The vacuolar sulfate transporter PsSULTR4 is a key determinant of seed yield and protein composition in pea.

Pea is a grain legume crop with a high potential to accelerate the food transition due to its high seed protein content and relatively well-balanced amino acid composition. The critical role of external sulfur (S) supply in determining seed yield and seed quality in pea makes it essential to understand the impact of whole plant S management on the trade-off between these two traits. Here, we investigated the physiological relevance of vacuolar sulfate remobilization by targeting PsSULTR4, the only pea sulfate transporter showing substantial similarity to the vacuolar sulfate exporter AtSULTR4;1. Five mutations in PsSULTR4 were identified by TILLING (Targeting Induced Local Lesions IN Genomes), two of which, a loss of function (W78*) and a missense (E568K), significantly decreased seed yield under S deprivation. We demonstrate that PsSULTR4 triggers S distribution from source tissues, especially lower leaves, to reproductive organs to maintain seed yield under S deficiency. Under sufficient S supply, sultr4 seeds display lower levels of the S-rich storage protein PA1 at maturity. They also overaccumulate sulfate in the endosperm at the onset of seed filling. These findings uncover a role of PsSULTR4 in the remobilization of vacuolar sulfate during embryo development, allowing the efficient synthesis of S-rich proteins. Our study uncovers that PsSULTR4 functions (i) in source tissues to remobilize stored vacuolar sulfate for seed production under low S availability and (ii) in developing seeds well supplied with S to fine-tune sulfate remobilization from the endosperm as a critical control point for storage activities in the embryo.

Trehalose-6-phosphate synthase 8 increases photosynthesis and seed yield in Brassica napus.

Trehalose-6-phosphate (T6P) functions as a vital proxy for assessing carbohydrate status in plants. While class II T6P synthases (TPS) do not exhibit TPS activity, they are believed to play pivotal regulatory roles in trehalose metabolism. However, their precise functions in carbon metabolism and crop yield have remained largely unknown. Here, BnaC02.TPS8, a class II TPS gene, is shown to be specifically expressed in mature leaves and the developing pod walls of Brassica napus. Overexpression of BnaC02.TPS8 increased photosynthesis and the accumulation of sugars, starch, and biomass compared to wild type. Metabolomic analysis of BnaC02.TPS8 overexpressing lines and CRISPR/Cas9 mutants indicated that BnaC02.TPS8 enhanced the partitioning of photoassimilate into starch and sucrose, as opposed to glycolytic intermediates and organic acids, which might be associated with TPS activity. Furthermore, the overexpression of BnaC02.TPS8 not only increased seed yield but also enhanced seed oil accumulation and improved the oil fatty acid composition in B. napus under both high nitrogen (N) and low N conditions in the field. These results highlight the role of class II TPS in impacting photosynthesis and seed yield of B. napus, and BnaC02.TPS8 emerges as a promising target for improving B. napus seed yield.

Seed yield as a function of cytokinin-regulated gene expression in wild Kentucky bluegrass (Poa pratensis).

BACKGROUND: Kentucky bluegrass (Poa pratensis L.) panicle development is a coordinated process of cell proliferation and differentiation with distinctive phases and architectural changes that are pivotal to determine seed yield. Cytokinin (CK) is a key factor in determining seed yield that might underpin the second "Green Revolution". However, whether there is a difference between endogenous CK content and seed yields of Kentucky bluegrass, and how CK-related genes are expressed to affect enzyme regulation and downstream seed yield in Kentucky bluegrass remains enigmatic. RESULTS: In order to establish a potential link between CK regulation and seed yield, we dissected and characterized the Kentucky bluegrass young panicle, and determined the changes in nutrients, 6 types of endogenous CKs, and 16 genes involved in biosynthesis, activation, inactivation, re-activation and degradation of CKs during young panicle differentiation of Kentucky bluegrass. We found that high seed yield material had more meristems compared to low seed yield material. Additionally, it was found that seed-setting rate (SSR) and lipase activity at the stage of spikelet and floret primordium differentiation (S3), as well as 1000-grain weight (TGW) and zeatin-riboside (ZR) content at the stages of first bract primordium differentiation (S1) and branch primordium differentiation (S2) showed a significantly positive correlation in the two materials. And zeatin, ZR, dihydrozeatin riboside, isopentenyl adenosine and isopentenyl adenosine riboside contents were higher in seed high yield material than those in seed low yield material at S3 stage. Furthermore, the expressions of PpITP3, PpITP5, PpITP8 and PpLOG1 were positively correlated with seed yield, while the expressions of PpCKX2, PpCKX5 and PpCKX7 were negatively correlated with seed yield in Kentucky bluegrass. CONCLUSIONS: Overall, our study established a relationship between CK and seed yield in Kentucky bluegrass. Perhaps we can increase SSR and TGW by increasing lipase activity and ZR content. Of course, using modern gene editing techniques to manipulate CK related genes such as PpITP3/5/8, PpLOG1 and PpCKX2/5/7, will be a more direct and effective method in Kentucky bluegrass, which requires further trial validation.

