RESUMO
Plants generally enhance their root growth in the form of greater biomass and/or root length to boost nutrient uptake in response to short-term low nitrogen (LN). However, the underlying mechanisms of short-term LN-mediated root growth remain largely elusive. Our genome-wide association study, haplotype analysis, and phenotyping of transgenic plants showed that the crucial nitrate signaling component NIN-LIKE PROTEIN3.2 (ZmNLP3.2), a positive regulator of root biomass, is associated with natural variations in root biomass of maize (Zea mays L.) seedlings under LN. The monocot-specific gene AUXIN/INDOLE-3-ACETIC ACID14 (ZmAux/IAA14) exhibited opposite expression patterns to ZmNLP3.2 in ZmNLP3.2 knockout and overexpression lines, suggesting that ZmNLP3.2 hampers ZmAux/IAA14 transcription. Importantly, ZmAux/IAA14 knockout seedlings showed a greater root dry weight (RDW), whereas ZmAux/IAA14 overexpression reduced RDW under LN compared with wild-type plants, indicating that ZmAux/IAA14 negatively regulates the RDW of LN-grown seedlings. Moreover, in vitro and vivo assays indicated that AUXIN RESPONSE FACTOR19 (ZmARF19) binds to and transcriptionally activates ZmAux/IAA14, which was weakened by the ZmNLP3.2-ZmARF19 interaction. The zmnlp3.2 ZmAux/IAA14-OE seedlings exhibited further reduced RDW compared to ZmAux/IAA14 overexpression lines when subjected to LN treatment, corroborating the ZmNLP3.2-ZmAux/IAA14 interaction. Thus, our study reveals a ZmNLP3.2-ZmARF19-ZmAux/IAA14 module regulating root biomass in response to nitrogen limitation in maize.
RESUMO
Complete disruption of critical genes is generally accompanied by severe growth and developmental defects, which dramatically hinder its utilization in crop breeding. Identifying subtle changes, such as single nucleotide polymorphisms (SNPs), in critical genes that specifically modulate a favorable trait is a prerequisite to fulfill breeding potential. Here, we found two SNPs in the E-class floral organ identity gene cucumber (Cucumis sativus) SEPALLATA2 (CsSEP2) that specifically regulate fruit length. Haplotype (HAP) 1 (8G2667A) and HAP2 (8G2667T) exist in natural populations, whereas HAP3 (8A2667T) is induced by ethyl methanesulfonate mutagenesis. Phenotypic characterization of four near-isogenic lines and a mutant line showed that HAP2 fruits are significantly longer than those of HAP1, and those of HAP3 are 37.8% longer than HAP2 fruit. The increasing fruit length in HAP1-3 was caused by a decreasing inhibitory effect on CRABS CLAW (CsCRC) transcription (a reported positive regulator of fruit length), resultinged in enhanced cell expansion. Moreover, a 7638G/A-SNP in melon (Cucumis melo) CmSEP2 modulates fruit length in a natural melon population via the conserved SEP2-CRC module. Our findings provide a strategy for utilizing essential regulators with pleiotropic effects during crop breeding.
RESUMO
As a maternal tissue, the pericarp supports and protects for other components of seed, such as embryo and endosperm. Despite the importance of maize pericarp in seed, the genome-wide transcriptome pattern throughout maize pericarp development has not been well characterized. Here, we developed RNA-seq transcriptome atlas of B73 maize pericarp development based on 21 samples from 5 days before fertilization (DBP5) to 32 days after fertilization (DAP32). A total of 25 346 genes were detected in programming pericarp development, including 1887 transcription factors (TFs). Together with pericarp morphological changes, the global clustering of gene expression revealed four developmental stages: undeveloped, thickening, expansion and strengthening. Coexpression analysis provided further insights on key regulators in functional transition of four developmental stages. Combined with non-seed, embryo, endosperm, and nucellus transcriptome data, we identified 598 pericarp-specific genes, including 75 TFs, which could elucidate key mechanisms and regulatory networks of pericarp development. Cell wall related genes were identified that reflected their crucial role in the maize pericarp structure building. In addition, key maternal proteases or TFs related with programmed cell death (PCD) were proposed, suggesting PCD in the maize pericarp was mediated by vacuolar processing enzymes (VPE), and jasmonic acid (JA) and ethylene-related pathways. The dynamic transcriptome atlas provides a valuable resource for unraveling the genetic control of maize pericarp development.
