Search Results (33)

Applying a top dressing of nitrogen fertilizer before harvesting spring tea is vital for producing high-quality spring tea. However, the interaction between the sprouting phenological characteristics of various cultivars and the timing of top dressing remains unclear. A field trial was conducted to investigate such interaction. Urea enriched with ¹⁵N was applied to soil of the early-sprouting cultivar Jia-ming-1 (JM1) and the late-sprouting cultivar Tie-guan-yin (TGY) on 29 January (early application, EApp) or 10 March (late application, LApp), respectively. The bud density and yield of young spring shoots were significantly decreased in LApp compared to EApp. Such differences were more remarkable in the early-sprouting cultivar (JM1) than in the late-sprouting cultivar (TGY). The N_dff (N derived from ¹⁵N-enriched urea) in mature leaves and young spring shoots as well as the amount of ¹⁵N in young spring shoots were all higher in EApp than in LApp. N_dff in both mature leaves (R² = 0.99, p < 0.001) and young spring shoots (R² = 0.61–0.89, p < 0.01) could be well predicted by the growing degree days of the duration between the N fertilization and sampling. N_dff and ¹⁵N concentrations in mature leaves were significantly correlated with the content of nitrate and the ratio of ammonium to total inorganic nitrogen. Partial least squares path modeling revealed that thermal condition directly affected soil N supply and soil pH and thereby affected N_dff in mature leaves and young spring shoots. Our findings highlight the importance of early pre-spring topdressing of N fertilizer to improve the yield and N use efficiency of spring tea in both early- and late-sprouting tea cultivars. The work identified a synergistic effect of N uptake by tea plants, N transformation, and soil pH related to the thermo-conditions of early and late N topdressing. Full article

Pre-harvest sprouting (PHS) of wheat poses a major challenge to global food security due to its negative impact on grain yield and quality. In the present study, we conducted the validation of previously published markers or functional markers associated with PHS resistance in a panel of 200 wheat cultivars adapted to Southeastern European conditions. In field experiments conducted in four environments in Croatia, the germination index (GI) was assessed, and significant genetic, environmental, and genotype–environment interactions were detected. The broad-sense heritability for GI was high (0.86), confirming the predominant role of genetic factors in determining PHS resistance. Twenty-two polymorphic SNP markers were analyzed for their effects on GI, of which nine markers from chromosomes 3A, 3B, 4A, 5A, and 7B showed significant genotypic effects across environments, especially TaMKK3-A and wsnp_Ex_rep_c66324_64493429. In addition, nine marker combinations were identified, which showed significant differences in GI between allele combinations. Overall, this study elucidates the genetic basis of PHS resistance in wheat cultivars adapted to the agro-climatic conditions of Southeast Europe and provides insights for marker-assisted breeding strategies to improve PHS resistance. Full article

The TaVP1-B gene, located on the 3B chromosome of wheat, is a homolog of the Viviparous-1 (VP-1) gene of maize and was reported to confer resistance to pre-harvest sprouting (PHS) in wheat. In this study, the structure of the TaVP1-B gene was analyzed using the wheat pan-genome consisting of 20 released cultivars (19 wheat are from China), and 3 single nucleotide polymorphisms (SNPs), which were identified at the 496 bp, 524 bp, and 1548 bp of the TaVP1-B CDS region, respectively. Haplotypes analysis showed that these SNPs were in complete linkage disequilibrium and that only two haplotypes designated as hap1 (TGG) and hap2 (GAA) were present. Association analysis between TaVP1-B haplotypes and PHS resistance of the 20 wheat cultivars in four experiment environments revealed that the average PHS resistance of accessions with hap1 was significantly better than that of accessions with hap2, which infers the effects of TaVP1-B on wheat PHS resistance. To further investigate the impacts of alleles at the TaVP1-B locus on PHS resistance, the SNP at 1548 bp of the TaVP1-B CDS region was converted to a KASP marker, which was used for genotyping 304 Chinese wheat cultivars, whose PHS resistance was evaluated in three environments. The average sprouting rates (SRs) of 135 wheat cultivars with the hap1 were significantly lower than the 169 cultivars with the hap2, validating the impacts of TaVP1-B on PHS resistance in Chinese wheat. The present study provided the breeding-friendly marker for functional variants in the TaVP1-B gene, which can be used for genetic improvement of PHS resistance in wheat. Full article