BnaC4.BOR2 mediates boron uptake and translocation in Brassica napus under boron deficiency.

Boron (B) is an essential microelement in plant growth and development. However, the molecular mechanisms underlying B uptake and translocation in Brassica napus are poorly understood. Herein, we identified a low-B (LB)-inducible gene, namely BnaC4.BOR2, with high transcriptional activity in root tips, stele cells, leaves, and floral organs. The green fluorescence protein labelled BnaC4.BOR2 protein was localised to the plasma membrane to demonstrate the B efflux activity in yeast and Arabidopsis. BnaC4.BOR2 knockout considerably reduced B concentration in the root and xylem sap, and altered B distribution in different organs at low B supply, exacerbating B sensitivity at the vegetative and reproductive stages. Additionally, the grafting experiment showed that BnaC4.BOR2 expression in the roots contributed more to B deficiency adaptability than that in the shoots. The pot experiments with LB-soil revealed B concentration in leaves and siliques of BnaC4.BOR2 mutants were markedly reduced, showing an obvious B-deficient phenotype of 'flowering without seed setting' and a considerable reduction in seed yield in B-deficient soil. Altogether, the findings of this study highlight the crucial role of BnaC4.BOR2 in B uptake and translocation during B. napus growth and seed yield under LB conditions.

Shattering and yield expression of sesame (Sesamum indicum L) genotypes influenced by paclobutrazol concentration under rainfed conditions of Pothwar.

Seed shattering is a critical challenge that significantly reduces sesame production by 50%. These shattering losses can be reduced by selecting shattering resistant genotypes or by incorporating modern agronomic management such as paclobutrazol, which can boost productivity and prevent seed shattering in sesame. Two-years of field trials were conducted to examine the effect of sesame genotypes, environment, and paclobutrazol (PBZ) concentrations. Twelve sesame genotypes were used in a four-way factorial RCBD with three replications and five PBZ concentrations (T0 = Control; T1 = 150; T2 = 300; T3 = 450; and T4 = 600 mg L- 1) under rainfed conditions of Pothwar. The findings revealed significant variations in the major effects of all examined variables (genotypes, locations, years, and PBZ levels). Sesame genotypes PI-154304 and PI-175907 had the highest plant height, number of capsule plant- 1, seed capsule- 1, 1000 seed weight, biological yield, and seed yield, while also having the lowest seed losses and shattering percentage. Regarding environments, NARC-Islamabad generated the highest plant height, number of capsule plant- 1, shattering percentage, and biological yield; however, the URF-Koont produced the highest seed yield with the lowest shattering percentage. Additionally, plant height, capsules plant- 1, and biological yield were higher in 2021, while seed capsule- 1, 1000 seed weight, seed losses, shattering percentage, and seed yield were higher in 2020. PBZ concentration affected all measured parameters; plant height and number of seed capsule- 1 decreased with increasing PBZ concentrations. 450 mg L- 1 PBZ concentration generated the highest biomass, number of capsules plant- 1, and seed yield. At the same time, PBZ concentration 600 mg L- 1 generated the smallest plant, the lowest seed capsules- 1, the greatest thousand seed weight, and the lowest shattering percentage. The study concluded that paclobutrazol could dramatically reduce shattering percentage and shattering losses while increasing economic returns through better productivity. Based on the findings, the genotypes PI-154304 and PI-175907 with paclobutrazol level 450 mgL- 1 may be suggested for cultivation in Pothwar farming community under rainfed conditions, as they showed promising shattering resistance as well as enhanced growth and yield.