Assuntos
Transcriptoma , Zea mays , Transcriptoma/genética , Zea mays/metabolismo , Endosperma/metabolismo , Sementes/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Regulação da Expressão Gênica de Plantas/genéticaRESUMO
Development of the endosperm is strikingly different in monocots and dicots: it often manifests as a persistent tissue in the former and transient tissue in the latter. Little is known about the controlling mechanisms responsible for these different outcomes. Here we characterized a maize (Zea mays) mutant, endosperm breakdown1 (enb1), in which the typically persistent endosperm (PE) was drastically degraded during kernel development. ENB1 encodes a cellulose synthase 5 that is predominantly expressed in the basal endosperm transfer layer (BETL) of endosperm cells. Loss of ENB1 function caused a drastic reduction in formation of flange cell wall ingrowths (ingrowths) in BETL cells. Defective ingrowths impair nutrient uptake, leading to premature utilization of endosperm starch to nourish the embryo. Similarly, developing wild-type kernels cultured in vitro with a low level of sucrose manifested early endosperm breakdown. ENB1 expression is induced by sucrose via the BETL-specific Myb-Related Protein1 transcription factor. Overexpression of ENB1 enhanced development of flange ingrowths, facilitating sucrose transport into BETL cells and increasing kernel weight. The results demonstrated that ENB1 enhances sucrose supply to the endosperm and contributes to a PE in the kernel.
Assuntos
Endosperma , Zea mays , Parede Celular/metabolismo , Endosperma/metabolismo , Glucosiltransferases , Sacarose/metabolismo , Zea mays/metabolismoRESUMO
Maize (Zea mays) originated in tropical areas and is thus susceptible to low temperatures, which pose a major threat to maize production. Our understanding of the molecular basis of cold tolerance in maize is limited. Here, we identified bZIP68, a basic leucine zipper (bZIP) transcription factor, as a negative regulator of cold tolerance in maize. Transcriptome analysis revealed that bZIP68 represses the cold-induced expression of DREB1 transcription factor genes. The stability and transcriptional activity of bZIP68 are controlled by its phosphorylation at the conserved Ser250 residue under cold stress. Furthermore, we demonstrated that the bZIP68 locus was a target of selection during early domestication. A 358-bp insertion/deletion (Indel-972) polymorphism in the bZIP68 promoter has a significant effect on the differential expression of bZIP68 between maize and its wild ancestor teosinte. This study thus uncovers an evolutionary cis-regulatory variant that could be used to improve cold tolerance in maize.
Assuntos
Fatores de Transcrição , Zea mays , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Domesticação , Regiões Promotoras Genéticas/genética , Fatores de Transcrição/metabolismo , Zea mays/metabolismoRESUMO
Maternal-to-filial nutrition transfer is central to grain development and yield. nitrate transporter 1/peptide transporter (NRT1-PTR)-type transporters typically transport nitrate, peptides, and ions. Here, we report the identification of a maize (Zea mays) NRT1-PTR-type transporter that transports sucrose and glucose. The activity of this sugar transporter, named Sucrose and Glucose Carrier 1 (SUGCAR1), was systematically verified by tracer-labeled sugar uptake and serial electrophysiological studies including two-electrode voltage-clamp, non-invasive microelectrode ion flux estimation assays in Xenopus laevis oocytes and patch clamping in HEK293T cells. ZmSUGCAR1 is specifically expressed in the basal endosperm transfer layer and loss-of-function mutation of ZmSUGCAR1 caused significantly decreased sucrose and glucose contents and subsequent shrinkage of maize kernels. Notably, the ZmSUGCAR1 orthologs SbSUGCAR1 (from Sorghum bicolor) and TaSUGCAR1 (from Triticum aestivum) displayed similar sugar transport activities in oocytes, supporting the functional conservation of SUGCAR1 in closely related cereal species. Thus, the discovery of ZmSUGCAR1 uncovers a type of sugar transporter essential for grain development and opens potential avenues for genetic improvement of seed-filling and yield in maize and other grain crops.
