Crop Journal最新文献

Plants adaptively change their cell wall composition and structure during their growth, development, and interactions with environmental stresses. Dirigent proteins (DIRs) contribute to environmental adaptations by dynamically reorganizing the cell wall and/or by generating defense compounds. A maize DIR, ZmDRR206, was previously reported to play a dominant role in regulation of storage nutrient accumulation in endosperm during maize kernel development. Here we show that ZmDRR206 mediates maize seedling growth and disease resistance by coordinately regulating biosynthesis of cell wall components for cell-wall integrity (CWI) maintenance. Expression of ZmDRR206 was induced in maize seedlings upon pathogen infection. ZmDRR206 overexpression in maize resulted in reduced seedling growth and photosynthetic activity but increased disease resistance and drought tolerance, revealing a tradeoff between growth and defense. Consistently, ZmDRR206 overexpression reduced the contents of primary metabolites and down-regulated genes involved in photosynthesis, while increasing the contents of major cell wall components, defense phytohormones, and defense metabolites, and up-regulated genes involved in defense and cell-wall biosynthesis in seedlings. ZmDRR206-overexpressing seedlings were resistant to cell-wall stress imposed by isoxaben, and ZmDRR206 physically interacted with ZmCesA10, which is a cellulose synthase unit. Our findings suggest a mechanism by which ZmDRR206 coordinately regulates biosynthesis of cell-wall components for CWI maintenance during maize seedling growth, and might be exploited for breeding strong disease resistance in maize.

Superior inbred lines are central to maize breeding as sources of natural variation. Although many elite lines have been sequenced, less sequencing attention has been paid to newly developed lines. We constructed a genome assembly of the elite inbred line KA105, which has recently been developed by an artificial breeding population named Shaan A and has shown desirable characteristics for breeding. Its pedigree showed genetic divergence from B73 and other lines in its pedigree. Comparison with the B73 reference genome revealed extensive structural variation, 58 presence/absence variation (PAV) genes, and 1023 expanded gene families, some of which may be associated with disease resistance. A network-based integrative analysis of stress-induced transcriptomes identified 13 KA105-specific PAV genes, of which eight were induced by at least one kind of stress, participating in gene modules responding to stress such as drought and southern leaf blight disease. More than 200,000 gene pairs were differentially correlated between KA105 and B73 during kernel development. The KA105 reference genome and transcriptome atlas are a resource for further germplasm improvement and surveys of maize genomic variation and gene function.

Flower development and plant architecture determine the efficiency of mechanized harvest and seed yield in Brassica napus. Although TERMINAL FLOWER 1 (AtTFL1) is a regulator of flower development in Arabidopsis thaliana, the function and regulatory mechanism of TFL1 orthologs in B. napus remains unclear. Six BnTFL1 paralogs in the genome of the B. napus inbred line ‘K407’ showed steadily increasing expression during vernalization. CRISPR/Cas-induced mutagenesis of up to four BnTFL1 paralogs resulted in early flowering and alteration of plant architecture, whereas seed yield was not altered in BnTFL1 single, double, or triple mutants. Six BnTFL1 paralogs, but not BnaA02.TFL1, showed an additive and conserved effect on regulating flowering time, total and terminal flower number, and plant architecture. BnaA10.TFL1 regulates flower development by interacting with BnaA08.FD through the protein BnaA05.GF14nu, resulting in the transcriptional repression of floral integrator and floral meristem identity genes. These findings about the regulatory network controlling flower development and plant architecture present a promising route to modifying these traits in B. napus.

A large amount of genome-wide association study (GWAS) panels together with quantitative-trait locus (QTL) information associated with breeding-targeted traits have been described in wheat (Triticum aestivum L.). However, the application of mapping results from a GWAS panel to conventional wheat breeding remains a challenge. In this study, we first report a general genetic map which was constructed from 44 published linkage maps. It permits the estimation of genetic distances between any two genetic loci with physical map positions, thereby unifying the linkage relationships between QTL, genes, and genomic markers from multiple genetic populations. Second, we describe QTL mapping in a wheat GWAS panel of 688 accessions, identifying 77 QTL associated with 12 yield and grain-quality traits. Because these QTL have known physical map positions, they could be mapped onto the general map. Finally, we present a design approach to wheat breeding by using known QTL information and computer simulation. Potential crosses between parents in the GWAS panel may be evaluated by the relative frequency of the target genotype, trait correlations in simulated progeny populations, and genetic gain of selected progenies. It is possible to simultaneously improve yield and grain quality by suitable parental selection, progeny population size, and progeny selection scheme. Applying the design approach will allow identifying the most promising crosses and selection schemes in advance of the field experiment, increasing predictability and efficiency in wheat breeding.

Rice is one of the three most important food crops in the world. Increasing rice yield is an effective way to ensure food security. Grain size is a key factor affecting rice yield; however, the genetic and molecular mechanisms regulating grain size have not been fully investigated. In this study, we identified a rice mutant, wide grain 4-D (wg4-D), that exhibited a significant increase in grain width and a decrease in grain length. Histological analysis demonstrated that WG4 affects cell expansion thereby regulating grain size. MutMap-based gene mapping and complementary transgenic experiments revealed that WG4 encodes an alpha-tubulin, OsTubA1. A SNP mutation in WG4 affected the arrangement of cortical microtubules and caused a wide-grain phenotype. WG4 is located in nuclei and cytoplasm and expressed in various tissues. Our results provide insights into the function of tubulin in rice and identifies novel targets the regulation of grain size in crop breeding.