Phospholipid:diacylglycerol acyltransferase1-overexpression stimulates lipid turnover, oil production and fitness in cold-grown plants.

BACKGROUND: Extensive population growth and climate change accelerate the search for alternative ways of plant-based biomass, biofuel and feed production. Here, we focus on hitherto unknow, new promising cold-stimulated function of phospholipid:diacylglycerol acyltransferase1 (PDAT1) - an enzyme catalyzing the last step of triacylglycerol (TAG) biosynthesis. RESULT: Overexpression of AtPDAT1 boosted seed yield by 160% in Arabidopsis plants exposed to long-term cold compared to standard conditions. Such seeds increased both their weight and acyl-lipids content. This work also elucidates PDAT1's role in leaves, which was previously unclear. Aerial parts of AtPDAT1-overexpressing plants were characterized by accelerated growth at early and vegetative stages of development and by biomass weighing three times more than control. Overexpression of PDAT1 increased the expression of SUGAR-DEPENDENT1 (SDP1) TAG lipase and enhanced lipid remodeling, driving lipid turnover and influencing biomass increment. This effect was especially pronounced in cold conditions, where the elevated synergistic expression of PDAT1 and SDP1 resulted in double biomass increase compared to standard conditions. Elevated phospholipid remodeling also enhanced autophagy flux in AtPDAT1-overexpresing lines subjected to cold, despite the overall diminished autophagy intensity in cold conditions. CONCLUSIONS: Our data suggest that PDAT1 promotes greater vitality in cold-exposed plants, stimulates their longevity and boosts oilseed oil production at low temperature.

JcSEUSS1 negatively regulates reproductive organ development in perennial woody Jatropha curcas.

MAIN CONCLUSION: Overexpression of JcSEUSS1 resulted in late flowering, reduced flower number, wrinkled kernels, and decreased seed yield in Jatopha curcas, while downregulation of JcSEUSS1 increased flower number and seed production. The seed oil of Jatropha curcas is suitable as an ideal alternative for diesel fuel, yet the seed yield of Jatropha is restricted by its small number of female flowers and low seed setting rate. Therefore, it is crucial to identify genes that regulate flowering and seed set, and hence improve seed yield. In this study, overexpression of JcSEUSS1 resulted in late flowering, fewer flowers and fruits, and smaller fruits and seeds, causing reduced seed production and oil content. In contrast, the downregulation of JcSEUSS1 by RNA interference (RNAi) technology caused an increase in the flower number and seed yield. However, the flowering time, seed number per fruit, seed weight, and size exhibited no obvious changes in JcSEUSS1-RNAi plants. Moreover, the fatty acid composition also changed in JcSEUSS1 overexpression and RNAi plants, the percentage of unsaturated fatty acids (FAs) was increased in overexpression plants, and the saturated FAs were increased in RNAi plants. These results indicate that JcSEUSS1 played a negative role in regulating reproductive growth and worked redundantly with other genes in the regulation of flowering time, seed number per fruit, seed weight, and size.

The transcription factor BnaA9.WRKY47 coordinates leaf senescence and nitrogen remobilization in Brassica napus.

Nitrogen (N) is an essential macronutrient for plants, and its remobilization is key for adaptation to deficiency stress. However, there is limited understanding of the regulatory mechanisms of N remobilization in the important crop species Brassica napus (oilseed rape). Here, we report the identification of a transcription factor, BnaA9.WRKY47, that is induced by N starvation in a canola variety. At the seedling stage, BnaA9.WRKY47-overexpressing (OE) lines displayed earlier senescence of older leaves and preferential growth of juvenile leaves compared to the wild type under N starvation. At the field scale, the seed yield was significantly increased in the BnaA9.WRKY47-OE lines compared with the wild type when grown under N deficiency conditions and, conversely, it was reduced in BnaA9.WRKY47-knockout mutants. Biochemical analyses demonstrated that BnaA9.WRKY47 directly activates BnaC7.SGR1 to accelerate senescence of older leaves. In line with leaf senescence, the concentration of amino acids in the older leaves of the OE lines was elevated, and the proportion of plant N that they contained was reduced. This was associated with BnaA9.WRKY47 activating the amino acid permease BnaA9.AAP1 and the nitrate transporter BnaA2.NRT1.7. Thus, the expression of BnaA9.WRKY47 efficiently facilitated N remobilization from older to younger leaves or to seeds. Taken together, our results demonstrate that BnaA9.WRKY47 up-regulates the expression of BnaC7.SGR1, BnaA2.NRT1.7, and BnaA9AAP1, thus promoting the remobilization of N in B. napus under starvation conditions.