Assuntos
Grão Comestível , Glucose , Transportadores de Nitrato , Transportador 1 de Peptídeos , Proteínas de Plantas , Sacarose , Zea mays , Humanos , Grão Comestível/genética , Grão Comestível/crescimento & desenvolvimento , Glucose/metabolismo , Células HEK293 , Transportadores de Nitrato/genética , Transportadores de Nitrato/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sacarose/metabolismo , Zea mays/crescimento & desenvolvimento , Zea mays/metabolismo , Transportador 1 de Peptídeos/genética , Transportador 1 de Peptídeos/metabolismo , Transporte BiológicoRESUMO
Seed number and harvesting ability in maize (Zea mays L.) are primarily determined by the architecture of female inflorescence, namely the ear. Therefore, ear morphogenesis contributes to grain yield and as such is one of the key target traits during maize breeding. However, the molecular networks of this highly dynamic and complex grain-bearing inflorescence remain largely unclear. As a first step toward characterizing these networks, we performed a high-spatio-temporal-resolution investigation of transcriptomes using 130 ear samples collected from developing ears with length from 0.1 mm to 19.0 cm. Comparisons of these mRNA populations indicated that these spatio-temporal transcriptomes were clearly separated into four distinct stages stages I, II, III, and IV. A total of 23 793 genes including 1513 transcription factors (TFs) were identified in the investigated developing ears. During the stage I of ear morphogenesis, 425 genes were predicted to be involved in a co-expression network established by eight hub TFs. Moreover, 9714 ear-specific genes were identified in the seven kinds of meristems. Additionally, 527 genes including 59 TFs were identified as especially expressed in ear and displayed high temporal specificity. These results provide a high-resolution atlas of gene activity during ear development and help to unravel the regulatory modules associated with the differentiation of the ear in maize.
Assuntos
Transcriptoma , Zea mays , Transcriptoma/genética , Zea mays/genética , Melhoramento Vegetal , Fenótipo , Sementes/genética , Grão Comestível/genética , Regulação da Expressão Gênica de Plantas/genéticaRESUMO
Competitive coevolution between microbes and viruses has led to the diversification of CRISPR-Cas defense systems against infectious agents. By analyzing metagenomic terabase datasets, we identified two compact families (775 to 803 amino acids (aa)) of CRISPR-Cas ribonucleases from hypersaline samples, named Cas13X and Cas13Y. We engineered Cas13X.1 (775 aa) for RNA interference experiments in mammalian cell lines. We found Cas13X.1 could tolerate single-nucleotide mismatches in RNA recognition, facilitating prophylactic RNA virus inhibition. Moreover, a minimal RNA base editor, composed of engineered deaminase (385 aa) and truncated Cas13X.1 (445 aa), exhibited robust editing efficiency and high specificity to induce RNA base conversions. Our results suggest that there exist untapped bacterial defense systems in natural microbes that can function efficiently in mammalian cells, and thus potentially are useful for RNA-editing-based research.