We generated and characterized knockout mutant lines of the OsPHS3 gene using the CRISPR/Cas9 system. The knockout lines of the OsPHS3 gene showed that 1 bp and 7 bp deletion, early termination codons were used for protein production. Agronomic characteristics of knock-out lines were reduced in plant height, culm diameter, panicle length, seed size and weight, except for the number of tillers. In addition, we analyzed the expression levels of carotenoid biosynthesis genes by qRT-PCR. Among the genes encoding carotenoid metabolic pathway enzymes, the level of transcripts of PSY1, PSY2, PSY3, PDS and ZDS were higher in the KO lines than in the WT line. In contrast, transcription of the ε-LCY, β-LCY and ZEP1 genes were downregulated in the KO lines compared to the WT line. Also, the KO lines decreased carotenoid content and ABA amount compared to WT, while preharvest sprouts increased. These results suggested that they would certainly help explain the molecular mechanisms of PHS in other crops, such as wheat and barley, which are susceptible to PHS. Full article

The Huanghuai winter wheat region, China’s primary wheat-producing area, predominantly cultivates white-grained wheat. Pre-harvest sprouting (PHS) significantly impacts yield and quality, making the breeding of PHS-resistant varieties crucial for ensuring China’s wheat production security. This study evaluated the PHS rate of 344 white-grained wheat varieties over two consecutive growing seasons (2022/2023 and 2023/2024). Furthermore, it analyzed the effects of allelic variations and their combinations in six genes (Tamyb10, TaDFR, TaMKK3-A, TaGASR34, Tasdr, and TaMFT) on PHS resistance. Results revealed average PHS rates of 66.1% and 64.4% for the two growing seasons, with coefficients of variation of 39.1% and 40.2%, respectively, and a narrow-sense heritability of 0.72. These findings indicate substantial genetic variation and relatively high genetic stability within the tested materials. Among the six molecular markers examined, the superior haplotype GS34-7Bb exhibited the lowest average PHS rate (41.9%) over two growing seasons, demonstrating the strongest PHS resistance. Analysis of different haplotype combinations identified two advantageous genotypes for PHS resistance in white-grained wheat: TaMKK3-Ab + GS34-7Bb + Tasdr-2Aa + TaMFT-A1b (average PHS rate: 20.8%) and TaMKK3-Ab + GS34-7Bb + Tasdr-2Ab + TaMFT-A1b (average PHS rate: 34.2%). Notably, the distribution frequency of superior haplotypes of PHS-related genes and these two advantageous haplotype combinations showed varying degrees of decline over time. Full article

In this study, BC1F3:4 generation plants derived from the hybrid crosses of Rio Blanco × Nevzatbey, Rio Blanco × Adana99, and Rio Blanco × line 127 were used as experimental material. These hybrids incorporated QTLs associated with pre-harvest sprouting (PHS) resistance through molecular techniques. Key agronomic traits, including plant height, spike length, the number of grains per spike, grain weight, and physiological maturity, were evaluated in both greenhouse and growth room settings under accelerated growth (speed breeding) conditions. Results indicated that plants grown in the fully controlled greenhouse conditions exhibited superior agronomic performance compared with those cultivated in the growth room. Additionally, germination tests were conducted on each hybrid cross to identify genotypes exhibiting dormancy. The analysis revealed that 11 lines from the Rio Blanco × Nevzatbey combination, eight lines from Rio Blanco × Adana99, and six lines from Rio Blanco × Line 127 had notably low germination indices. Among the three hybrid families, the Rio Blanco × Nevzatbey BC1F3:4 hybrids demonstrated the lowest germination index (0.44). Furthermore, Rio Blanco itself recorded the lowest germination index under both greenhouse (0.02) and growth room (0.24) conditions. These findings suggest that environmental conditions exert a significant influence on the expression of dormancy in these genotypes, even when dormancy genes are present. The lines developed in this research have the potential to serve as elite material in breeding programs aimed at enhancing pre-harvest sprouting resistance. Full article