Transcriptome and Physiological Analysis of Rapeseed Tolerance to Post-Flowering Temperature Increase.

Climate-change-induced temperature fluctuations pose a significant threat to crop production, particularly in the Southern Hemisphere. This study investigates the transcriptome and physiological responses of rapeseed to post-flowering temperature increases, providing valuable insights into the molecular mechanisms underlying rapeseed tolerance to heat stress. Two rapeseed genotypes, Lumen and Solar, were assessed under control and heat stress conditions in field experiments conducted in Valdivia, Chile. Results showed that seed yield and seed number were negatively affected by heat stress, with genotype-specific responses. Lumen exhibited an average of 9.3% seed yield reduction, whereas Solar showed a 28.7% reduction. RNA-seq analysis of siliques and seeds revealed tissue-specific responses to heat stress, with siliques being more sensitive to temperature stress. Hierarchical clustering analysis identified distinct gene clusters reflecting different aspects of heat stress adaptation in siliques, with a role for protein folding in maintaining silique development and seed quality under high-temperature conditions. In seeds, three distinct patterns of heat-responsive gene expression were observed, with genes involved in protein folding and response to heat showing genotype-specific expression. Gene coexpression network analysis revealed major modules for rapeseed yield and quality, as well as the trade-off between seed number and seed weight. Overall, this study contributes to understanding the molecular mechanisms underlying rapeseed tolerance to heat stress and can inform crop improvement strategies targeting yield optimization under changing environmental conditions.

Fertilization depth effect on mechanized direct-seeded winter rapeseed yield and fertilizer use efficiency.

BACKGROUND: Deep fertilization is effective for improving crop yield and fertilizer use efficiency. However, its impact on mechanized direct-seeded rapeseed and the optimal fertilization depth are poorly understood. A field experiment was conducted to evaluate the fertilization depth effect on mechanized direct-seeded rapeseed growth. Five treatments were designed: surface broadcast fertilizer, no fertilization, and fertilizer banded placement at soil depths of 5 (D5), 10 (D10), and 15 cm (D15). RESULTS: Compared with surface broadcast fertilizer, deep fertilization generally increased seed yield and partial factor productivity by 11.0%, agronomic efficiency (AE) by 22.7%, and recovery efficiency (RE) by 79.2% due to the increase of root mass density (16.8%), plant height (8.6%), height of the first branch (10.6%), stem diameter (22.4%), shoot biomass (16.1%), and shoot nitrogen (35.7%), phosphorus (29.7%), and potassium (26.2%) uptake. D10 had the highest seed yield, oil yield, fertilizer use efficiency, and economic benefits at different fertilization depth treatments. Compared with D5 and D15 respectively, D10 increased seed yield by 5.4% and 46.0%, oil yield by 7.7% and 50.5%, partial factor productivity by 5.4% and 46.0%, AE by 9.0% and 99.5%, RE of nitrogen by 48.9% and 34.9%, RE of phosphorus by 83.1% and 38.0%, and RE of potassium by 57.5% and 32.5%. The economic benefits of D10 were CNY 867.31 ha-1 and CNY 4864.23 ha-1 higher than D5 and D15 respectively. CONCLUSION: Considering rapeseed growth and its economic benefits, this study shows that 10 cm is an appropriate placement depth with regard to mechanized direct-seeded winter rapeseed production. © 2022 Society of Chemical Industry.

GmFtsH25 overexpression increases soybean seed yield by enhancing photosynthesis and photosynthates.

