Molecular Breeding最新文献

Citrus canker is a devastating disease caused by Xanthomonas citri subsp. citri (Xcc), which secretes the effector PthA4 into host plants to trigger transcription of the susceptibility gene CsLOB1, resulting in pustule formation. However, the molecular mechanism underlying CsLOB1-mediated susceptibility to Xcc remains elusive. This study identified CsCEL20 as a target gene positively regulated by CsLOB1. Cell expansion and cell wall degradation were observed in sweet orange leaves after Xcc infection. A total of 69 cellulase genes were retrieved within the Citrus sinensis genome, comprising 40 endoglucanase genes and 29 glucosidase genes. Transcriptomic analysis revealed that expression levels of CsCEL8, CsCEL9, CsCEL20, and CsCEL26 were induced by Xcc invasion in sweet orange leaves, but not in the resistant genotype Citron C-05. Among them, CsCEL20 exhibited the highest expression level, with an over 430-fold increase following Xcc infection. Additionally, RT-qPCR analysis confirmed that CsCEL20 expression was induced in susceptible genotypes (Sweet orange, Danna citron, Lemon) upon Xcc invasion, but not in resistant genotypes (Citron C-05, Aiguo citron, American citron). A Single-Nucleotide Polymorphism (SNP) at -423 bp was identified in the CEL20 promoters and exhibits a difference between eight susceptible citrus genotypes and three resistant ones. Moreover, CsCEL20 expression was upregulated in CsLOB1-overexpression transgenic lines compared to the wild type. Dual-luciferase reporter assays indicated that CsLOB1 can target the -505 bp to -168 bp region of CsCEL20 promoter to trans-activate its expression. These findings suggest that CsCEL20 may function as a candidate gene for citrus canker development and may be a promising target for biotechnological breeding of Xcc-resistant citrus genotypes.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01531-3.

Increasing planting density is one of the most important strategies for generating higher maize yields. Moderate leaf rolling decreases mutual shading of leaves and increases the photosynthesis of the population and hence increases the tolerance for high-density planting. Few genes that control leaf rolling in maize have been identified, however, and their applicability for breeding programs remains unclear. Here we identified a maize abaxially rolled leaf1 (arl1) mutant with extreme abaxially rolled leaves and found that the size of the bulliform cells within the adaxial leaf blade surface increased in the arl1 mutant. Bulk segregation analysis mapping in an F₂ population derived from a single cross between arl1 and inbred line Gui18421 with normal leaves identified the arl1 locus on chromosome 2. Sequential fine-mapping delimited the arl1 locus to a 233.56-kb genomic interval containing three candidate genes. Sequence alignment between arl1 and Gui18421 identified an 8-bp insertion in the coding region of Zm00001eb082500, which led to a frame shift causing premature transcription termination in arl1 mutant. Meanwhile, both deep sequencing and Sanger sequencing showed that Zm00001eb082520 was present in Gui18421 but was absent in arl1. A pair of near isogenic lines (NILs) carrying the Gui18421 allele (NIL^Gui18421) and the arl1 allele (NIL ^arl1 ) were developed, and the leaves of NIL ^arl1 plants had greater light transmission and photosynthetic rate in the middle and lower canopy than did those of NIL^Gui18421 plants under high-density planting. Furthermore, NIL ^arl1 had a higher seed setting rate, more kernels per ear, and an increased kernel weight per ear than NIL^Gui18421, and the grain yield of NIL ^arl1 was not affected as the planting density increased, suggesting that the arl1 locus can be used for genetic improvement of high-density planting tolerance. Taken together, the identification of arl1 and evaluation of yield-related traits for NIL^Gui18421 and NIL ^arl1 provide an excellent target for future maize improvement.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01534-0.

Tofu is a popular soybean (Glycine max (L.) Merr.) food with a long tradition in Asia and rising popularity worldwide, including Central Europe. Due to the labour-intensive phenotyping procedures, breeding for improved tofu quality is challenging. Therefore, our objective was to unravel the genetic architecture of traits relevant for tofu production in order to assess the potential of marker-assisted selection and genomic selection in breeding for these traits. To this end, we performed QTL mapping with 188 genotypes from a biparental mapping population. The population was evaluated in a two-location field trial, and tofu was produced in the laboratory to evaluate tofu quality. We identified QTL for all investigated agronomic and quality traits, each explaining between 6.40% and 27.55% of the genotypic variation, including the most important tofu quality traits, tofu yield and tofu hardness. Both traits showed a strong negative correlation (r = -0.65), and consequently a pleiotropic QTL on chromosome 10 was found with opposite effects on tofu hardness and tofu weight, highlighting the need to balance selection for both traits. Four QTL identified for tofu hardness jointly explained 68.7% of the genotypic variation and are possible targets for QTL stacking by marker-assisted selection. To exploit also small-effect QTL, genomic selection revealed moderate to high mean prediction accuracies for all traits, ranging from 0.47 to 0.78. In conclusion, inheritance of tofu quality traits is highly quantitative, and both marker-assisted selection and genomic selection present valuable tools to advance tofu quality by soybean breeding.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01529-x.