Assuntos
Sistemas CRISPR-Cas , Edição de RNA , RNA Bacteriano , Animais , Proteínas de Bactérias , Linhagem Celular , Clonagem Molecular , Bases de Dados de Ácidos Nucleicos , Cães , Humanos , Camundongos , Interferência de RNARESUMO
The Elongator complex was originally identified as an interactor of hyperphosphorylated RNA polymerase II (RNAPII) in yeast and has histone acetyltransferase (HAT) activity. However, the genome-wide regulatory roles of Elongator on transcriptional elongation and histone acetylation remain unclear. We characterized a maize miniature seed mutant, mn7 and map-based cloning revealed that Mn7 encodes one of the subunits of the Elongator complex, ZmELP1. ZmELP1 deficiency causes marked reductions in the kernel size and weight. Molecular analyses showed that ZmELP1 interacts with ZmELP3, which is required for H3K14 acetylation (H3K14ac), and Elongator complex subunits interact with RNA polymerase II (RNAPII) C-terminal domain (CTD). Genome-wide analyses indicated that loss of ZmELP1 leads to a significant decrease in the deposition of H3K14ac and the CTD of phosphorylated RNAPII on Ser2 (Ser2P). These chromatin changes positively correlate with global transcriptomic changes. ZmELP1 mutation alters the expression of genes involved in transcriptional regulation and kernel development. We also showed that the decrease of Ser2P depends on the deposition of Elongator complex-mediated H3K14ac. Taken together, our results reveal an important role of ZmELP1 in the H3K14ac-dependent transcriptional elongation, which is critical for kernel development.
Assuntos
Histonas , RNA Polimerase II , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Histonas/metabolismo , Zea mays/genética , Zea mays/metabolismo , Fosforilação , Acetilação , Estudo de Associação Genômica Ampla , Saccharomyces cerevisiae/genéticaRESUMO
Maize is one of the most important crops for food, cattle feed and energy production. However, maize is frequently attacked by various pathogens and pests, which pose a significant threat to maize yield and quality. Identification of quantitative trait loci and genes for resistance to pests will provide the basis for resistance breeding in maize. Here, a ß-glucosidase ZmBGLU17 was identified as a resistance gene against Pythium aphanidermatum, one of the causal agents of corn stalk rot, by genome-wide association analysis. Genetic analysis showed that both structural variations at the promoter and a single nucleotide polymorphism at the fifth intron distinguish the two ZmBGLU17 alleles. The causative polymorphism near the GT-AG splice site activates cryptic alternative splicing and intron retention of ZmBGLU17 mRNA, leading to the downregulation of functional ZmBGLU17 transcripts. ZmBGLU17 localizes in both the extracellular matrix and vacuole and contribute to the accumulation of two defence metabolites lignin and DIMBOA. Silencing of ZmBGLU17 reduces maize resistance against P. aphanidermatum, while overexpression significantly enhances resistance of maize against both the oomycete pathogen P. aphanidermatum and the Asian corn borer Ostrinia furnacalis. Notably, ZmBGLU17 overexpression lines exhibited normal growth and yield phenotype in the field. Taken together, our findings reveal that the apoplastic and vacuolar localized ZmBGLU17 confers resistance to both pathogens and insect pests in maize without a yield penalty, by fine-tuning the accumulation of lignin and DIMBOA.
Assuntos
Zea mays , beta-Glucosidase , Animais , Bovinos , Zea mays/genética , Zea mays/química , beta-Glucosidase/genética , Estudo de Associação Genômica Ampla , Lignina , Melhoramento Vegetal , InsetosRESUMO
Carbon and nitrogen are the two main nutrients in maize (Zea mays L.) kernels, and kernel filling and metabolism determine seed formation and germination. However, the molecular mechanisms underlying the relationship between kernel filling and corresponding carbon and nitrogen metabolism remain largely unknown. Here, we found that HEAT SHOCK PROTEIN 90.6 (HSP90.6) is involved in both seed filling and the metabolism processes of carbon and nitrogen. A single-amino acid mutation within the HATPase_c domain of HSP90.6 led to small kernels. Transcriptome profiling showed that the expression of amino acid biosynthesis- and carbon metabolism-related genes was significantly downregulated in the hsp90.6 mutant. Further molecular evidence showed strong interactions between HSP90.6 and the 26S proteasome subunits REGULATORY PARTICLE NON-ATPASE6 (RPN6) and PROTEASOME BETA SUBUNITD2 (PBD2). The mutation of hsp90.6 significantly reduced the activity of the 26S proteasome, resulting in the accumulation of ubiquitinated proteins and defects in nitrogen recycling. Moreover, we verified that HSP90.6 is involved in carbon metabolism through interacting with the 14-3-3 protein GENERAL REGULATORY FACTOR14-4 (GF14-4). Collectively, our findings revealed that HSP90.6 is involved in seed filling and development by interacting with the components controlling carbon and nitrogen metabolism.