Pre-harvest sprouting (PHS) is a complex abiotic stress caused by multiple exogenous and endogenous variables that results in random but significant quality and yield loss at the terminal crop stage in more than half of the wheat-producing areas of the world. Systematic research over more than five decades suggests that addressing this challenge requires tools beyond the traditional genetic manipulation approach. Previous molecular studies indicate a possible role of epigenetics in the regulation of seed dormancy and PHS in crops, especially through RNA-directed DNA methylation (RdDM) pathways mediated by Argonaute (AGO) proteins. In this study, we explore the role of the AGO802B gene associated with PHS resistance in wheat, through the presence of a SINE retrotransposon insertion. The current study found the SINE insertion at 3′UTR of the TaAGO802B present in 73.2% of 41 cultivars analyzed and in 92.6% of the resistant cultivar subset. The average expression of TaAGO802B in cultivars with the SINE insertion was 73.3% lower than in cultivars without insertion. This study also indicated a significant positive correlation between the PHS score and methylation levels in the cultivars. The resistant cultivars with the SINE insertion recorded 54.7% lower methylation levels than susceptible cultivars. Further analysis of a DH population (Sadash × P2711) reveals that SINE insertion co-segregates with PHS resistance. This sets forth the SINE insertion in TaAGO802B as a genetic marker for screening wheat germplasm and as an efficient tool for breeding PHS-resistant wheat cultivars. Full article

During the domestication of crops, seed dormancy has been reduced or eliminated to encourage faster and more consistent germination. This alteration makes cultivated crops particularly vulnerable to pre-harvest sprouting, which occurs when mature crops are subjected to adverse environmental conditions, such as excessive rainfall or high humidity. Consequently, some seeds may bypass the normal dormancy period and begin to germinate while still attached to the mother plant before harvest. Grains affected by pre-harvest sprouting are characterized by increased levels of α-amylase activity, resulting in poor processing quality and immediate grain downgrading. In the agriculture industry, pre-harvest sprouting causes annual economic losses exceeding USD 1 billion worldwide. This premature germination is influenced by a complex interplay of genetic, biochemical, and molecular factors closely linked to environmental conditions like rainfall. However, the exact mechanism behind this process is still unclear. Unlike pre-harvest sprouting, vivipary refers to the germination process and the activation of α-amylase during the soft dough stage, when the grains are still immature. Mature seeds with reduced levels of ABA or impaired ABA signaling (weak dormancy) are more susceptible to pre-harvest sprouting. While high seed dormancy can enhance resistance to pre-harvest sprouting, it can lead to undesirable outcomes for most crops, such as non-uniform seedling establishment after sowing. Thus, resistance to pre-harvest sprouting is crucial to ensuring productivity and sustainability and is an agronomically important trait affecting yield and grain quality. On the other hand, seed color is linked to sprouting resistance; however, the genetic relationship between both characteristics remains unresolved. The identification of mitogen-activated protein kinase kinase-3 (MKK3) as the gene responsible for pre-harvest sprouting-1 (Phs-1) represents a significant advancement in our understanding of how sprouting in wheat is controlled at the molecular and genetic levels. In seed maturation, Viviparous-1 (Vp-1) plays a crucial role in managing pre-harvest sprouting by regulating seed maturation and inhibiting germination through the suppression of α-amylase and proteases. Vp-1 is a key player in ABA signaling and is essential for the activation of the seed maturation program. Mutants of Vp-1 exhibit an unpigmented aleurone cell layer and exhibit precocious germination due to decreased sensitivity to ABA. Recent research has also revealed that TaSRO-1 interacts with TaVp-1, contributing to the regulation of seed dormancy and resistance to pre-harvest sprouting in wheat. The goal of this review is to emphasize the latest research on pre-harvest sprouting in crops and to suggest possible directions for future studies. Full article

Pre-harvest sprouting (PHS) resistance is a complex trait, and many genes influencing the germination process of winter wheat have already been described. In the light of interannual climate variation, breeding for PHS resistance will remain mandatory for wheat breeders. Several tests and traits are used to assess PHS resistance, i.e., sprouting scores, germination index, and falling number (FN), but the variation of these traits is highly dependent on the weather conditions during field trials. Here, we present a method to assess falling number stability (FNS) employing an after-ripening period and the wetting of the kernels to improve trait variation and thus trait heritability. Different genome-based prediction scenarios within and across two subsequent seasons based on overall 400 breeding lines were applied to assess the predictive abilities of the different traits. Based on FNS, the genome-based prediction of the breeding values of wheat breeding material showed higher correlations across seasons ($r=0.505-0.548$) compared to those obtained for other traits for PHS assessment ($r=0.216-0.501$). By weighting PHS-associated quantitative trait loci (QTL) in the prediction model, the average predictive abilities for FNS increased from 0.585 to 0.648 within the season 2014/2015 and from 0.649 to 0.714 within the season 2015/2016. We found that markers in the Phs-A1 region on chromosome 4A had the highest effect on the predictive abilities for FNS, confirming the influence of this QTL in wheat breeding material, whereas the dwarfing genes Rht-B1 and Rht-D1 and the wheat–rye translocated chromosome T1RS.1BL exhibited effects, which are well-known, on FN per se exclusively. Full article