Black rice has a long history of cultivation in Asia especially China. As a whole grain, black rice is rich in diverse nutrients including proteins, vitamins, amino acids, minerals, unsaturated fatty acids, dietary fibers, alkaloids, carotenes, phenolic compounds, and anthocyanins, in addition to starch. Many studies have demonstrated a range of health-promoting effects by black rice, which has greatly attracted the attention of consumers. However, the production and consumption of black rice has been low mostly because of its poor cooking and eating quality. To address this problem, the first is a need for technology to evaluate the cooking and eating quality of black rice. In this study, we investigated the feasibility of using Rice Taste Evaluation System (RTES) as a proxy approach to eating and cooking quality evaluation of whole grain black rice (WGBR). Totally, 775 black rice samples obtained from 363 accessions harvested from field planting were evaluated both with sensory evaluation by panelists and with RTES consisting of a cooked rice taste analyzer and a hardness and stickiness meter, which produced 8 characteristic parameters. We obtained highly significant correlation (R ²  = 0.867, P < 2.2 × 10^-16) between sensory test scores and RTES values by multiple linear regression equation based on the selected variables, which was validated with just as high correlation, indicating that the RTES can provide equivalent results the sensory test. With the efficiency of this equipment, the RTES can provide a convenient and accurate tool for high throughput evaluation of cooking and eating quality of WGBR for breeding and other usages.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01535-z.

The phenotypes of chili pepper (Capsicum annuum) fruit are sometimes characterized by having either smooth or wrinkled surfaces, both of which are commercially important. However, as the inheritance patterns and responsible loci have not yet been identified, it is difficult to control fruit surface traits in conventional chili pepper breeding. To obtain new insights into these aspects, we attempted to clarify the genetic regulation mechanisms responsible for the wrinkled surface of fruit from the Japanese chili pepper 'Shishito' (C. annuum). First, we investigated the segregation patterns of fruit-surface wrinkling in F₂ progeny obtained from crosses between the C. annuum cultivars 'Shishito' and 'Takanotsume', the latter of which has a smooth fruit surface. The F₂ progeny exhibited a continuous variation in the level of wrinkling, indicating that the wrinkled surface in 'Shishito' was a quantitative trait. To identify the responsible loci, we performed quantitative trait locus (QTL) analysis of the F₂ progeny using restriction site-associated DNA sequencing data obtained in our previous study. The results showed that two significant QTLs (Wr11 and Wr12) were newly detected on chromosome 11 and 12, which explained 17.5 and 66.0% of the genetic variance, respectively. We then investigated the genetic effects of these QTLs using molecular markers. The findings showed that the levels of wrinkling in the F₂ progeny could mostly be explained by the independent additive effects of the 'Shishito' allele in Wr12. This locus was therefore considered to be a useful genomic region for controlling fruit surface traits in the chili pepper.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01528-y.

Corn is a widely grown cereal crop that serves as a model plant for genetic and evolutionary studies. However, the heterosis pattern of sweet corn remains unclear. Here, we analysed the genetic diversity and population structure of 514 sweet corn inbred lines and 181 field corn inbred lines. The population structure study enabled the classification of sweet corn into four groups: temperate sweet corns 1 and 2, tropical sweet corn, and subtropical sweet corn, in addition to the temperate and tropical field corn groups. Temperate sweet corn groups 1 and 2 were merged into the temperate sweet corn cluster in the phylogenetic trees. Principal component analysis divided sweet corn into four groups: temperate groups 1 and 2, tropical, and subtropical. Sweet corn exhibited lower levels of genetic diversity, polymorphism information content, and minor allele frequency than field corn. The average genetic distances and differentiation coefficients between inbreds within each sweet corn group were lower than those within field corn groups, indicating a relatively narrow genetic base in sweet corn. Taken together, the 514 sweet corn inbred lines can be divided into four groups: temperate 1, temperate 2, tropical, and subtropical. The classification of sweet corn groups in this study provides a reference for the breeding of sweet corn.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01533-1.

Apple is a crucial economic product extensively cultivated worldwide. Its production and quality are closely related to the floral transition, which is regulated by intricate molecular and environmental factors. Nuclear factor Y (NF-Y) is a transcription factor that is involved in regulating plant growth and development, with certain NF-Ys play significant roles in regulating flowering. However, there is little information available regarding NF-Ys and their role in apple flowering development. In the present study, 51 NF-Y proteins were identified and classified into three subfamilies, including 11 MdNF-YAs, 26 MdNF-YBs, and 14 MdNF-YCs, according to their structural and phylogenetic features. Further functional analysis focused on MdNF-YB18. Overexpression of MdNF-YB18 in Arabidopsis resulted in earlier flowering compared to the wild-type plants. Subcellular localization confirmed MdNF-YB18 was located in the nuclear. Interaction between MdNFY-B18 and MdNF-YC3/7 was demonstrated through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Yeast one-hybrid (Y1H) and the dual-luciferase reporter assays showed MdNF-YB18 could bind the promoter of MdFT1 and activate its expression. Moreover, this activation was enhanced with the addition of MdNF-YC3 and MdNF-YC7. Additionally, MdNF-YB18 also could interact with MdCOLs (CONSTANS Like). This study lays the foundation for exploring the functional traits of MdNF-Y proteins, highlighting the crucial role of MdNF-YB18 in activating MdFT1 in Malus.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01524-2.