Increasing plant photosynthetic capacity is a promising approach to boost yields, but it is particularly challenging in C3 crops, such as soybean (Glycine max (L.) Merr.). Here, we identified GmFtsH25, encoding a member of the filamentation temperature-sensitive protein H protease family, as a major gene involved in soybean photosynthesis, using linkage mapping and a genome-wide association study. Overexpressing GmFtsH25 resulted in more grana thylakoid stacks in chloroplasts and increased photosynthetic efficiency and starch content, while knocking out GmFtsH25 produced the opposite phenotypes. GmFtsH25 interacted with photosystem I light harvesting complex 2 (GmLHCa2), and this interaction may contribute to the observed enhanced photosynthesis. GmFtsH25 overexpression lines had superior yield traits, such as yield per plant, compared to the wild type and knockout lines. Additionally, we identified an elite haplotype of GmFtsH25, generated by natural mutations, which appears to have been selected during soybean domestication. Our study sheds light on the molecular mechanism by which GmFtsH25 modulates photosynthesis and provides a promising strategy for improving the yields of soybean and other crops.

Cold stress and freezing tolerance negatively affect the fitness of Arabidopsis thaliana accessions under field and controlled conditions.

MAIN CONCLUSION: Higher acclimated freezing tolerance improved winter survival, but reduced reproductive fitness of Arabidopsis thaliana accessions under field and controlled conditions. Low temperature is one of the most important abiotic factors influencing plant fitness and geographical distribution. In addition, cold stress is known to influence crop yield and is therefore of great economic importance. Increased freezing tolerance can be acquired by the process of cold acclimation, but this may be associated with a fitness cost. To assess the influence of cold stress on the fitness of plants, long-term field trials over 5 years were performed with six natural accessions of Arabidopsis thaliana ranging from very tolerant to very sensitive to freezing. Fitness parameters, as seed yield and 1000 seed mass, were measured and correlation analyses with temperature and freezing tolerance data performed. The results were compared with fitness parameters from controlled chamber experiments over 3 years with application of cold priming and triggering conditions. Winter survival and seed yield per plant were positively correlated with temperature in field experiments. In addition, winter survival and 1000 seed mass were correlated with the cold-acclimated freezing tolerance of the selected Arabidopsis accessions. The results provide strong evidence for a trade-off between higher freezing tolerance and reproductive fitness in A. thaliana, which might have ecological impacts in the context of global warming.

Increasing floral visitation and hybrid seed production mediated by beauty mark in Gossypium hirsutum.

Hybrid crop varieties have been repeatedly demonstrated to produce significantly higher yields than their parental lines; however, the low efficiency and high cost of hybrid seed production has limited the broad exploitation of heterosis for cotton production. One option for increasing the yield of hybrid seed is to improve pollination efficiency by insect pollinators. Here, we report the molecular cloning and characterization of a semidominant gene, Beauty Mark (BM), which controls purple spot formation at the base of flower petals in the cultivated tetraploid cotton species Gossypium barbadense. BM encodes an R2R3 MYB113 transcription factor, and we demonstrate that GbBM directly targets the promoter of four flavonoid biosynthesis genes to positively regulate petal spot development. Introgression of a GbBM allele into G. hirsutum by marker-assisted selection restored petal spot formation, which significantly increased the frequency of honeybee visits in G. hirsutum. Moreover, field tests confirmed that cotton seed yield was significantly improved in a three-line hybrid production system that incorporated the GbBM allele. Our study thus provides a basis for the potentially broad application of this gene in improving the long-standing problem of low seed production in elite cotton hybrid lines.

Downregulation of a gibberellin 3ß-hydroxylase enhances photosynthesis and increases seed yield in soybean.

Seed yield, determined mainly by seed numbers and seed weight, is the primary target of soybean breeding. Identifying the genes underlying yield-related traits is of great significance. Through joint linkage mapping and a genome-wide association study for 100-seed weight, we cloned GmGA3ox1, a gene encoding gibberellin 3ß-hydroxylase, which is the key enzyme in the gibberellin synthesis pathway. Genome resequencing identified a beneficial GmGA3ox1 haplotype contributing to high seed weight, which was further confirmed by soybean transformants. CRISPR/Cas9-generated gmga3ox1 mutants showed lower seed weight, but promoted seed yield by increasing seed numbers. The gmga3ox1 mutants reduced gibberellin biosynthesis while enhancing photosynthesis. Knockout of GmGA3ox1 resulted in the upregulation of numerous photosynthesis-related genes, particularly the GmRCA family encoding ribulose-1,5-bispho-sphate carboxylase-oxygenase (Rubisco) activases. The basic leucine zipper transcription factors GmbZIP97 and GmbZIP159, which were both upregulated in the gmga3ox1 mutants and induced by the gibberellin synthesis inhibitor uniconazole, could bind to the promoter of GmRCAß and activate its expression. Analysis of genomic sequences with over 2700 soybean accessions suggested that GmGA3ox1 is being gradually utilized in modern breeding. Our results elucidated the important role of GmGA3ox1 in soybean yield. These findings reveal important clues for future high-yield breeding in soybean and other crops.