The association between pre-harvest sprouting (PHS) and seed coat color has long been recognized. Red-grained wheats generally exhibit greater PHS resistance compared to white-grained wheat, although variability in PHS resistance exists within red-grained varieties. Here, we conducted a genome-wide association study on a panel consisting of red-grained wheat varieties, aimed at uncovering genes that modulate PHS resistance and red color components of seed coat using digital image processing. Twelve loci associated with PHS traits were identified, nine of which were described for the first time. Genetic loci marked by SNPs AX-95172164 (chromosome 1B) and AX-158544327 (chromosome 7D) explained approximately 25% of germination index variance, highlighting their value for breeding PHS-resistant varieties. The most promising candidate gene for PHS resistance was TraesCS6B02G147900, encoding a protein involved in aleurone layer morphogenesis. Twenty-six SNPs were significantly associated with grain color, independently of the known Tamyb10 gene. Most of them were related to multiple color characteristics. Prioritization of genes within the revealed loci identified TraesCS1D03G0758600 and TraesCS7B03G1296800, involved in the regulation of pigment biosynthesis and in controlling pigment accumulation. In conclusion, our study identifies new loci associated with grain color and germination index, providing insights into the genetic mechanisms underlying these traits. Full article

The introduction of quinoa into new growing regions and environments is of interest to farmers, consumers, and stakeholders around the world. Many plant breeding programs have already started to adapt quinoa to the environmental and agronomic conditions of their local fields. Formal quinoa breeding efforts in Washington State started in 2010, led by Professor Kevin Murphy out of Washington State University. Preharvest sprouting appeared as the primary obstacle to increased production in the coastal regions of the Pacific Northwest. Preharvest sprouting (PHS) is the undesirable sprouting of seeds that occurs before harvest, is triggered by rain or humid conditions, and is responsible for yield losses and lower nutrition in cereal grains. PHS has been extensively studied in wheat, barley, and rice, but there are limited reports for quinoa, partly because it has only recently emerged as a problem. This study aimed to better understand PHS in quinoa by adapting a PHS screening method commonly used in cereals. This involved carrying out panicle-wetting tests and developing a scoring scale specific for panicles to quantify sprouting. Assessment of the trait was performed in a diversity panel (N = 336), and the resulting phenotypes were used to create PHS tolerance rankings and undertake a GWAS analysis (n = 279). Our findings indicate that PHS occurred at varying degrees across a subset of the quinoa germplasm tested and that it is possible to access PHS tolerance from natural sources. Ultimately, these genotypes can be used as parental lines in future breeding programs aiming to incorporate tolerance to PHS. Full article

The excavation and utilization of dormancy loci in breeding are effective endeavors for enhancing the resistance to pre-harvest sprouting (PHS) of wheat varieties. CH1539 is a wheat breeding line with high-level seed dormancy. To clarify the dormant loci carried by CH1539 and obtain linked molecular markers, in this study, a recombinant inbred line (RIL) population derived from the cross of weak dormant SY95-71 and strong dormant CH1539 was genotyped using the Wheat17K single-nucleotide polymorphism (SNP) array, and a high-density genetic map covering 21 chromosomes and consisting of 2437 SNP markers was constructed. Then, the germination percentage (GP) and germination index (GI) of the seeds from each RIL were estimated. Two QTLs for GP on chromosomes 5A and 6B, and four QTLs for GI on chromosomes 5A, 6B, 6D and 7A were identified. Among them, the QTL on chromosomes 6B controlling both GP and GI, temporarily named QGp/Gi.sxau-6B, is a major QTL for seed dormancy with the maximum phenotypic variance explained of 17.66~34.11%. One PCR-based diagnostic marker Ger6B-3 for QGp/Gi.sxau-6B was developed, and the genetic effect of QGp/Gi.sxau-6B on the RIL population and a set of wheat germplasm comprising 97 accessions was successfully confirmed. QGp/Gi.sxau-6B located in the 28.7~30.9 Mbp physical position is different from all the known dormancy loci on chromosomes 6B, and within the interval, there are 30 high-confidence annotated genes. Our results revealed a novel QTL QGp/Gi.sxau-6B whose CH1539 allele had a strong and broad effect on seed dormancy, which will be useful in further PHS-resistant wheat breeding. Full article