Assuntos
Carbono , Sementes , Carbono/metabolismo , Sementes/metabolismo , Aminoácidos/metabolismo , Nitrogênio/metabolismo , Proteínas de Choque Térmico/metabolismo , Zea mays/metabolismoRESUMO
A CRISPR/Cas12i.3-based gene editing platform is established in broomcorn millet (Panicum miliaceum) and used to create new elite germplasm for this ancient crop.
Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Mutagênese , Panicum , Sistemas CRISPR-Cas/genética , Panicum/genética , Mutagênese/genética , Edição de Genes/métodosRESUMO
KEY MESSAGE: Here we provided a high temporal-resolution transcriptome atlas of maize embryo sac and ovule to reveal the gene activity dynamic during early seed development. The early maize (Zea mays) seed development is initiated from double fertilization in the embryo sac and needs to undergo a highly dynamic and complex development process to form the differentiated embryo and endosperm. Despite the importance of maize seed for food, feed, and biofuel, many regulators responsible for controlling its early development are not known yet. Here, we reported a high temporal-resolution transcriptome atlas of embryo sac and ovule based on 44 time point samples collected within the first four days of seed development. A total of 25,187 genes including 1598 transcription factors (TFs) involved in early seed development were detected. Global comparisons of the expressions of these genes revealed five distinct development stages of early seed, which are mainly related to double fertilization, asymmetric cell division of the zygote, as well as coenocyte formation, cellularization and differentiation in endosperm. We identified 3327 seed-specific genes, which more than one thousand seed-specific genes with main expressions during early seed development were newly identified here, including 859 and 186 genes predominantly expressed in the embryo sac and ovule, respectively. Combined with the published transcriptome data of seed, we uncovered the dominant auxin biosynthesis, transport and signaling related genes at different development stages and subregions of seed. These results are helpful for understanding the genetic control of early seed development.
Assuntos
Transcriptoma , Zea mays , Zea mays/genética , Óvulo Vegetal , Sementes/genética , Endosperma/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
The sodium cation (Na+ ) is the predominant cation with deleterious effects on crops in salt-affected agricultural areas. Salt tolerance of crop can be improved by increasing shoot Na+ exclusion. Therefore, it is crucial to identify and use genetic variants of various crops that promote shoot Na+ exclusion. Here, we show that a HKT1 family gene ZmNC3 (Zea mays L. Na+ Content 3; designated ZmHKT1;2) confers natural variability in shoot-Na+ accumulation and salt tolerance in maize. ZmHKT1;2 encodes a Na+ -preferential transporter localized in the plasma membrane, which mediates shoot Na+ exclusion, likely by withdrawing Na+ from the root xylem flow. A naturally occurring nonsynonymous SNP (SNP947-G) increases the Na+ transport activity of ZmHKT1;2, promoting shoot Na+ exclusion and salt tolerance in maize. SNP947-G first occurred in the wild grass teosinte (at a allele frequency of 43%) and has become a minor allele in the maize population (allele frequency 6.1%), suggesting that SNP947-G is derived from teosinte and that the genomic region flanking SNP947 likely has undergone selection during domestication or post-domestication dispersal of maize. Moreover, we demonstrate that introgression of the SNP947-G ZmHKT1;2 allele into elite maize germplasms reduces shoot Na+ content by up to 80% and promotes salt tolerance. Taken together, ZmNC3/ZmHKT1;2 was identified as an important QTL promoting shoot Na+ exclusion, and its favourable allele provides an effective tool for developing salt-tolerant maize varieties.
