Crop Journal最新文献

In animals, serotonin is a neurotransmitter and mood regulator. In plants, serotonin functions in energy acquisition, tissue maintenance, delay of senescence, and response to biotic and abiotic stresses. In this study, we examined the effect of serotonin enrichment of rice endosperm on plant growth, endosperm development, and grain quality. To do so, TDCs and T5H were selected as targets for serotonin fortification. Overexpression of TDC1 or TDC3 increased serotonin accumulation relative to overexpression of T5H in rice grain. Transgenic lines of target genes driven by the Gt1 promoter showed better field performance than those driven by the Ubi promoter. Overexpression of T5H showed little effect on plant growth or grain physicochemical quality. In neuronal cell culture assays, serotonin induced neuroprotective action against apoptosis. Breeding of rice cultivars with high serotonin content may be beneficial for health and nutrition.

Ferredoxins (Fds) in plastids are the most upstream stromal electron receptors shuttling electrons to downstream metabolic systems and function in various physiological processes of dicots, but their roles in monocots’ response to stresses are still unclear. In this study, the functions of OsFd4, the major non-photosynthetic type Fd in rice, were characterized under oxidative stress and Xanthomonas oryzae pv. oryzae (Xoo) infection. OsFd4-knockout mutants displayed no defects in key agronomic traits and blast resistance, but were more sensitive to hydrogen peroxide (H₂O₂) treatment than the wild type. Transient expression of OsFd4 alleviated H₂O₂-induced rice cell death, suggesting that OsFd4 contributes to rice tolerance to exogenous oxidative stress. Deletion of OsFd4 enhanced rice immune responses against Xoo. OsFd4 formed a complex in vivo with itself and OsFd1, the major photosynthetic Fd in rice, and OsFd1 transcripts were increased in leaf and root tissues of the OsFd4-knockout mutants. These results indicate that OsFd4 is involved in regulating rice defense against stresses and interplays with OsFd1.

Relay cropping of Poaceae and Fabaceae promotes high yield and land-use efficiency by allowing a double harvest. However, it is difficult to increase yield synergistically because of the reduced photosynthetic abilities of legume leaves under the shade of graminoids. Leaf photosynthetic capacity in relay cropping systems is associated with ecological niche differentiation and photosynthetic compensation after restoration of normal light. We conducted a field experiment in southwest China in 2020–2021 to evaluate the effects of three cropping patterns: maize–soybean relay cropping (IMS), monoculture maize (MM), and monoculture soybean (SS), and N application levels: no N application (NN:0 kg N ha⁻¹), reduced N (RN: 180 kg N ha⁻¹), and conventional N (CN: 240 kg N ha⁻¹). Compared to monocropping, relay cropping increased the stay-green traits of maize and soybean by 13% and 89%, respectively. Relay cropping prolonged the leaf stay-green duration in the maize and soybean lag phase by almost 4 and 8 days, respectively. Relay cropping maize (IM) increased the leaf area index (LAI) by 79.4% to 88.5% under NN and 55.5% to 148% under RN. Relay cropping soybean (IS) increased the LAI from 115% to 437% at days 40 to 50 after anthesis. IM increased yield by 65.6%. IS increased yield by 9.7%. HI and system yield were at their highest values under RN. In the relay cropping system, reduced N application extended green leaf duration, increased photosynthesis inside the canopy at multiple levels, ultimately increases soybean yield synergistically.

