yield. The number of grains per panicle affected thousand‐grain weight (TGW) and head rice yield (HRY; the percentage of grain that remains whole or at least 75% of the original length after milling), and the response differed between cultivars. Decreasing sowing rate increased the number of grains per panicle, reduced grain length and TGW, and slightly increased HRY in Viand. In YRK5, decreased sowing rate increased TGW and in season two reduced HRY. Protein content was negatively correlated with TGW and positively correlated with HRY. There were no consistent differences in the physicochemical and cooking parameters between densities over both seasons in both cultivars. Conclusion: These results indicate that plant density has an indirect effect on milling quality by influencing TGW, which affected total protein content, and thus, HRY and the response differ between cultivars. Furthermore, this study demonstrated that within a population of 18 to 231 plants/m2 at establishment, the physicochemical and cooking parameters are not affected by sowing rate. Significance and novelty: This study is the first to analyze the grain physicochemical and cooking quality parameters at densities above 100 plants/m2 and evaluate the effect of sowing rate on the grain quality of differing grain types within Australia. Comparisons between the low (50–70 kg/ha) and standard sowing rate (130–150 kg/ha) revealed no difference in HRY, and these results are important to farmers and demonstrate a reduction in plant density due to poor establishment, environmental or bird damage does not affect crop yield or grain quality and thus their economic return. [ABSTRACT FROM AUTHOR]

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Grain-filling, as the final growth stage of rice, is sensitive to environmental temperature change. Previous studies mainly concerned about the effects of high temperature stress during grain-filling on rice growth, and most experiments were carried out with pot for cultivating rice and greenhouse for warming. This research investigated the response of rice grain-filling of superior spikelets (SS) and inferior spikelets (IS) of two japonica cultivars to elevated temperature during grain-filling stage under open-field warming conditions in lower reaches of Yangtze River Basin using free-air temperature enhancement facility. Results indicated that rice yield was not significantly changed by warming less than 4°C. SS and IS showed different responses to elevated temperature during the grain-filling stage, whereas there were similar trends between two cultivars and years. For SS, although elevated temperature enhanced its filling rate during the early grain-filling period, and caused a shorter grain-filling period and a lighter grain weight; for IS, elevated temperature improved its grain weight by enhancing its filling rate during middle and late grain-filling period due to the increased number of days with suitable temperature. For both SS and IS, key starch biosynthesis enzymes and indole-3-acetic acid content exhibited generally a similar dynamics trend with grain-filling rates, and these sink strength parameters presented higher levels under elevated temperature relative to natural temperature for IS during middle and late grain-filling period. Consequently, warming less than 4°C presented different influences on SS and IS; the improvement of IS filling under warming regime was associated with the intensification of grain sink strength. [ABSTRACT FROM AUTHOR]

Cytokinins (CKs) are a class of phytohormones playing essential roles in various biological processes. However, the mechanisms underlying CK transport as well as its function in plant growth and development are far from being fully elucidated. Here, we characterize the function of PURINE PERMEASE1 (OsPUP1) in rice (Oryza sativa L.). OsPUP1 was predominantly expressed in the root, particularly in vascular cells, and CK treatment can induce its expression. Subcellular localization analysis showed that OsPUP1 was predominantly localized to the endoplasmic reticulum (ER). Overexpression of OsPUP1 resulted in growth defect of various aerial tissues, including decreased leaf length, plant height, grain weight, panicle length, and grain number. Hormone profiling revealed that the CK content was decreased in the shoot of OsPUP1-overexpressing seedling, but increased in the root, compared with the wild type. The CK content in the panicle was also decreased. Quantitative reverse transcription-PCR (qRT-PCR) analysis using several CK type-A response regulators (OsRRs) as the marker genes suggested that the CK response in the shoot of OsPUP1-overexpressing seedling is decreased compared to the wild type when CKs are applied to the root. Genetic analysis revealed that BG3/OsPUP4, a putative plasma membrane-localized CK transporter, overcomes the function of OsPUP1. We hypothesize that OsPUP1 might be involved in importing CKs into ER to unload CKs from the vascular tissues by cell-to-cell transport.

Wheat (Triticum aestivum L.) is an important cereal crop globally as well as in India and yield improvement programs encounter a strong impediment from ever-evolving rust pathogens. Hence, durable rust resistance is always a priority trait for wheat breeders globally. Grain weight, represented as thousand grain weight (TGW), is the most important yield-contributing trait in wheat. In the present study high TGW has been transferred into two elite Indian wheat cultivars PBW343 and PBW550 from a high TGW genotype, Rye selection 111, selected from local germplasm. In the background of PBW343 and PBW550, an increase in TGW upto 27.34 and 18% was observed, respectively (with respect to recipient parents), through conventional backcross breeding with phenotypic selections in 3 years replicated RBD trials. Resistance to leaf rust and stripe rust has been incorporated in the high TGW version of PBW550 through marker assisted pyramiding of stripe rust resistance gene Yr15 using marker Xuhw302, and a pair of linked leaf rust and stripe rust resistance genes Lr57-Yr40 using marker Ta5DS-2754099_kasp23. Improved versions of PBW550 with increased TGW ranging from 45.0 to 46.2 g (up to a 9% increase) and stacked genes for stripe and leaf rust resistance have been developed. This study serves as proof of utilizing conventional breeding and phenotypic selection combined with modern marker assisted selection in improvement of important wheat cultivars as a symbiont of conventional and moderan techniques.

Wheat (Triticum aestivum L.) is an important cereal crop globally as well as in India and yield improvement programs encounter a strong impediment from ever-evolving rust pathogens. Hence, durable rust resistance is always a priority trait for wheat breeders globally. Grain weight, represented as thousand grain weight (TGW), is the most important yield-contributing trait in wheat. In the present study high TGW has been transferred into two elite Indian wheat cultivars PBW343 and PBW550 from a high TGW genotype, Rye selection 111, selected from local germplasm. In the background of PBW343 and PBW550, an increase in TGW upto 27.34 and 18% was observed, respectively (with respect to recipient parents), through conventional backcross breeding with phenotypic selections in 3 years replicated RBD trials. Resistance to leaf rust and stripe rust has been incorporated in the high TGW version of PBW550 through marker assisted pyramiding of stripe rust resistance gene Yr15 using marker Xuhw302 , and a pair of linked leaf rust and stripe rust resistance genes Lr57-Yr40 using marker Ta5DS-2754099_kasp23. Improved versions of PBW550 with increased TGW ranging from 45.0 to 46.2 g (up to a 9% increase) and stacked genes for stripe and leaf rust resistance have been developed. This study serves as proof of utilizing conventional breeding and phenotypic selection combined with modern marker assisted selection in improvement of important wheat cultivars as a symbiont of conventional and moderan techniques. [ABSTRACT FROM AUTHOR]