MYC transcription factors coordinate tryptophan-dependent defence responses and compromise seed yield in Arabidopsis.

Robust plant immunity negatively affects other fitness traits, including growth and seed production. Jasmonate (JA) confers broad-spectrum protection against plant consumers by stimulating the degradation of JASMONATE ZIM-DOMAIN (JAZ) proteins, which in turn relieves repression on transcription factors (TFs) coincident with reduced growth and fecundity. The molecular mechanisms underlying JA-mediated decreases in fitness remain largely unknown. To assess the contribution of MYC TFs to growth and reproductive fitness at high levels of defence, we mutated three MYC genes in a JAZ-deficient mutant (jazD) of Arabidopsis thaliana that exhibits strong defence and low seed yield. Genetic epistasis analysis showed that de-repression of MYC TFs in jazD not only conferred strong resistance to insect herbivory but also reduced shoot and root growth, fruit size and seed yield. We also provided evidence that the JAZ-MYC module coordinates the supply of tryptophan with the production of indole glucosinolates and the proliferation of endoplasmic reticulum bodies that metabolise glucosinolates through the action of ß-glucosidases. Our results establish MYCs as major regulators of growth- and reproductive-defence trade-offs and further indicate that these factors coordinate tryptophan availability with the production of amino acid-derived defence compounds.

The SINGLE FLOWER (SFL) gene encodes a MYB transcription factor that regulates the number of flowers produced by the inflorescence of chickpea.

Legumes usually have compound inflorescences, where flowers/pods develop from secondary inflorescences (I2), formed laterally at the primary inflorescence (I1). Number of flowers per I2, characteristic of each legume species, has important ecological and evolutionary relevance as it determines diversity in inflorescence architecture; moreover, it is also agronomically important for its potential impact on yield. Nevertheless, the genetic network controlling the number of flowers per I2 is virtually unknown. Chickpea (Cicer arietinum) typically produces one flower per I2 but single flower (sfl) mutants produce two (double-pod phenotype). We isolated the SFL gene by mapping the sfl-d mutation and identifying and characterising a second mutant allele. We analysed the effect of sfl on chickpea inflorescence ontogeny with scanning electron microscopy and studied the expression of SFL and meristem identity genes by RNA in situ hybridisation. We show that SFL corresponds to CaRAX1/2a, which codes a MYB transcription factor specifically expressed in the I2 meristem. Our findings reveal SFL as a central factor controlling chickpea inflorescence architecture, acting in the I2 meristem to regulate the length of the period for which it remains active, and therefore determining the number of floral meristems that it can produce.

Priming of Arabidopsis resistance to herbivory by insect egg deposition depends on the plant's developmental stage.

While traits of plant resistance to herbivory often change during ontogeny, it is unknown whether the primability of this resistance depends on the plant's developmental stage. Resistance in non-flowering Arabidopsis thaliana against Pieris brassicae larvae is known to be primable by prior egg deposition on leaves. We investigated whether this priming effect is maintained in plants at the flowering stage. Larval performance assays revealed that flowering plants' resistance to herbivory was not primable by egg deposition. Accordingly, transcriptomes of flowering plants showed almost no response to eggs. In contrast, egg deposition on non-flowering plants enhanced the expression of genes induced by subsequent larval feeding. Strikingly, flowering plants showed constitutively high expression levels of these genes. Larvae performed generally worse on flowering than on non-flowering plants, indicating that flowering plants constitutively resist herbivory. Furthermore, we determined the seed weight in regrown plants that had been exposed to eggs and larvae during the non-flowering or flowering stage. Non-flowering plants benefitted from egg priming with a smaller loss in seed yield. The seed yield of flowering plants was unaffected by the treatments, indicating tolerance towards the larvae. Our results show that the primability of anti-herbivore defences in Arabidopsis depends on the plant's developmental stage.

Genetic dissection of seed yield and yield-related traits in Brassica napus grown with contrasting nitrogen supplies.