Mitochondrial protein translation that is essential for aerobic energy production includes four essential steps of the mitochondrial ribosome cycle, namely, initiation, elongation, termination of the polypeptide, and ribosome recycling. Translation termination initiates when a stop codon enters the A site of the mitochondrial ribosome where it is recognized by a dedicated peptide release factor (RF). However, RFs and mechanisms involved in translation in plant mitochondria, especially in monocotyledons, remain largely unknown. Here, we identified a crumpled kernel (crk5 allele) mutant, with significantly decreased kernel size, 100-kernel weight, and an embryo-lethal phenotype. The Crk5 allele was isolated using map-based cloning and found to encode a mitochondrial localization RF2a. As it is an ortholog of Arabidopsis mitochondrial RF2a, we named the gene ZmmtRF2a. ZmmtRF2a is missing the 5th–7th exons in the crk5 resulting in deletion of domains containing motifs GGQ and SPF that are essential for release activity of RF, mitochondrial ribosome binding, and stop codon recognition. Western blot and qRT-PCR analyses indicate that the crk5 mutation results in abnormal mitochondrion structure and function. Intriguingly, we observed a feedback loop in the crk5 with up-regulated transcript levels detected for several mitochondrial ribosome and mitochondrial-related components, in particular mitochondrial complexes CI, CIV, and a ribosome assembly related PPR. Together, our data support a crucial role for ZmmtRF2a in regulation of mitochondrial structure and function in maize.

Despite the longstanding importance of silage as a critical feed source for ruminants, its quality improvement has been largely overlooked. Although numerous quantitative trait loci (QTL) and genes affecting silage quality in maize have been reported, only a few have been effectively incorporated into breeding programs. Addressing this gap, the present study undertook a comprehensive meta-QTL (MQTL) analysis involving 523 QTL associated with silage-quality traits collected from 14 published studies. Of the 523 QTL, 405 were projected onto a consensus map comprising 62,424 genetic markers, resulting in the identification of 60 MQTL and eight singletons. The average confidence interval (CI) of the MQTL was 3.9-fold smaller than that of the source QTL. Nine of the 60 identified MQTL were classified as breeder’s MQTL owing to their small CIs, involvement of more QTL, and large contribution to phenotypic variation. One-third of the MQTL co-localized with DNA marker-trait associations identified in previous genome-wide association mapping studies. A set of 78 high-confidence candidate genes influencing silage quality were identified in the MQTL regions. These genes and associated markers may advance marker-assisted breeding for maize silage quality.

Soybean (Glycine max) is a major oil and feed crop worldwide. Soybean mosaic virus (SMV) is a globally occurring disease that severely reduces the yield and quality of soybean. Here, we characterized the role of the clock gene TIMING OF CAB EXPRESSION 1b (GmTOC1b) in the resistance of soybean to SMV. Homozygous Gmtoc1b mutants exhibited increased tolerance to SMV strain SC3 due to the activation of programmed cell death triggered by a hypersensitive response. Transcriptome deep sequencing and RT-qPCR analysis suggested that GmTOC1b likely regulates the expression of target genes involved in the salicylic acid (SA) signaling pathway. GmTOC1b binds to the promoter of GmWRKY40, which encodes a protein that activates the expression of SA-mediated defense-related genes. Moreover, we revealed that the GmTOC1b^H1 haplotype, which confers increased tolerance to SMV, was artificially selected in improved cultivars from the Northern and Huang-Huai regions of China. Our results therefore identify a previously unknown SMV resistance component that could be deployed in the molecular breeding of soybean to enhance SMV resistance.

Plant trichomes are a specialized cellular tissue that functions in resistance to biotic and abiotic stresses. In rice, three transcription-factor genes: OsWOX3B, HL6, and OsSPL10, have been found to control trichome development. Although studies have shown interactions between the three genes, their full relationship in trichome development is unclear. We found that the expression levels of OsWOX3B and HL6 were both reduced in OsSPL10-knockout plants but increased in OsSPL10-overexpression plants, suggesting that OsSPL10 positively regulates their expression. Physical interaction between OsSPL10 and OsWOX3B was found both in vivo and in vitro and attenuated their abilities to bind to the promoter of HL6 to activate its transcription. This mechanism may regulate trichome length by adjusting the expression of HL6. A rice gene network regulating trichome development is proposed.