Cytokinins (CKs) are a class of phytohormones playing essential roles in various biological processes. However, the mechanisms underlying CK transport as well as its function in plant growth and development are far from being fully elucidated. Here, we characterize the function of PURINE PERMEASE1 (OsPUP1) in rice (Oryza sativa L.). OsPUP1 was predominantly expressed in the root, particularly in vascular cells, and CK treatment can induce its expression. Subcellular localization analysis showed that OsPUP1 was predominantly localized to the endoplasmic reticulum (ER). Overexpression of OsPUP1 resulted in growth defect of various aerial tissues, including decreased leaf length, plant height, grain weight, panicle length, and grain number. Hormone profiling revealed that the CK content was decreased in the shoot of OsPUP1 -overexpressing seedling, but increased in the root, compared with the wild type. The CK content in the panicle was also decreased. Quantitative reverse transcription-PCR (qRT-PCR) analysis using several CK type-A response regulators (OsRRs) as the marker genes suggested that the CK response in the shoot of OsPUP1 -overexpressing seedling is decreased compared to the wild type when CKs are applied to the root. Genetic analysis revealed that BG3/OsPUP4, a putative plasma membrane-localized CK transporter, overcomes the function of OsPUP1. We hypothesize that OsPUP1 might be involved in importing CKs into ER to unload CKs from the vascular tissues by cell-to-cell transport. [ABSTRACT FROM AUTHOR]

To examine the extent to which heat stress during grain filling impacts on the development and yield of winter wheat (Triticum aestivum L.), a 3‐year field experiment was conducted on a loess soil with high water holding capacity in the North German Plain. Thirty‐two mostly European winter wheat cultivars were exposed to heat stress in a mobile foil tunnel with maximum air temperatures of 45.7, 45.4, and 47.2°C in 2015, 2016, and 2017, respectively. The 14‐day post‐anthesis heat stress treatment caused an average 57.3% grain yield reduction compared to a close‐by non‐stressed control. The proportion of green crop area after the heat stress phase varied from 7% to 98% in 2016 and from 37% to 94% in 2017. The green crop area percentage did not significantly correlate with grain yield, indicating that the delayed senescence of stay‐green phenotypes offers no yield advantage under terminal heat stress. The water soluble carbohydrate (WSC) concentration of the stems at crop maturity varied between 6 and 92 g/kg dry matter, showing that the genotypes differed in their efficiency at using the stem carbohydrate reserves for grain filling under heat stress. The stem WSC concentration correlated positively with the beginning of anthesis (r = 0.704; p <.001) but negatively with the grain yield (r = −0.431; p <.05). For heat tolerance breeding, the stem reserve strategy, i. e. the rapid and full exhaustion of the temporary carbohydrate storage therefore seems more promising than the stay‐green strategy. [ABSTRACT FROM AUTHOR]

In Algeria, drought affects grain weight and modified its biochemical composition. The present study was conducted to evaluate the effect of two water supplies (100% FC, 30% FC) on grain weight and composition of five genotypes of durum wheat (Triticum durum Desf.). We also examined the effects of shading of peduncle, spike and the entire plant and excision of awns, flag leaves and foliar system on grain weight, starch and amylose/amylopectin ratio. From this study, we found that grain weight was significantly reduced by the application of water deficit. However, this action is greatly related to genotype type. It is admitted that this trait is strongly conditioned by the grain filling process. The morphological characteristics of plants were implicated to grain weight elaboration. Among organs studied, the photosynthetic rate of spick and reserves remobilization from stem announced determinant in grain filling. We found also that starch content which is associated to amylose/amylopectin ratio is strongly related to grain weigh. Finally, grains weight variations were associated to starch content and mainly related to the water supply condition. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) yield enhancement is one of the prime objectives of plant breeders. Elucidation of the inheritance of grain weight, a key yield component trait, is of paramount importance for raising the yield thresholds in rice. In the present investigation, we employed Next-Generation Sequencing based QTL-seq approach to identify major genomic regions associated with grain weight using mapping populations derived from a cross between BPT5204 and MTU3626. QTL-seq analysis identified three grain weight quantitative trait loci (QTL) viz., qGW1 (35–40 Mb), qGW7 (10–18 Mb), and qGW8 (2–5 Mb) on chromosomes 1, 7 and 8, respectively and all are found to be novel. Further, qGW8 was confirmed through conventional QTL mapping in F2, F3 and BC1F2 populations and found to explain the phenotypic variance of 17.88%, 16.70% and 15.00%, respectively, indicating a major QTL for grain weight. Based on previous reports, two candidate genes in the qGW8 QTL were predicted i.e., LOC_Os08g01490 (Cytochrome P450), and LOC_Os08g01680 (WD domain, G-beta repeat domain containing protein) and through in silico analysis they were found to be highly expressed in reproductive organs during different stages of grain development. Here, we have demonstrated that QTL-seq is one of the rapid approaches to uncover novel QTLs controlling complex traits. The candidate genes identified in the present study undoubtedly enhance our understanding of the mechanism and inheritance of the grain weight. These candidate genes can be exploited for yield enhancement after confirmation through complementary studies. [ABSTRACT FROM AUTHOR]

Grain yield of wheat and its components are very sensitive to heat stress at the critical growth stages of anthesis and grain filling. We observed negative impacts of heat stress on biomass partitioning and grain growth in environment-controlled phytotron experiments over 4 years, and we quantified relationships between the stress and grain number and potential grain weight at anthesis and during grain filling using process-based heat stress routines. These relationships included reduced grain set under stress at anthesis and decreased potential grain weight under stress during early grain filling. Biomass partitioning to stems and spikes was modified under heat stress based on a source–sink relationship. The integration of our process-based stress routines into the original WheatGrow model significantly enhanced the predictions of the biomass dynamics of the stems and spikes, the grain yield, and the yield components under heat stress. Compared to the original model, the improved version decreased the simulation errors for grain yield, grain number, and grain weight by 73%, 48%, and 49%, respectively, in an evaluation using independent data under heat stress in the phytotron conditions. When tested with data obtained under field conditions, the improved model showed a good ability to reproduce the decreasing dynamics of grain yield and its components with increasing post-anthesis temperatures. Sensitivity analysis showed that the improved model was able to reproduce the responses to various observed heat-stress treatments. These improvements to the crop model will be of significant importance for assessing the effects on crop production of projected increases in heat-stress events under future climate scenarios. [ABSTRACT FROM AUTHOR]

Copyright of Terra Latinoamericana is the property of Sociedad Mexicana de la Ciencia del Suelo A.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background Grain weight is a grain yield component, which is an integrated index of grain length, width and thickness. They are controlled by a large number of quantitative trait loci (QTLs). Besides major QTLs, minor QTLs play an essential role. In our previous studies, QTL analysis for grain length and width was performed using a recombinant inbred line population derived from rice cross TQ/IRBB lines. Two major QTLs were detected, which were located in proximity to GS3 and GW5 that have been cloned. In the present study, QTLs for grain weight and shape were identified using rice populations that were homozygous at GS3 and GW5. Method Nine populations derived from the indica rice cross TQ/IRBB52 were used. An F10:11population named W1, consisting of 250 families and covering 16 segregating regions, was developed from one residual heterozygote (RH) in the F7generation of Teqing/IRBB52. Three near isogenic line (NIL)-F2 populations, ZH1, ZH2 and ZH3 that comprised 205, 239 and 234 plants, respectively, were derived from three RHs in F10:11. They segregated the target QTL region in an isogenic background. Two NIL populations, HY2 and HY3, were respectively produced from homozygous progeny of the ZH2 and ZH3 populations. Three other NIL-F2 populations, Z1, Z2 and Z3, were established using three RHs having smaller heterozygous segments. QTL analysis for 1000-grain weight (TGW), grain length (GL), grain width (GW), and length/width ratio (LWR) was conducted using QTL IciMapping and SAS procedure with GLM model. Result A total of 27 QTLs distributed on 12 chromosomes were identified. One QTL cluster, qTGW2/qGL2/qGW2 located in the terminal region of chromosome 2, were selected for further analysis. Two linked QTLs were separated in region Tw31911−RM266. qGL2 was located in Tw31911−Tw32437 and mainly controlled GL and GW. The effects were larger on GL than on GW and the allelic directions were opposite. qTGW2 was located in Tw35293−RM266 and affected TGW, GL and GW with the same allelic direction. Finally, qTGW2 was delimited within a 103-kb region flanked by Tw35293 and Tw35395. Conclusion qTGW2 with significant effects on TGW, GL and GW was validated and fine-mapped using NIL and NIL-F2 populations. These results provide a basis for map-based cloning of qTGW2 and utilization of qTGW2 in the breeding of high-yielding rice varieties.