Assuntos
Tolerância ao Sal , Zea mays , Tolerância ao Sal/genética , Zea mays/genética , Zea mays/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sódio/metabolismo , Alelos , Proteínas de Membrana Transportadoras/metabolismoRESUMO
The CRISPR-Cas systems have been widely used as genome editing tools, with type II and V systems typically introducing small indels, and type I system mediating long-range deletions. However, the precision of type I systems for large fragment deletion is still remained to be optimized. Here, we developed a compact Cascade-Cas3 Dvu I-C system with Cas11c for plant genome editing. The Dvu I-C system was efficient to introduce controllable large fragment deletion up to at least 20 kb using paired crRNAs. The paired-crRNAs design also improved the controllability of deletions for the type I-E system. Dvu I-C system was sensitive to spacer length and mismatch, which was benefit for target specificity. In addition, we showed that the Dvu I-C system was efficient for generating stable transgenic lines in maize and rice with the editing efficiency up to 86.67%. Overall, Dvu I-C system we developed here is powerful for achieving controllable large fragment deletions.
Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Sistemas CRISPR-Cas/genética , Plantas/genética , Genoma de Planta , Mutação INDELRESUMO
Stalk lodging, which is generally determined by stalk strength, results in considerable yield loss and has become a primary threat to maize (Zea mays) yield under high-density planting. However, the molecular genetic basis of maize stalk strength remains unclear, and improvement methods remain inefficient. Here, we combined map-based cloning and association mapping and identified the gene stiff1 underlying a major quantitative trait locus for stalk strength in maize. A 27.2-kb transposable element insertion was present in the promoter of the stiff1 gene, which encodes an F-box domain protein. This transposable element insertion repressed the transcription of stiff1, leading to the increased cellulose and lignin contents in the cell wall and consequently greater stalk strength. Furthermore, a precisely edited allele of stiff1 generated through the CRISPR/Cas9 system resulted in plants with a stronger stalk than the unedited control. Nucleotide diversity analysis revealed that the promoter of stiff1 was under strong selection in the maize stiff-stalk group. Our cloning of stiff1 reveals a case in which a transposable element played an important role in maize improvement. The identification of stiff1 and our edited stiff1 allele pave the way for efficient improvement of maize stalk strength.
Assuntos
Elementos de DNA Transponíveis/genética , Regiões Promotoras Genéticas , Zea mays/genética , Alelos , Sistemas CRISPR-Cas , Parede Celular/metabolismo , Mapeamento Cromossômico , Genes de Plantas , Lignina/metabolismo , Fenótipo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Locos de Características Quantitativas , Análise de Sequência , Transformação GenéticaRESUMO
KEY MESSAGE: A point mutation of RPM1 triggers persistent immune response that induces leaf premature senescence in wheat, providing novel information of immune responses and leaf senescence. Leaf premature senescence in wheat (Triticum aestivum L.) is one of the most common factors affecting the plant's development and yield. In this study, we identified a novel wheat mutant, yellow leaf and premature senescence (ylp), which exhibits yellow leaves and premature senescence at the heading and flowering stages. Consistent with the yellow leaves phenotype, ylp had damaged and collapsed chloroplasts. Map-based cloning revealed that the phenotype of ylp was caused by a point mutation from Arg to His at amino acid 790 in a plasma membrane-localized protein resistance to Pseudomonas syringae pv. maculicola 1 (RPM1). The point mutation triggered excessive immune responses and the upregulation of senescence- and autophagy-associated genes. This work provided the information for understanding the molecular regulatory mechanism of leaf senescence, and the results would be important to analyze which mutations of RPM1 could enable plants to obtain immune activation without negative effects on plant growth.