Oilseed rape (B. napus) is the main oil crop in China as well as in the world. Nitrogen (N) deficiency significantly reduces the seed yield of B. napus. However, a very few studies involved in the genetic mechanism of seed yield and SY-related traits of B. napus in response to N deficiency. In this study, plant height (PH), branch number per plant (BN), pod number per plant (PN), seed number per pod (SN), 1000-seed weight (SW), and seed yield per plant (SY) were investigated using a B. napus double haploid (BnaTNDH) population derived from a cross between cultivars "Tapidor" and "Ningyou7" grown at an optimal N (ON) and a low N (LN) supplies in three-year field trials. Great variations of SY and related traits were observed in BnaTNDH population under contrasting N supplies. A total of 106 and 110 significant quantitative trait loci (QTLs) were detected for six traits at ON and LN in three field trials, respectively. All of these significant QTLs for the same trait identified in two or three trials were integrated into 20 stable QTLs. A total of 50 consensus QTLs and 53 unique QTLs were obtained from 172 significant QTLs and 20 stable QTLs, including 35 ON-specific QTLs, 29 LN-specific QTLs and 39 constitutive QTLs detected at both ON and LN. cqA3l was integrated from four QTLs for PN, PH, SN, SY at LN, cqC9c was integrated from QTLs for BN, SY, PN at ON and LN. Both cqA3l and cqC9c were detected in three trials. In addition, a total of 194 epistatic interactions, inculding 15 pleiotropic epistatic interactions, were identified. Eight of the 15 pleiotropic epistatic interactions were detected to affect SY. This result may help to better understand the genetic mechanism of yield traits in response to low N and promote the breeding of N-efficient varieties. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-022-01281-0.

Genome-wide association study identifies candidate genes and favorable haplotypes for seed yield in Brassica napus.

Oilseed rape (Brassica napus L.) is one of the most essential oil crops. Genetic improvement of seed yield (SY) is a major aim of B. napus breeding. Several studies have been reported on the genetic mechanisms of SY of B. napus. Here, a genome-wide association study (GWAS) of SY was conducted using a panel of 403 natural accessions of B. napus, with more than five million high-quality single-nucleotide polymorphisms (SNPs). A total of 1773 significant SNPs were detected associated with SY, and 783 significant SNPs were co-located with previously reported QTLs. The lead SNPs chrA01__8920351 and chrA02__4555979 were jointly detected in Trial 2_2 and Trial 2_mean value, and in Trial 1_2 and Trial 1_mean value, respectively. Subsequently, two candidate genes of BnaA01g17200D and BnaA02g08680D were identified through combining transcriptome, candidate gene association analysis, and haplotype analysis. BnaA09g10430D detected through lead SNP chrA09__5160639 was associated with SY of B. napus. Our results provide valuable information for studying the genetic control of seed yield in B. napus and valuable genes, haplotypes, and cultivars resources for the breeding of high seed yield B. napus cultivars. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-022-01332-6.

BnERF114.A1, a Rapeseed Gene Encoding APETALA2/ETHYLENE RESPONSE FACTOR, Regulates Plant Architecture through Auxin Accumulation in the Apex in Arabidopsis.

Plant architecture is crucial for rapeseed breeding. Here, we demonstrate the involvement of BnERF114.A1, a transcription factor for ETHYLENE RESPONSE FACTOR (ERF), in the regulation of plant architecture in Brassica napus. BnERF114.A1 is a member of the ERF family group X-a, encoding a putative 252-amino acid (aa) protein, which harbours the AP2/ERF domain and the conserved CMX-1 motif. BnERF114.A1 is localised to the nucleus and presents transcriptional activity, with the functional region located at 142-252 aa of the C-terminus. GUS staining revealed high BnERF114.A1 expression in leaf primordia, shoot apical meristem, leaf marginal meristem, and reproductive organs. Ectopic BnERF114.A1 expression in Arabidopsis reduced plant height, increased branch and silique number per plant, and improved seed yield per plant. Furthermore, in Arabidopsis, BnERF114.A1 overexpression inhibited indole-3-acetic acid (IAA) efflux, thus promoting auxin accumulation in the apex and arresting apical dominance. Therefore, BnERF114.A1 probably plays an important role in auxin-dependent plant architecture regulation.