During its reproductive phase, rice is susceptible to heat stress. Heat events will occur at all stages during the reproductive phase of rice as a result of global warming. Moreover, rice yield traits respond differently to heat stress during panicle initiation, flowering and grain filling. The reduction in the number of spikelets per panicle of heat-stressed plants is due to the attenuated differentiation of secondary branches and their attached florets as well as the promotion of their degradation during the panicle-initiation stage but is not affected by heat stress thereafter. Spikelet sterility as a result of heat stress is attributed not only to physiological abnormalities in the reproductive organs during the flowering stage but also to structural and morphological abnormalities in reproductive organs during the panicle-initiation stage. The reduced grain weight of heat-stressed plants is due to a reduction in nonstructural carbohydrates, undeveloped vascular bundles, and a reduction in glume size during the panicle-initiation stage, while a shortened grain-filling duration, reduced grain-filling rate, and decreased grain width contribute to reduced grain weight during the grain-filling stage. Thus, screening and breeding rice varieties that have comprehensive tolerance to heat stress at all time points during their reproductive stage may be possible to withstand unpredictable heat events in the future. The responses of yield traits to heat stress are regulated by phytohormone levels, which are determined by phytohormone homeostasis. Currently, the biosynthesis and transport of phytohormones are the key processes that determine phytohormone levels in and grain yield of rice under heat stress. Studies on phytohormone homeostatic responses are needed to further reveal the key processes that determine phytohormone levels under heat conditions.

A study was conducted to determine the optimum rates of N, P, K fertilizers on “IPB 9G” upland rice variety from March to July 2018 at the Sawah Baru Experimental Field of IPB University, West Java, Indonesia. Three paralel experiments were carried out in a randomized complete block design to test five fertilizing levels, i.e. 0, 50, 100, 150 and 200% of the reference rate. The reference rates of fertilizer application are 100% N = 200 kg Urea ha-1, 100% P = 100 kg SP36 ha-1, and 100% K = 100 kg KCl ha-1. The applied fertilizers were Urea (46% N), SP36 (36% P2O5) and KCl (60% K2O). Fertilizers were applied three times, 40% at planting, 30% at 4 WAP and the rest 30% at 8 WAP; 100% P and 100% K were applied at planting. Increasing N fertilizer from 0 to 200% of the reference rate increased plant height, dry weight biomass at heading and at harvest, number of productive tillers, harvest index, and grain weight per clump. P increased dry weight of the above ground biomass, whereas K fertilizer increased the leaf area, canopy dry weight, number of grain per panicle, panicle length, harvest index and grain weight per clump. The optimum rate of N and P were 107.09 kg Urea ha-1 and 63.3 kg P2O5 kg.ha-1, respectively, whereas the optimal rate for K fertilizer for “IPB 9G” could not be determined with this study.

This study was aimed to investigate the effect of thiamine (Th) foliar application on some morpho-physiological aspects in coriander and fenugreek. Three levels of Th (250, 500 and 750 ppm) plus control treatment (distilled water) were studied under controlled greenhouse conditions. All the levels of Th, in particular the concentration of 500 ppm, increased the vegetative growth of coriander. 1000-grain weight, contents of nitrogen and phosphorus, carotenoid and chlorophyll b contents were the highest at a concentration of 750 ppm. Fenugreek vegetative growth also responded positively to the application of Th especially at a concentration of 750 but also 500 ppm increased the content of leaf nitrogen, chlorophyll b, carotenoids, phenolics and antioxidant activity. Overall, the performance of coriander and fenugreek was improved by the application of Th foliar at all levels.

Abstract Background Rice is a major crop feeding the majority of the global population, and increasing its sink strength is one of the modes to alleviate the declining availability of food for the rapidly growing world population. We demonstrate a role for an important rice vacuolar invertase isoform, OsINV3, in sink strength determination. Results OsINV3 mutants showed shorter panicles with lighter and smaller grains, owing to a smaller cell size on the outer and inner surfaces of the palea and lemma as observed by scanning electron microscopy. Further, strong promoter::GUS expression was observed in the palea, lemma and the rachis branches in the young elongating panicles, which supported the role of OsINV3 in cell expansion and thus, in spikelet size and panicle length determination. Size of the spikelet was found to directly influence the grain weight, which was confirmed by the lack of differences in weights of hulled grain for differently segregated alleles in the heterozygous lines. Assessment of field grown mutants not only revealed a drastic reduction in the percentage of ripened grain, 1000-grain weight and final yield, but also significantly reduced partitioning of assimilates to the panicles, whereby the total dry weight remained unaffected. Determination of the non-structural carbohydrate contents revealed a lower hexose-to-sucrose ratio in the panicles of the mutants from panicle initiation to 10 days after heading, a stage that identifies as the critical pre-storage phase of grain filling, whereas the starch contents were not affected. In addition, strong promoter::GUS expression was observed in the dorsal end of ovary during the pre-storage phase until 6 days after flowering, highlighting a function for OsINV3 in monitoring the initial grain filling stage. Conclusions OsINV3 was found to regulate spikelet size by playing a key role in cell expansion, driving the movement of assimilates for grain filling by modulating the hexose-to-sucrose ratio, contributing in grain weight determination and thus, the grain yield.

The simple methods used for indirect biomass determination are recognized as potentially important tools for crop growth prediction. The normalized difference vegetation index (NDVI) is widely used for assessing crop biomass, yield, photosynthesis, and nitrogen management. Aims of this study were to determine the variation in NDVI values and relationship of the NDVI with the most significant agronomic properties in the elite genotypes of two-rowed winter barley. The experiment included elite two-rowed winter barley genotypes and was carried out in two growing seasons. NDVI were measured at mid-anthesis, while grain yield and grain yield components were determined from combine harvested samples at maturity. Results from this study showed that the influence of genotype was mainly responsible for variation in most studied traits. Grain yield of two-rowed barley cultivars was more related to high grain number per unit area than to grain weight. NDVI values at anthesis in both growing seasons were positively associated with grain yield (R2 = 0.444 and R2 = 0.386), grain number (R2 = 0.387 and R2 = 0.507) and plant height (R2 = 0.352 and R2 = 0.364), while relationship with grain weight was not significant. Significant genotypic variation for NDVI values and the presence of significant positive relationship with grain yield and grain number indicated that NDVI measurement at anthesis could be efficiently used for indirect identification of productive two-rowed winter barley genotypes.