Pre-harvest sprouting (PHS) is a condition triggered by environmental factors, particularly prevalent in humid conditions, leading to substantial yield losses in black gram. While the potential for genotypic PHS tolerance exists, it has not been thoroughly assessed in black gram. Hence, the present study aimed to delve into the genetic variation for PHS tolerance in diverse black gram (Vigna mungo (L.) Hepper) germplasm, and also to comprehend the impact of various physical and physiological traits on PHS. A diverse set of 112 black gram accessions collected across the phytogeographical zones of India were examined for their seed and pod characteristics. Water absorption by pods and seeds and fresh-seed germination was calculated by following the standard procedure given by the International Seed Testing Association. The alpha-amylase activity was measured on dry seeds (0 h), 24 h, 48 h, and 72 h after germination of each accession, using a UV-VIS spectrophotometer, and hard-seededness was measured using a texture analyzer machine. The results showed a wide range in PHS tolerance and FSG, and 13 accessions were found to be PHS-tolerant (PHS value < 10%). An indicator of PHS, seed germination in a pod, ranged from 2.75% in IC485641 (highly tolerant to PHS) to 95.85% in IC530501 (highly susceptible to PHS). Correlation and multivariate analysis revealed that PHS was positively correlated with water imbibition by pod and seed, fresh-seed germination and alpha-amylase activity. PHS-tolerant accessions showed a slow increase in alpha-amylase activity, in contrast to PHS-susceptible accessions. The utilization of alpha-amylase activity as a biochemical marker has the potential for evaluating PHS tolerance across various black gram accessions. The identified PHS-tolerant accessions can be used as donors in crop improvement programs aimed at developing PHS-tolerant black gram varieties. Full article

Pre-harvest sprouting (PHS), the germination of seeds on the plant prior to harvest, poses significant challenges to agriculture. It not only reduces seed and grain yield, but also impairs the commodity quality of the fruit, ultimately affecting the success of the subsequent crop cycle. A deeper understanding of PHS is essential for guiding future breeding strategies, mitigating its impact on seed production rates and the commercial quality of fruits. PHS is a complex phenomenon influenced by genetic, physiological, and environmental factors. Many of these factors exert their influence on PHS through the intricate regulation of plant hormones responsible for seed germination. While numerous genes related to PHS have been identified in food crops, the study of PHS in vegetable crops is still in its early stages. This review delves into the regulatory elements, functional genes, and recent research developments related to PHS in vegetable crops. Meanwhile, this paper presents a novel understanding of PHS, aiming to serve as a reference for the study of this trait in vegetable crops. Full article

Accurate, rapid testing platforms are essential for early detection and mitigation of late maturity α-amylase (LMA) and preharvest sprouting (PHS) in wheat. These conditions are characterized by elevated α-amylase levels and negatively impact flour quality, resulting in substantial economic losses. The Hagberg–Perten Falling Number (FN) method is the industry standard for measuring α-amylase activity in wheatmeal. However, FN does not directly detect α-amylase and has major limitations. Developing α-amylase immunoassays would potentially enable early, accurate detection regardless of testing environment. With this goal, we assessed an expression of α-amylase isoforms during seed development. Transcripts of three of the four isoforms were detected in developing and mature grain. These were cloned and used to develop E. coli expression lines expressing single isoforms. After assessing amino acid conservation between isoforms, we identified peptide sequences specific to a single isoform (TaAMY1) or that were conserved in all isoforms, to develop monoclonal antibodies with targeted specificities. Three monoclonal antibodies were developed, anti-TaAMY1-A, anti-TaAMY1-B, and anti-TaAMY1-C. All three detected endogenous α-amylase(s). Anti-TaAMY1-A was specific for TaAMY1, whereas anti-TaAMY1-C detected TaAMY1, 2, and 4. Thus, confirming that they possessed the intended specificities. All three antibodies were shown to be compatible for use with immuno-pulldown and immuno-assay applications. Full article