The plant natural product scopolin, a coumarin secondary metabolite, has been extensively exploited in flavor, cosmetic, medicine, and other industrial fields. Melilotus albus, a leguminous rotation crop, contains high concentrations of coumarin. The transcriptional regulatory network that controls the flow through the scopolin biosynthesis pipeline in M. albus remains poorly understood. MabHLH11 encodes a basic helix–loop–helix (bHLH) transcription factor whose transcription is positively associated with scopolin accumulation and with the expression of MaMYB4, the bHLH partner of the MYB-bHLH complex. Phylogenetic analysis grouped MabHLH11 in the TRANSPARENT TESTA 8 (TT8) clade of the bHLH IIIf subgroup. The MabHLH11 protein contained an MYB-interacting region and physically interacted with MaMYB4 in yeast and tobacco leaves. Co-overexpression of MabHLH11 with MaMYB4 in M. albus additively increased the expression of UDP-glucosyltransferase (MaUGT79) and induced more scopolin accumulation than occurred under the expression of MabHLH11 alone. MabHLH11 directly targeted the promoter of MaUGT79 and the activation of MabHLH11 was strengthened by the presence of MaMYB4. Thus, MaMYB4 enhanced the function of MabHLH11 in upregulating scopolin biosynthesis in M. albus, providing a theoretical basis for scalable production of a high-value plant natural product.

Water and nitrogen fertilization are the key factors limiting maize productivity. The genetic basis of interactions between maize genotype, water, and nitrogen is unclear. A recombinant inbred line (RIL) maize population was evaluated for seven yield and five agronomic traits under four water and nitrogen conditions: water stress and low nitrogen, water stress and high nitrogen, well-watered and low nitrogen, and well-watered and high nitrogen. Respectively eight, six, and six traits varied in response to genotype–water interactions, genotype–nitrogen interactions, and genotype–water–nitrogen interactions. Using a linkage map consisting of 896 single-nucleotide polymorphism markers and multiple-environmental quantitative-trait locus (QTL) mapping, we identified 31 QTL, including 12 for genotype–water–nitrogen interaction, across the four treatments. A set of 8060 genes were differentially expressed among treatments. Integrating genetic analysis, gene co-expression, and functional annotation revealed two candidate genes controlling genotype–water–nitrogen interactions, affecting both leaf width and grain yield. Genes involved in abscisic acid biosynthesis and bZIP, NAC, and WRKY transcription factors participated in maize response to water and nitrogen conditions. These results represent a step toward understanding the genetic regulatory network of maize that responds to water and nitrogen stress and provide a theoretical basis for the genetic improvement of both water- and nitrogen-use efficiency.

Salt and drought stress are common abiotic factors that exert a detrimental influence on seed germination, potentially leading to significantly impaired growth and production in rice. Gaining a comprehensive understanding of the molecular response of seeds to abiotic stress during the germination is of paramount importance. In the present study, we identified two R3-MYB genes in rice, namely OsTCL1 and OsTCL2, and characterized their roles in regulating seed germination under salt and drought stress. Plants with tcl1 and tcl2 mutant alleles exhibited delayed seed germination, particularly under stress conditions. The tcl1 tcl2 double mutant showed an even more pronounced reduction in germination during initial stages of germination, thereby indicating a redundant regulatory function of OsTCL1 and OsTCL2 in seed germination under abiotic stresses. Furthermore, we demonstrated that the transcript levels of several phospholipase D (PLD) genes were downregulated in the tcl1 tcl2 mutant, resulting in a decreased level of the phosphatidic acid (PA) product. Application of 1-butanol, a competitive substrate inhibitor of PLD-dependent production of PA, attenuated the stress response of the tcl1 tcl2 mutant. This suggests that OsTCL1 and OsTCL2 partially modulate seed germination through the PLD-PA signaling pathway. Moreover, there were alterations in the expression of genes involved in abscisic acid (ABA) biosynthesis, metabolism and signaling transduction in the double mutant. These changes affected the endogenous ABA level and ABA response, thereby influencing seed germination. Application of both 1-butanol and ABA synthesis inhibitor sodium tungstate (Na₂WO₄) nearly eliminated the differences in stress response between wild type and the tcl1 tcl2 mutant. This indicates that OsTCL1 and OsTCL2 synergistically coordinate seed germination under abiotic stresses through both the PLD-PA signaling and ABA-mediated pathways.