Abstract Background There is an urgent need to increase global crop production. Identifying and combining specific genes controlling distinct biological processes holds the potential to enhance crop yields. Transcriptomics is a powerful tool to gain insights into the complex gene regulatory networks that underlie such traits, but relies on the availability of a high-quality reference sequence and accurate gene models. Previously, we identified a grain weight QTL on wheat chromosome 5A (5A QTL) which acts during early grain development to increase grain length through cell expansion in the pericarp. In this study, we performed RNA-sequencing on near isogenic lines (NILs) segregating for the 5A QTL and used the latest gene models to identify differentially regulated genes and pathways that potentially influence pericarp cell size and grain weight in wheat. Results We sampled grains at 4 and 8 days post anthesis and found that genes associated with metabolism, biosynthesis, proteolysis and the defence response are upregulated during this stage of grain development in both NILs. We identified a specific set of 112 transcripts differentially expressed (DE) between 5A NILs at either time point, including eight potential candidates for the causal 5A gene and its downstream targets. The 112 DE transcripts had functional annotations including non-coding RNA, transposon-associated, cell-cycle control, ubiquitin-related, heat-shock, transcription and histone-related. Many of the genes identified belong to families that have been previously associated with seed/grain development in other species. Notably, we identified DE transcripts at almost all steps of the pathway associated with ubiquitin-mediated protein degradation. In the promoters of a subset of DE transcripts we identified enrichment of binding sites associated with C2H2, MYB/SANT, YABBY, AT-HOOK and Trihelix transcription factor families. Conclusions In this study, we identified DE transcripts with a diverse range of predicted biological functions, reflecting the complex nature of the pathways that control early grain development. Few of these are the direct orthologues of grain size genes in other species and none have been previously characterised in wheat. Further functional characterisation of these candidates and how they interact will provide novel insights into the control of grain size in cereals.

Grain weight and size are important traits determining grain yield and influencing grain quality in rice. In a previous study, a quantitative trait locus controlling thousand-grain weight (TGW) in rice, qTGW10-20.8, was mapped in a 70.7 kb region on chromosome 10. Validation of the candidate gene for qTGW10-20.8, OsMADS56 encoding a MADS-box transcription factor, was performed in this study. In a near-isogenic line (NIL) population segregated only at the OsMADS56 locus, NILs carrying the OsMADS56 allele of IRBB52 were 1.9% and 2.9% lower in TGW than NILs carrying the OsMADS56 allele of Teqing in 2018 and 2020, respectively. Using OsMADS56 knock-out mutants and overexpression transgenic plants, OsMADS56 was validated as the causal gene for qTGW10-20.8. Compared with the recipients, the TGW of the knock-out mutants was reduced by 6.0–15.0%. In these populations, decreased grain weight and size were associated with a reduction in the expression of OsMADS56. In transgenic populations of OsMADS56 driven by a strong constitutive promoter, grain weight and size of the positive plants were significantly higher than those of the negative plants. Haplotype analysis showed that the Teqing-type allele of OsMADS56 is the major type presented in cultivated rice and used in variety improvement. Cloning of OsMADS56 provides a new gene resource to improve grain weight and size through molecular design breeding.

In a changing climate, extreme weather events such as heatwaves will be more frequent and could affect grain weight and the quality of crops such as wheat, one of the most significant crops in terms of global food security. In this work, we characterized the response of Triticum turgidum L. spp. durum wheat to short-term heat stress (HS) treatment at transcriptomic and physiological levels during early grain filling in glasshouse experiments. We found a significant reduction in grain weight (23.9%) and grain dimensions from HS treatment. Grain quality was also affected, showing a decrease in starch content (20.8%), in addition to increments in grain protein levels (14.6%), with respect to the control condition. Moreover, RNA-seq analysis of durum wheat grains allowed us to identify 1590 differentially expressed genes related to photosynthesis, response to heat, and carbohydrate metabolic process. A gene regulatory network analysis of HS-responsive genes uncovered novel transcription factors (TFs) controlling the expression of genes involved in abiotic stress response and grain quality, such as a member of the DOF family predicted to regulate glycogen and starch biosynthetic processes in response to HS in grains. In summary, our results provide new insights into the extensive transcriptome reprogramming that occurs during short-term HS in durum wheat grains.

The heterotrimeric G-protein mediates growth and development by perceiving and transmitting signals in multiple organisms. Alternative splicing (AS), a vital process for regulating gene expression at the post-transcriptional level, plays a significant role in plant adaptation and evolution. Here, we identified five splicing variants of Gγ subunit gene TaGS3 (TaGS3.1 to TaGS3.5), which showed expression divergence during wheat polyploidization, and differential function in grain weight and size determination. TaGS3.1 overexpression significantly reduced grain weight by 5.89% and grain length by 5.04%, while TaGS3.2–3.4 overexpression did not significantly alter grain size compared to wild type. Overexpressing TaGS3.5 significantly increased the grain weight by 5.70% and grain length by 4.30%. Biochemical assays revealed that TaGS3 isoforms (TaGS3.1–3.4) with an intact OSR domain interact with WGB1 to form active Gβγ heterodimers that further interact with WGA1 to form inactive Gαβγ heterotrimers. Truncated isoforms TaGS3.2–3.4 , which lack the C-terminal Cys-rich region but have enhanced binding affinity to WGB1, antagonistically compete with TaGS3.1 to bind WGB1, while TaGS3.5 with an incomplete OSR domain does not interact with WGB1. Taking these observations together, we proposed that TaGS3 differentially regulates grain size via AS, providing a strategy by which the grain size is fine-tuned and regulated at the post-transcriptional level.

Monogalactosyl diacylglycerol (MGDG), the main component of the plastid membrane, is essential for chloroplast photosynthesis; however, little information is available about the function of MGDG synthases gene (TaMGD) in wheat grain. In this manuscript, three homologous genes were identified in wheat grain, and their functions were investigated by gene silencing and overexpression techniques. Three TaMGD homologous genes, TaMGD-6A , -6B , and -6D , located on chromosome 6A, 6B, and 6D, respectively, were isolated from common wheat. The transcription of TaMGD was detected in stems, roots, leaves and grains, and high levels of gene transcripts were detected in stems and leaves. Silencing of TaMGD in common wheat spikes resulted in a decrease in grain weight and starch content, and proteomic analysis showed that the differentially expressed proteins mainly included carbohydrate metabolism- and nucleic acid-related proteins. In comparison with wild-type, transgenic rice plants overexpressing TaMGD-6A and -6D showed an increase in thousand kernel weight, as well as an increase in the expression level of genes related to starch biosynthesis, whereas transgenic rice plants overexpressing TaMGD-6B showed increased grain yield and grain number per spike. The results of gene silencing and overexpression indicated that TaMGD plays an important role in wheat grain weight, which might be associated with carbohydrate metabolism. Hence, this study provides new insights regarding the role of TaMGD in wheat grain characteristics. • TaMGD from wheat encodes monogalactosyl diacylglycerol synthase localised in plastid. • Silencing TaMGD in wheat spike resulted in decreased grain starch content. • Overexpression of TaMGD resulted in increased grain yield in transgenic rice plant. • TaMGD mainly affects grain weight by affecting carbohydrate metabolism. [ABSTRACT FROM AUTHOR]