Seed size is an economically important trait that directly determines the seed yield in soybean. In the current investigation, we used an integrated strategy of linkage mapping, association mapping, haplotype analysis and candidate gene analysis to determine the genetic makeup of four seed size-related traits viz., 100-seed weight (HSW), seed area (SA), seed length (SL), and seed width (SW) in soybean. Linkage mapping identified a total of 23 quantitative trait loci (QTL) associated with four seed size-related traits in the F₂ population; among them, 17 were detected as novel QTLs, whereas the remaining six viz., qHSW3-1, qHSW4-1, qHSW18-1, qHSW19-1, qSL4-1 and qSW6-1 have been previously identified. Six out of 23 QTLs were major possessing phenotypic variation explained (PVE) ≥ 10%. Besides, the four QTL Clusters/QTL Hotspots harboring multiple QTLs for different seed size-related traits were identified on Chr.04, Chr.16, Chr.19 and Chr.20. Genome-wide association study (GWAS) identified a total of 62 SNPs significantly associated with the four seed size-related traits. Interestingly, the QTL viz., qHSW18-1 was identified by both linkage mapping and GWAS, and was regarded as the most stable loci regulating HSW in soybean. In-silico, sequencing and qRT-PCR analysis identified the Glyma.18G242400 as the most potential candidate gene underlying the qHSW18-1 for regulating HSW. Moreover, three haplotype blocks viz., Hap2, Hap6A and Hap6B were identified for the SW trait, and one haplotype was identified within the Glyma.18G242400 for the HSW. These four haplotypes harbor three to seven haplotype alleles across the association mapping panel of 350 soybean accessions, regulating the seed size from lowest to highest through intermediate phenotypes. Hence, the outcome of the current investigation can be utilized as a potential genetic and genomic resource for breeding the improved seed size in soybean.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01525-1.

Brassica napus, a globally significant oilseed crop, exhibits a wide distribution across diverse climatic zones. B. napus is being increasingly susceptible to distinct diseases, such as blackleg, clubroot and sclerotinia stem rot, leading to substantial reductions in yield. Nucleotide-binding site leucine-rich repeat genes (NLRs), the most pivotal family of resistance genes, can be effectively harnessed by identifying and uncovering their diversity to acquire premium disease-resistant gene resources. Here, we collected the genomes of 23 accessions and established the first comprehensive pan-NLRome in B. napus by leveraging multiple genomic resources. We observe significant variation in the number of NLR genes across different B. napus accessions, ranging from 189 to 474. Notably, TNL (TIR-NBS-LRR) genes constitute approximately half of the total count, indicating their predominant presence in B. napus. The number of NLRs in the C subgenome is significantly higher than that in the A subgenome, and chromosome C09 exhibits the highest density of NLR genes with featuring multiple NLR clusters. Domain analysis reveals that the integrated domains significantly enhance the diversity of NLRs, with B3 DNA binding, VQ, and zinc fingers being the most prevalent integrated domains. Pan-genomic analysis reveals that the core type of NLR genes, which is present in most accessions, constitutes approximately 58% of the total NLRs. Furthermore, we conduct a comparative analysis of the diversity of NLR genes across distinct ecotypes, leading to the identification of ecotype-specific NLRs and their integrated domains. In conclusion, our study effectively addresses the limitations of a single reference genome and provides valuable insights into the diversity of NLR genes in B. napus, thereby contributing to disease resistance breeding.

Male sterility is an important trait for breeding and for the seedless fruit production in citrus. We identified one seedling which exhibiting male sterility and seedlessness (named ms1 hereafter), from a cross between two fertile parents, with sour orange (Citrus aurantium) as seed parent and Ponkan mandarin (Citrus reticulata) as pollen parent. Analysis using pollen viability staining, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed that the mature pollen of the ms1 was aborted, displaying collapse and deformity. Further cytological analysis identified the abnormal formation of monad, dyad, and tetrad instead of the normal tetrad formation, leading to meiotic failure in the seedless hybrid. By comparative transcript profiling of meiotic anther of fertile and sterile hybrids, we observed significant downregulation of CYCA1;2 (TAM) and OSD1 genes in the hybrid, which known to control the transition from meiosis I to meiosis II in plants. These results indicated abnormal meiosis led to the male sterility of the seedless hybrid and that the decreased activities of kinases and cyclins may associated with the failure of the transition of meiosis I to meiosis II during anthers development.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01521-5.