Assuntos
Pseudomonas syringae , Triticum , Triticum/genética , Triticum/metabolismo , Pseudomonas syringae/metabolismo , Proteínas de Plantas/metabolismo , Aminoácidos/metabolismo , Folhas de Planta , Mutação , Regulação da Expressão Gênica de PlantasRESUMO
A novel exclusive ß-selective O-aryl glycosylation was developed using glycosyl chloride and arylboronic acid with a palladium catalyst under an air atmosphere. The reaction was insensitive to moisture and characterized using readily available and bench-stable glycosyl chloride and arylboronic acid as substrates. A diverse range of substrate scopes, including various arylboronic acids and glycosyl chloride donors, was well-tolerated in this method. Arylboronic acid was oxidized by O2 in air to produce phenol as the aromatic source. This new strategy provides an alternative route and may find broad applications in efficient synthesis of bioactive O-aryl glycosides in the future.
RESUMO
BACKGROUND: Maize kernel row number (KRN) is one of the most important yield traits and has changed greatly during maize domestication and selection. Elucidating the genetic basis of KRN will be helpful to improve grain yield in maize. RESULTS: Here, we measured KRN in four environments using a nested association mapping (NAM) population named HNAU-NAM1 with 1,617 recombinant inbred lines (RILs) that were derived from 12 maize inbred lines with a common parent, GEMS41. Then, five consensus quantitative trait loci (QTLs) distributing on four chromosomes were identified in at least three environments along with the best linear unbiased prediction (BLUP) values by the joint linkage mapping (JLM) method. These QTLs were further validated by the separate linkage mapping (SLM) and genome-wide association study (GWAS) methods. Three KRN genes cloned through the QTL assay were found in three of the five consensus QTLs, including qKRN1.1, qKRN2.1 and qKRN4.1. Two new QTLs of KRN, qKRN4.2 and qKRN9.1, were also identified. On the basis of public RNA-seq and genome annotation data, five genes highly expressed in ear tissue were considered candidate genes contributing to KRN. CONCLUSIONS: This study carried out a comprehensive analysis of the genetic architecture of KRN by using a new NAM population under multiple environments. The present results provide solid information for understanding the genetic components underlying KRN and candidate genes in qKRN4.2 and qKRN9.1. Single-nucleotide polymorphisms (SNPs) closely linked to qKRN4.2 and qKRN9.1 could be used to improve inbred yield during molecular breeding in maize.
Assuntos
Locos de Características Quantitativas , Zea mays , Mapeamento Cromossômico/métodos , Grão Comestível/genética , Estudo de Associação Genômica Ampla , Fenótipo , Zea mays/genéticaRESUMO
Endoplasmic reticulum (ER) type I signal peptidases (ER SPases I) are vital proteases that cleave signal peptides from secreted proteins. However, the specific function of ER SPase I in plants has not been genetically characterized, and the substrate is largely unknown. Here, we report the identification of a maize (Zea mays) miniature seed6 (mn6) mutant. The loss-of-function mn6 mutant exhibited severely reduced endosperm size. Map-based cloning and molecular characterization indicated that Mn6 is an S26-family ER SPase I, with Gly102 (box E) in Mn6 critical for protein function during processing. Mass spectrometric and immunoprecipitation analyses revealed that Mn6 is predominantly involved in processing carbohydrate synthesis-related proteins, including the cell wall invertase miniature seed1 (Mn1), which is specifically expressed in the basal endosperm transfer layer. RNA and protein expression levels of Mn1 were both significantly downregulated in the mn6 mutant. Due to the significant reduction in cell wall invertase activity in the transfer cell layer, mutation of Mn6 caused dramatic defects in endosperm development. These results suggest that proper maturation of Mn1 by Mn6 may be a crucial step for proper seed filling and maize development.