In crop studies, shading is a common approach for reducing source activity (i.e. assimilates produced by photosynthesis); however, if source reduction is not directly proportional to the degree of light attenuation, estimations could be flawed. We analysed the effects of shading at three levels on light transmittance, air and canopy temperatures, and actual photosynthetic activity at different times of day, and on grain weight in a modern genotype of bread wheat (Triticum aestivum L.). The treatments were imposed 10 days after anthesis and comprised three levels of shading with meshes: 80%, 50% and 10% transmittance during midday. The decrease in midday photosynthetic activity (electron transport rate, ETR; and CO2 assimilation, An) in the shading treatments compared with control plants did not fit a 1 : 1 relationship with light transmittance of the meshes; for example, the reduction in ETR and An was <50% under the mesh with 50% light transmittance. The decrease in light transmittance and photosynthesis caused by the meshes was higher during the morning and afternoon than midday. In the grain-filling period, midday ETR showed a progressive, age-dependent decrease in control plants compared with shading treatments. Initial differences in photosynthetic activity between treatments were attenuated throughout the grain-filling period. The diurnal course of air temperature showed a progressive decrease from control to shade treatments, mainly during midday. This pattern was confirmed by infrared thermometry of canopy temperature, with severe shade showing the lowest temperature. Greenness measurements at 19 days after anthesis showed delayed senescence in shaded plants, possibly due to the decrease in temperature under shade. Grain weight per ear was reduced in shading treatments (mainly with 50% and 10% light transmittance). The decrease in grain weight per ear plotted against the decrease in photosynthesis (evaluated through ETR or An) did not fit a 1 : 1 relationship. This could be explained in part by an observed increase in dry matter retranslocation from the stem. In summary, estimations of source reduction on the basis of light attenuation could be biased, because the photosynthesis decrease is less than proportional, and photosynthesis differences are attenuated throughout grain filling. Understanding source–sink relations is important for improving grain yield in wheat. Estimations of reductions in source (i.e. assimilates produced by photosynthesis) on the basis of light attenuation (shading) could be flawed due to methodological biases. In this work we analysed several physiological aspects (e.g. photosynthesis) of source manipulation by meshes. [ABSTRACT FROM AUTHOR]

Thousand grain weight (TGW) is one of the three crucial determinants of wheat (Triticum aestivum) grain yield. The identification of functional genes and development of closely linked markers are urgently needed for wheat yield improvements. In this study, quantitative trait locus (QTL) mapping for TGW was carried out using one RIL population in four environments. A total of 8 QTL controlling TGW were detected across four chromosomes. Of them, QGW4B.4-17 was confirmed as a major and stable QTL for TGW increases of 2.19–3.06 g and high PVE of 22.5–36.3% in three environments. It was located in an interval (Rht1-TaGW-4B) of 2 Mb in physical distance that contains the Rht1 locus. Three high-confidence (HC) genes were predicted as potential candidates according to their annotated functions and expression profiles. Furthermore, a cleaved amplified polymorphic sequence (CAPS) marker, TaGW-4B, was developed and verified in a panel of 205 wheat cultivars and showed a highly significant correlation with TGW, demonstrating high value for efficient marker-assisted selection. The study provided a basis for cloning the functional genes underlying the QTL and a practical and accurate marker for molecular breeding. [ABSTRACT FROM AUTHOR]

The results of research on the influence of biologics based on rhizosphere microorganisms on the yield of spring wheat grain on different backgrounds of mineral nutrition on sod-podzolic light-loamy soil are presented. It was found that inoculation of spring wheat seeds with biologics provides an increase in grain yield by 1.2–1.3 times, while nitrogen fertilizer at doses of N45 and N90 provide increases by two and 3.5 times, respectively. The collection of raw protein due to the improvement of nitrogen nutrition increases with the introduction of N45 by two times and with N90 by 3.6 times; that with the use of biological products is by 25–45%. The vast majority of the nitrogen consumed accumulated in the grain, while less in the straw. The grain of spring wheat, while improving the supply of nitrogen to plants during the growing season, contained 76–81% of thiselement from the accumulated harvest. It is concluded that the use of biologics on sod-podzolic light-loamy soil has a positive effect on the growth of spring wheat grain mass, improves the quality of products, and increases the payback of mineral fertilizers by increasing the yield. [ABSTRACT FROM AUTHOR]

Maize grain filling (GF) and grain weight (GW) are closely associated with grain yield. In our study, the ZmARM4 locus affecting GF and GW was identified using a reverse genetics screen of UniformMutator (Mu). First, MutatorDR‐flanking sequence (MuDRFs) was isolated from the mutant by the MuDR‐amplified fragment length polymorphism method, and it was verified by cosegregation (between MuDRFs and phenotype) and linkage analyses. Second, the target gene of the MuDRFs was found to encode the Armadillo domain of the repeat protein gene families and has high expression in the GF stage. Third, association mapping between SNPs in the ZmARM4 region and the GW of 489 maize lines indicated that ZmARM4 is a functional gene that is closely related to GW. Moreover, bioinformatics analysis suggested that ZmARM4 may be relevant for the activity of sucrose transport or the number of cell divisions in endosperm cells. Therefore, ZmARM4 may be used as an important locus for maize GW in molecular breeding. [ABSTRACT FROM AUTHOR]

Summary: Argonaute (AGO) proteins and small RNAs (sRNAs) are core components of the RNA‐induced silencing complex (RISC). It has been reported that miRNAs regulate plant height and grain size in rice, but which AGO is involved in grain size regulation remains unclear. Here, we report that enhanced expression of OsAGO17, a putative AGO protein, could improve grain size and weight and promote stem development in rice. Cytological evidence showed that these effects are mainly caused by alteration of cell elongation. Expression analyses showed that OsAGO17 was highly expressed in young panicles and nodes, which was consistent with the expression pattern of OsmiR397b. SRNA sequencing, stem‐loop RT‐PCR and sRNA blotting showed that the expression of OsmiR397b was reduced in ago17 and enhanced in the OsAGO17 OE lines. Four OsmiR397b target laccase (LAC) genes showed complementary expression patterns with OsAGO17 and OsmiR397b. Combined with the results of immunoprecipitation (IP) analysis, we suggested that OsAGO17 formed an RISC with OsmiR397b and affected rice development by suppression of LAC expression. In conclusion, OsAGO17 might be a critical protein in the sRNA pathway and positively regulates grain size and weight in rice. [ABSTRACT FROM AUTHOR]

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty‐five spring durum genotypes carrying all known allele variants at Ppd‐1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd‐B1a) and the latest (Ppd‐A1b/Ppd‐B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn‐sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring‐sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd‐B1a and GS105/Ppd‐B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes. [ABSTRACT FROM AUTHOR]

This paper aimed at estimating the yield extract of some Romanian winter barley genotypes (six and two-row varieties and breeding lines), using different growing conditions (nitrogen fertilizer rate). All the experiments were performed at NARDI Fundulea and during the 2013-2016 period, winter six-row barley and two-row barley genotypes were tested under different N rates (NR0, NR1 and NR2). The obtained results were used to determine yield extract of each genotype (using Bishop's formula), perform the variance analysis, and asses the correlations of the studied parameters (grain weight, protein content, and yield extract). ANOVA showed a genotype and N fertilizer rate significantly influenced on grain weight, protein content, and yield extract for both six and two-row genotypes and for all nine tested conditions. For all winter six-row barley quality parameters under two years an insignificant influence of genotype x N rate interaction on these was showed while winter two-row barley revealed a different behavior. This source of variation was significant only one experimental year for protein content, two years for yield extract and one year for grain weight. The yield extract, grain weight, and protein content were assessed separately among winter six-row and two-row barley. Under all N rate (except NR2 for winter six-row barley and NR0 for winter two-row barley) there was a significant negative correlation between yield extract and protein content (from -0.54 to -0.89 and -0.61 to -0.89 respectively). The same comparison showed that the grain weight was not correlated with protein content for winter two-row barley under any of the experimental year conditions; while this was positive in two years for winter six-row barley (from 0.42 to 0.77). During the 2013-2016 period, the yearly average yield extract has varied due to change of the protein content and grain weight, namely was noticed an increasing tendency from NR0 to NR1 and a decrease one from NR1 to NR2. [ABSTRACT FROM AUTHOR]