Sugarcane mosaic virus (SCMV) is the main etiological agent of sugarcane mosaic disease, which affects sugarcane and other grass crops. Despite the extensive characterization of quantitative trait loci controlling resistance to SCMV in maize, the genetic basis of this trait in sugarcane is largely unexplored. Here, a genome-wide association study was performed and machine learning coupled with feature selection was used for genomic prediction of resistance to SCMV in a diverse sugarcane panel. Nine single-nucleotide polymorphisms (SNPs) explained up to 29.9% of the observed phenotypic variance and a 73-SNP set predicted resistance with high accuracy, precision, recall, and F1 scores (the harmonic mean of precision and recall). Both marker sets were validated in additional sugarcane genotypes, in which the SNPs explained up to 23.6% of the phenotypic variation and predicted resistance with a maximum accuracy of 69.1%. Synteny analyses suggested that the gene responsible for the majority of SCMV resistance in maize is absent in sugarcane, explaining why this major resistance source has not been identified in this crop. Finally, using sugarcane RNA-Seq data, markers associated with resistance to SCMV were annotated, and a gene coexpression network was constructed to identify the predicted biological processes involved in resistance. This network allowed the identification of candidate resistance genes and confirmed the involvement of stress responses, photosynthesis, and the regulation of transcription and translation in resistance to SCMV. These results provide a practical marker-assisted breeding approach for sugarcane and identify target genes for future studies of SCMV resistance.

More than 170 years after causing the potato famine in Ireland, late blight is still considered one of the most devastating crop diseases. Commercial potato breeding efforts depend on natural sources of resistance to protect crops from the rapidly evolving late blight pathogen, Phytophthora infestans. We have identified and mapped a novel broad-spectrum disease resistance gene effective against P. infestans from the wild, diploid potato species Solanum bulbocastanum. Diagnostic resistance gene enrichment sequencing (dRenSeq) was used to confirm the uniqueness of the identified resistance. RenSeq and GenSeq-based mapping of the resistance, referred to as Rpi-blb4, alongside recombinant screening, positioned the locus responsible for the resistance to potato chromosome 5. The interval spans approximately 2.3 Mb and corresponds to the DM reference genome positions of 11.25 and 13.56 Mb.

Nuclear factor Y (NF-Y), a group of conserved transcription-factor complexes that consist of NF-YA, B, and C subunits, is essential for developmental regulation and for responses to environmental changes in eukaryotes. We previously found that some NF-Y genes, such as OsNF-YA8, were expressed specifically in the endosperm of rice. In the present study, overexpression of OsNF-YA8 in rice resulted in reduced plant height due to suppressed cell elongation in internodes. Gibberellin (GA) biosynthetic genes, including OsCPS1, OsGA20ox1, and OsGA20ox2, were down-regulated. OsNF-YA8 bound to the promoters of these genes to repress their expression. Endogenous GA content was decreased in OsNF-YA8 overexpressors, whose dwarf phenotype could be partially rescued by exogenous GA treatment. The findings suggested that ectopic expression of OsNF-YA8 causes defective GA biosynthesis in vegetative stage. Heading date in OsNF-YA8 overexpressors was delayed, especially under short-day conditions. OsNF-YA8 bound to the promoter of Heading Date 3a (Hd3a), the florigen gene in rice, to negatively regulate flowering. Either ectopic activation or knockout of OsNF-YA8 impaired seed development, as indicated by reduced seed size and increased grain chalkiness. These results suggest that ectopic expression of the endosperm-specific OsNF-YA8 in rice disrupts both vegetative and reproductive development.

Rice yield stability is a breeding goal, particularly for short-growth duration rice, but its underlying mechanisms remain unclear. In an attempt to identify the relationship between yield stability and source–sink characteristics in short-growth duration rice, a field experiment was conducted at three sites (Yueyang, Liuyang, and Hengyang) in 2021 and 2022. This study compared yield, yield components, source–sink characteristics, and their stability between two stable-yielding short-growth duration rice cultivars, Zhongzao 39 (Z-39) and Lingliangyou 268 (L-268), and two unstable-yielding short-growth duration rice cultivars, Zhongjiazao 17 (Z-17) and Zhuliangyou 819 (Z-819). The stability of agronomic parameters was represented by the coefficient of variation (CV). The respective CVs of yield in Z-17, Z-819, Z-39, and L-268 were 10.2%, 10.1%, 4.5%, and 5.7% in 2021 and 19.7%, 15.0%, 5.4%, and 6.5% in 2022. The respective CVs of grain weight were 6.3%, 5.7%, 3.4%, and 4.5% in Z-17, Z-819, Z-39, and L-268 in 2021, and 8.1%, 6.3%, 1.5%, and 0.8% in 2022. The mean source capacity per spikelet and pre-heading non-structural carbohydrate reserves per spikelet (NSC_pre) were 7%–43% and 7%–72% lower in Z-819 and Z-17 than in L-268 and Z-39 in 2021 and 2022. The mean quantum yield of photosystem II photochemistry of leaf, leaf area index, and specific leaf weight of L-268 and Z-39 were higher than those of Z-819 and Z-17 at the heading stage. This study suggests that high NSC_pre, caused by great leaf traits before heading, increases source capacity per spikelet and its stability, thereby increasing the stability of grain weight and yield. Increasing NSC_pre is critical for achieving grain weight and yield stability in short-growth duration rice.