Seed filling in wheat is controlled by the availability of substrate (source strength), the capacity of the organs to utilize it for seed growth (sink strength). The aim of this research was to study source-sink relations in wheat, through seed weight and grain number in new and old wheat cultivars. The experiment was performed at Moghan College of Agriculture and Natural Resources, Research Farm (University of Mohaghegh Ardabili) during 2010-2011 growing season. The plant materials (81 wheat cultivars) were evaluated using a simple lattice design with two replications under well-watered condition. The results showed that there were significant differences for measured agronomic and physiologic traits among wheat cultivars tested. Overall, new wheat cultivars showed high values of seed yield as compared with the old ones. This trend was also observed in the cases of harvest index (HI) and grain number per square meter. There were no significant differences in biological yield and 1000-grain weight between old and new cultivars. Spike dry weight measured at anthesis and physiologic maturity and also partitioning photoassimilates to the spike during anthesis-physiologic maturity phases increased more in new cultivars than old ones. Increased grain number in new wheat cultivars and the lack of significant changes in 1000-seed weight suggests that seed yields of the cultivars used under the condition tested are controlled more by sink than source strength. Under conditions tested, it seems that increased grain number, either in plant level or in square meter, might be considered as a way to assess increased seed yield.

Grain weight and size are among the main traits used for characterizing a barley variety in order to recommend it for malt industry. Moreover, the first evaluated trait to know the yield destination is the grain weight which is determined by the grain length and width. In the malt industry, the grain size is an important characteristic having into account the fact that the potential extract is proportional to the size of the grain. This trait depends on genotypes, environment and crop technology, as well as on the interactions between these factors. The objective of this paper has been the assessment of the grain weight (expressed through the thousand grain weight - TGW) and the grain size fractions (2.8 mm, 2.5 mm, and 2.2 mm), as well as the yield potential for the Romanian winter barley genotypes in order to establish further usage. In this respect, twenty-five winter barley genotypes created at National Agriculture Research and Development Institute Fundulea were investigated in 2017-2018 under two different sowing densities (350 grains/m2 and 500 grains/m2). Barley samples have been analyzed for grain weight using Contador (electronic seeds counter) and screening machine Sortimat for sieving fractions at different grain size (2.8 mm, 2.5 mm, and 2.2 mm). Obtained data has been statistically analyzed by ANOVA. Analyses of variance revealed a significant variation of TGW and grain size between genotype and sowing density. According to the 20th European Brewery Convention (EBC) of evaluation malting barley varieties, the requested minimum value of TGW for malt industry is 42 g and more than 80% of grains have to remain on the sieves of 2.8 mm and 2.5 mm. Under low sowing density (350 grains/m2) the values of TGW ranged between 48.1 and 55 grams, while for the second sowing density (500 grains/m2) the values ranged between 41.4 and 50.2 grams. The grain size fraction of 2.8 mm showed a better proportion value (97.2%) under low sowing density comparing with the value of the same grain size fraction obtained under high sowing density (92.8%). All tested winter barley genotypes registered an increased yield under low sowing density (5804 - 9304 kg/ha) comparing with the yield obtained at high sowing density (4074 - 6978 kg/ha). [ABSTRACT FROM AUTHOR]

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Main conclusion: Totally, 48 loci responsible for six spike-related traits were identified in wheat, and a major locus QGl-4A for grain length was mapped and validated for marker-assisted selection in breeding. Wheat yield is determined by the number of spikes, number of grains per spike (GN), and one-thousand kernel weight (TKW), among which GN and TKW are greatly related to the spike development and thus the spike-related traits, including spike length (SL), number of spikelet per spike (SN), grain length (GL) and grain width (GW). To identify the key loci governing the spike-related traits (SL, SN, GN, TKW, GL and GW), we conducted the quantitative trait loci (QTL) analysis combined with wheat 660K SNP chip and Kompetitive allele-specific PCR (KASP) assay, using the F2 and F2:3 populations derived from Luohan6 (LH6) with big spike and grain and Zhengmai366 with small spike and grain, and identified a total of 48 QTLs on 18 chromosomes. Moreover, a major stable QTL for GL on chromosome 4A, designated as QGl-4A, was mapped into a 0.37 cM interval between KASP markers Xib4A-10 and Xib4A-12, corresponding to 20 Mb physical region in the Chinese Spring genome. This QTL explained 17.30% and 5.12% of the phenotypic variation for GL in the F2 and F2:3 populations. Further association analysis of flanking markers Xib4A-10 and Xib4A-12 in 192 wheat varieties showed that these two markers could be used for marker-assisted selection in breeding. These results provide valuable information for map-based cloning of the target genes involved in the regulation of spike-related traits in common wheat. [ABSTRACT FROM AUTHOR]

Key message: The quantitative trait loci (QTLs) for grain morphological traits were identified via nested association mapping and validated in a natural wheat population via haplotype analysis. Grain weight, one of the three most important components of crop yield, is largely determined by grain morphological traits. Dissecting the genetic bases of grain morphology could facilitate the improvement of grain weight and yield production. In this study, four wheat recombinant inbred line populations constructed by crossing the modern variety Yanzhan 1 with three semi-wild wheat varieties (i.e., Chayazheda, Yutiandaomai, and Yunnanxiaomai from Xinjiang, Tibet, and Yunnan, respectively) and one exotic accession Hussar from Great Britain were investigated for grain weight and eight morphological traits in seven environments. Eighty-eight QTLs for all measured traits were totally identified through nested association mapping utilizing 14,643 high-quality polymorphic single nucleotide polymorphism (SNP) markers generated by 90 K SNP array. Among them, 64 (72.7%) QTLs have the most favorable alleles donated by semi-wild wheat varieties. For 14 QTL clusters affecting at least two grain morphological traits, nine QTL clusters were located in similar position with known genes/QTL, and the other five were novel. Three important novel QTLs (i.e., qTGW-1B.1, qTGW-1B.2, and qTGW-1A.1) were further validated in a natural wheat population via haplotype analysis. The favorable haplotypes for these three QTLs might be used in marker-assisted selection for the improvement of wheat yield by modifying morphological traits. [ABSTRACT FROM AUTHOR]

Autotrophic plants have evolved distinctive mechanisms for maintaining a range of homeostatic states for sugars. The on/off switch of reversible gene expression by sugar starvation/provision represents one of the major mechanisms by which sugar levels are maintained, but the details remain unclear. α-Amylase (αAmy) is the key enzyme for hydrolyzing starch into sugars for plant growth, and it is induced by sugar starvation and repressed by sugar provision. αAmy can also be induced by various other stresses, but the physiological significance is unclear. Here, we reveal that the on/off switch of αAmy expression is regulated by 2 MYB transcription factors competing for the same promoter element. MYBS1 promotes αAmy expression under sugar starvation, whereas MYBS2 represses it. Sugar starvation promotes nuclear import of MYBS1 and nuclear export of MYBS2, whereas sugar provision has the opposite effects. Phosphorylation of MYBS2 at distinct serine residues plays important roles in regulating its sugar-dependent nucleocytoplasmic shuttling and maintenance in cytoplasm by 14-3-3 proteins. Moreover, dehydration, heat, and osmotic stress repress MYBS2 expression, thereby inducing αAmy3. Importantly, activation of αAmy3 and suppression of MYBS2 enhances plant growth, stress tolerance, and total grain weight per plant in rice. Our findings reveal insights into a unique regulatory mechanism for an on/off switch of reversible gene expression in maintaining sugar homeostatic states, which tightly regulates plant growth and development, and also highlight MYBS2 and αAmy3 as potential targets for crop improvement. [ABSTRACT FROM AUTHOR]

Summary: Starch is the most important form of energy storage in cereal crops. Many key enzymes involved in starch biosynthesis have been identified. However, the molecular mechanisms underlying the regulation of starch biosynthesis are largely unknown. In this study, we isolated a novel floury endosperm rice (Oryza sativa) mutant flo16 with defective starch grain (SG) formation. The amylose content and amylopectin structure were both altered in the flo16 mutant. Map‐based cloning and complementation tests demonstrated that FLO16 encodes a NAD‐dependent cytosolic malate dehydrogenase (CMDH). The ATP contents were decreased in the mutant, resulting in significant reductions in the activity of starch synthesis‐related enzymes. Our results indicated that FLO16 plays a critical role in redox homeostasis that is important for compound SG formation and subsequent starch biosynthesis in rice endosperm. Overexpression of FLO16 significantly improved grain weight, suggesting a possible application of FLO16 in rice breeding. These findings provide a novel insight into the regulation of starch synthesis and seed development in rice. [ABSTRACT FROM AUTHOR]

This study was conducted in order to assess the stomata resistance response, transpiration volume for canopy temperature regulation and leaf rolling under drought stress condition for some new hybrids of maize. The experiment was laid out as a factorial design based on randomized complete block with three replications, in 2015 and 2016, at Seed and Plant Improvement Institute, Karaj. Three Irrigation levels include Irrigation after 60, 90 and120 mm cumulative evaporation from evaporation pan class A, and four hybrids include KSC 703, KSC704, KSC705 and KSC706 were considered as the factors. The lower stomata resistance and canopy temperature were obtained in KSC 706 which had no leaf rolling in vegetative stage even under heat condition at noon. Grain weight was lower in KSC 706 in comparisons to other hybrids under mid and severe drought stress. The maximum and minimum of grain yield were obtained under normal irrigation and severe drought stress condition with average 7.64 and 3.34 ton/ha respectively. There were no significant difference in grain yield of different hybrids, but the highest grain moisture was obtained from KSC 706 with average 17.61%. Based on this experiment, KSC 706 may be sensitive to drought stress due to opening of the stomata and wasting moisture in environment around root zone via transpiration, so it is not recommend for the areas where there are limitation in irrigation water. [ABSTRACT FROM AUTHOR]

Wheat is a crop of vital importance for food security. In contrast to the accumulated knowledge for yield determination, the effect of variations in the source/sink (S/S) ratio on grain quality, and its interaction with the genotype and fertilization level, have received little attention. This work aimed to analyze the incidence of S/S ratio changes during post-flowering on grain weight and commercial quality in bread wheat genotypes with contrasting baking aptitude, as well as to evaluate its interaction with early nitrogen-sulfur fertilization. It is hypothesized that modern wheat genotypes bred for high-yield and contrasting baking aptitudes differ in their responses to variations in the availability of assimilates during post-flowering. Rainfed field trials were carried out in the Humid Pampas of Argentina during two years. Six wheat genotypes belonging to different quality groups were used, to which manipulative S/S treatments in post-flowering (shading, defoliation, thinning, trimming) and different levels of nitrogen-sulfur fertilization were applied. Regressions between S/S ratio (growth per grain) and grain variables (grain weight, protein content per grain, protein concentration, and test weight) were analyzed. Grain weight responses ranged from − 42% to + 31% relative to control compared to variations in S/S ratio from − 81% to + 56%, varying with the year and genotype. Relative changes of grain weight and S/S ratio were linearly associated, showing differences in stability (slope range: 0.29–0.80) among genotypes (the lower the slope, the greater the stability). Protein content per grain increased linearly with increases in the S/S relationship only for fertilized crops with N and S. As expected, protein concentration decreased when the S/S ratio increased, while test weight was the opposite. Importantly, responses varied among genotypes and fertilization levels, regardless of baking quality group. Grain weight to S/S ratio after flowering relationships differed between bread wheat genotypes, even within the same quality group, while protein content stability did not differ significantly. Therefore, for the conditions of this study in high-yielding environments in the Humid Pampas, the different protein concentration responses were due to genotypic differences in grain weight stability against variations in assimilates availability during grain filling. Nitrogen-sulfur fertilization early at the crop cycle did not modify the grain weight responses to variations in the S/S ratio, although it increased their influence on the commercial quality parameters. These findings are relevant to genetic improvement for high yield that can increase the co-limitation by source and sinks, and the occurrence of farm adversities that restrict the source capacity during post-flowering. • The impact of source/sink ratio on wheat grain weight and their quality were assessed. • Genotypes differed in their grain weight stability to source/sink ratio changes. • Test weight was more stable for genotypes with the best baking quality. • N-S fertilization increased responses of protein percentage and test weight to source/sink ratio. [ABSTRACT FROM AUTHOR]

Cultivation of malting barley is particularly challenging as the requirements of growers, for high yield, and that of the brewing industry, seeking a specific quality criteria, must be met simultaneously. Furthermore, significant genotypic and environmental variations in grain yield and quality properties may occur. To investigate the relationships between grain yield and quality parameters of spring malting barley, a 2-year experiment was carried out in order to characterise the genotypic and year effects on grain yield, quality properties, and yield components of 23 high-yielding varieties of spring malting barley under optimal nitrogen (N) fertilisation. Compared to the grain quality properties of the grain protein content and the grain retention fraction of grain size >2.5 mm, less genotypic and environmental variation in grain yield was observed. Grain yield was closely related to spikes per m2, suggesting the importance of tiller formation and establishment as a decisive factor influencing malting barley yields. A major interactive effect of genotypes and year on grain size was observed. Regarding weather effects, the global radiation intensity during the post-anthesis phase was the major factor affecting the final grain size in this study. Grain protein content was primarily dependent on the year effect, suggesting that optimal N fertilisation levels must vary between years to ensure the correct protein content required for the needs of the brewing industry is met. Therefore, we recommend further development strategies addressing N fertilisation and soil N mineralisation to optimise the production of spring malting barley.

This article is a Commentary on Calderini et al. (2021), 230: 629‐640. [ABSTRACT FROM AUTHOR]

Glutaredoxins (Grxs) are a ubiquitous group of oxidoreductase enzymes that are important in plant growth and development; however, the functions of rice Grxs have not been fully elucidated. In this paper, we showed that one of the Grxs, encoded by OsGrxC2.2, exhibited Grx activity. Furthermore, we demonstrated that OsGrxC2.2 was able to regulate embryo development during embryogenesis. Transgenic rice lines overexpressing OsGrxC2.2 unexpectedly exhibited degenerate embryos as well as embryoless seeds. Our data indicated that the embryonic abnormalities occurred at an early stage during embryogenesis. We found that the expression of several endodermal layer marker genes for embryo development, such as OSH1 (apical region marker), OsSCR (L2 ground tissue marker), and OsPNH1 (L3 vascular tissue marker), were significantly decreased in the OsGrxC2.2-overexpressed transgenic rice lines. In contrast, the transcript levels of the majority of protodermal layer markers, including HAZ1, ROC2, ROC3, and RAmy1A, and the shoot apical meristem marker HB, showed little change between the wild-type (WT) and OsGrxC2.2-overexpressing embryos. Surprisingly, the seed weight of the overexpressed transgenic rice was remarkably increased in comparison to that of the WT. These results indicate that the overexpression of OsGrxC2.2 interferes with the normal embryogenesis of rice embryos and leads to increased grain weight. To the best of our knowledge, this is the first report that OsGrxC2.2 is a rice embryo development-associated gene.

Background Thousand grain weight is a key component of grain yield in rice, and a trait closely related to grain length (GL) and grain width (GW) that are important traits for grain quality. Causal genes for 16 quantitative trait loci (QTL) affecting these traits have been cloned, but more QTL remain to be characterized for establishing a genetic regulating network. A QTL controlling grain size in rice, qGS10, was previously mapped in the interval RM6100–RM228 on chromosome 10. This study aimed to delimitate this QTL to a more precise location. Method A total of 12 populations were used. The ZC9 population comprised 203 S1:2 families derived from a residual heterozygous (RH) plant in the F9 generation of the indica rice cross Teqing (TQ)/IRBB52, segregating the upper region of RM6100–RM228 and three more regions on chromosomes 1, 9, and 11. The Ti52-1 population comprised 171 S1 plants derived from one RH plant in F7 of TQ/IRBB52, segregating a single interval that was in the lower portion of RM6100–RM228. The other ten populations were all derived from Ti52-1, including five S1 populations with sequential segregating regions covering the target region and five near isogenic line (NIL) populations maintaining the same segregating pattern. QTL analysis for 1,000-grain weight, GL, and GW was performed using QTL IciMapping and SAS procedure GLM. Result Three QTL were separated in the original qGS10 region. The qGL10.1 was located in the upper region RM6704–RM3773, shown to affect GL only. The qGS10.1 was located within a 207.1-kb interval flanked by InDel markers Te20811 and Te21018, having a stable and relatively high effect on all the three traits analyzed. The qGS10.2 was located within a 1.2-Mb interval flanked by simple sequence repeat markers RM3123 and RM6673. This QTL also affected all the three traits but the effect was inconsistent across different experiments. QTL for grain size were also detected in all the other three segregating regions. Conclusion Three QTL for grain size that were tightly linked on the long arm of chromosome 10 of rice were separated using NIL populations with sequential segregating regions. One of them, qGS10.1, had a stable and relatively high effect on grain weight, GL, and GW, providing a good candidate for gene cloning. Another QTL, qGS10.2, had a significant effect on all the three traits but the effect was inconsistent across different experiments, providing an example of genotype-by-environmental interaction.

Grain size is a key component of grain yield in cereals. It is a complex quantitative trait controlled by multiple genes. Grain size is determined via several factors in different plant development stages, beginning with early tillering, spikelet formation, and assimilates accumulation during the pre-anthesis phase, up to grain filling and maturation. Understanding the genetic and molecular mechanisms that control grain size is a prerequisite for improving grain yield potential. The last decade has brought significant progress in genomic studies of grain size control. Several genes underlying grain size and weight were identified and characterized in rice, which is a model plant for cereal crops. A molecular function analysis revealed most genes are involved in different cell signaling pathways, including phytohormone signaling, transcriptional regulation, ubiquitin-proteasome pathway, and other physiological processes. Compared to rice, the genetic background of grain size in other important cereal crops, such as wheat and barley, remains largely unexplored. However, the high level of conservation of genomic structure and sequences between closely related cereal crops should facilitate the identification of functional orthologs in other species. This review provides a comprehensive overview of the genetic and molecular bases of grain size and weight in wheat, barley, and rice, focusing on the latest discoveries in the field. We also present possibly the most updated list of experimentally validated genes that have a strong effect on grain size and discuss their molecular function.

Starch is the most abundant substance in wheat (Triticum aestivum L.) endosperm and provides the major carbohydrate energy for human daily life. Starch synthesis-related (SSR) genes are believed to be spatiotemporally specific, but their transcriptional regulation remains unclear in wheat. Here, we investigate the role of the basic helix-loop-helix (bHLH) transcription factor TabHLH95 in starch synthesis. TabHLH95 is preferentially expressed in the developing grains in wheat and encodes a nucleus localized protein without autoactivation activity. The Tabhlh95 knockout mutants display smaller grain size and less starch content than wild type, whereas overexpression of TabHLH95 enhances starch accumulation and significantly improves thousand grain weight. Transcriptome analysis reveals that the expression of multiple SSR genes is significantly reduced in the Tabhlh95 mutants. TabHLH95 binds to the promoters of ADP-glucose pyrophosphorylase large subunit 1 (AGPL1-1D/-1B), AGPL2-5D, and isoamylase (ISA1-7D) and enhances their transcription. Intriguingly, TabHLH95 interacts with the nuclear factor Y (NF-Y) family transcription factor TaNF-YB1, thereby synergistically regulating starch synthesis. These results suggest that the TabHLH95-TaNF-YB1 complex positively modulates starch synthesis and grain weight by regulating the expression of a subset of SSR genes, thus providing a good potential approach for genetic improvement of grain productivity in wheat., Competing Interests: Conflict of interest The authors have no conflict of interest to declare., (Copyright © 2023 Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Ltd. All rights reserved.)

Ear photosynthesis plays a key role in wheat photosynthesis during the grain filling stage, particularly under drought stress. Thus, dissecting the responsibilities of the glume and awn in photosynthetic carbon fixation and assimilates transportation during the grain filling stage in spikes is imperative. In this study, the detachment of the glume (DG) and awn (DA) of a wheat variety (Pubing143) was used to estimate their influences on ear photosynthesis and dry matter distribution. Radioactive carbon-14 ( 14 C) isotope was detected by a multifunctional liquid scintillation counting system. The accumulation of 14 C assimilates and their contributions to grain weight were then calculated. Under well-watered conditions, ear photosynthesis was reduced by 16.8 % and 46.2 % 25 d after anthesis (DAA) in the de-glumed control (DGC) and de-awned control (DAC) treatments, respectively, compared with the intact ear control (IEC). Under drought stress, ear photosynthesis was reduced by 46 % and 74.2 % at 25 DAA after removing the glume and awn, respectively. Under normal conditions, the number of 14 C assimilates of DGC, and DAC was reduced by 14.6 % and 20.9 % in grains at 25 DAA, respectively, compared with the IEC. Compared with IED, the 14 C assimilates of DGD, and DAD declined by 17.2 % and 27 %, respectively, in grains at 25 DAA under drought conditions. Under well-watered conditions, the grain weight per pot was reduced by 11.2 % and 25.4 % in the de-glumed control (DGC) and de-awned control (DAC) treatments, respectively, compared with the intact ear control (IEC). The grain weight per pot was further reduced after removing the glume and awn (16 % and 32.2 %, respectively) under drought stress. Furthermore, the awn contribution to grain weight was twice that of the glume. Our results suggest that the glume and awn of ears play prominent roles during grain filling in wheat, especially under drought stress, and that the awn is more crucial than the glume., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Authors.)