Fig 3 - available via license: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Content may be subject to copyright.
Source publication
Apple Glomerella leaf spot (GLS) is a destructive fungal disease that damages apple leaves during the summer in China. Breeding new disease-resistant varieties is considered to be the best way of controlling GLS. A genetic study of resistance to Glomerella leaf spot (GLS) in apple was conducted by using four F1 hybrid groups (‘Fuji’ × ‘Golden Delic...
Similar publications
Background. Soybean (Glycine max (L.) Merr.) gradually becomes one of the leading legume crops in Kazakhstan. The area under soybeans in the country has been increasing annually and requires the development of adapted cultivars with a higher yield, improved quality characters, and resistance to emerging fungal diseases. The enlargement of the crop’...
Citations
... Isolates isolated from the GLS lesions caused GLS lesions on both the apple fruits and leaves ( Table 3). The isolates of C. aenigma (F12PGXY03, W12PGYXY15) and C. fructicola (F12PGSQ0503, W12PGYSQ06) were pathogenic on the leaves and fruits of Gala apples, but non-pathogenic on Fuji apple leaves or fruits in the non-wounded inoculation ( Figure 5), which is in accordance with the observation that Fuji apples are resistant to GLS disease [61]. Table 3. Pathogenicity test of selected isolates on apple leaves. ...
Bitter rot and Glomerella leaf spot (GLS) of apples, caused by Colletotrichum species, are major diseases of apples around the world. A total of 98 isolates were obtained from apple fruits with bitter rot, and 53 isolates were obtained from leaves with leaf spot in the primary apple production regions in China. These isolates were characterized morphologically, and five gene regions (ITS, ACT, GAPDH, CHS-1 and TUB2) were sequenced for each isolate. A phylogenetic analysis, combined with a comparison of the morphological, cultural and pathogenic characters, sorted bitter rot isolates into six species: C. alienum, C. fructicola, C. gloeosporioides sensu stricto, C. nymphaeae, C. siamense and one new species, C. orientalis Dandan Fu & G.Y. Sun. Among these, C. siamense was the predominant pathogen associated with bitter rot. Isolates from leaf spot were identified as two species, C. aenigma and C. fructicola. This is the first report of C. orientalis as an apple bitter rot pathogen worldwide, and the results provide important insights into the diversity of Colletotrichum species in China.
... GLS mainly occurred in some major apple cultivars, such as 'Gala' and 'Golden Delicious'. Some other widely cultured apple cultivars, such as 'Fuji' and its derivative cultivars, exhibited high resistance to GLS [3]. GLS was first reported in the United States in 1970, but it did not come to attention for the less damage to the apple production [4]. ...
... Our previous research has reported that apple GLS resistance is controlled by a recessive single gene on chromosome 15 [3], and the resistance gene loci (Rgls) are located between SNP 4208 and SNP 4257 , as determined by high-resolution melting (HRM) technique [21]. However, the major recessive gene has not been cloned. ...
... KASP, HRM, and PCR sequencing revealed SNP 7309212 difference between resistant and susceptible apple cultivars ( Figure 1C,D; Tables S3-S5). SNP 7309212 in the parents 'Fuji' and 'Golden delicious' showed AA and AT, respectively, whereas in the hybrid F1, homozygous AA only existed in the resistant apple, while heterozygous AT and homozygous TT were only present in the susceptible apple varieties, which is consistent with previous reports that GLS resistance was controlled by recessive single gene [3,21]; thus, we clearly found a strong association between the MdTNL1 and GLS. ...
Glomerella leaf spot (GLS), caused by the fungus Colletotrichum fructicola, is one of the most devastating apple diseases. Our previous study reported that the GLS resistance locus was defined on the chromosome 15 region. Here, we further found a single-nucleotide polymorphism (SNP) site (SNP7309212) in the GLS resistance that was able to distinguish resistant cultivars (lines) from susceptible ones. On the basis of the SNP site, we cloned a TNL gene from the GLS resistant locus and named it MdTNL1 (NCBI Accession Number: ON402514). This gene contains a toll/interleukin-1 receptor transmembrane domain (TIR), nucleotide-binding sites (NBS), and leucine-rich repeat (LRR) domain. Subcellular location indicated that MdTNL1 was expressed in the nucleus and cell membrane. Ectopic overexpression of MdTNL1 in Nicotiana benthamiana caused cell death. We further demonstrated allelic polymorphisms in MdTNL1. It is noteworthy that NBS and LRR domains of the MdTNL1 protein serve as the repository for generating allelic diversity. Quantitative real-time PCR (qRT-PCR) assay revealed that MdTNL1 was highly expressed in resistant apple cultivar ‘Fuji’ after inoculation with C. fructicola, whereas susceptible cultivar ‘Golden Delicious’ exhibited low expression after inoculation. Over-expression of MdTNL1-1 in susceptible apple fruits and leaves improved disease resistance, while in ‘Orin’ calli, silencing the MdTNL1-1 gene conversely decreased GLS resistance. In conclusion, we identified a GLS associated with SNP7309212 and demonstrated that a TIR-NBS-LRR gene MdTNL1-1 positively regulates GLS resistance in apple.
... Fuji apple is resistant whereas certain cultivars, including 'Gala', 'Golden Delicious', and 'Jonathan', are highly susceptible (W. . Genetic analysis showed that a single recessive genetic locus controls GLS resistance in Fuji apple (Liu et al. 2016). ...
Apples are grown worldwide, and consuming fresh apple fruit is associated with many health benefits. China produces about half of the world’s apple supply. However, apple growing in China differs sharply from that in western countries in terms of the prevalent diseases and corresponding management strategies. For instance, family-owned small-scale orchards dominate China’s apple industry, and manual bagging of fruit has been a long-standing practice for controlling fruit diseases. In recent years, rural labor shortages have been increasingly challenging the traditional production system, and China’s apple industry is experiencing a rapid transition to much larger-scale enterprises featuring high-density orchards with advanced automation and mechanization. Associated with this transition are new challenges and grower demands that are changing the face of apple disease management. This Feature Article summarizes the ongoing transformation of China’s apple industry in the context of sustainable disease management.
... The resistance of some apple cultivars (descendants from the 'Red Delicious' group) to Glomerella leaf spot has proved to be durable [18] and is governed by a single recessive gene [19]. Molecular and genetic mechanisms controlling resistance in plants have been extensively studied and in this context, arabidopsis and apple can be helpful to understand the mechanisms involved in NHR against Colletotrichum spp. ...
Non-host resistance (NHR) describes the immunity state of plant species against non-adapted pathogen species and has been considered the most durable and effective form of plant resistance in nature. The objective of this work was to study the non-host resistance mechanisms involved in Arabidopsis thaliana and Malus domestica against Colletotrichum fructicola and Colletotrichum higginsianum, respectively. For this, the development of preinfective
structures of Colletotrichum species, hypersensitivity responses and callose accumulation were monitored in host and non-host plants. Conidial germination and appressorial formation of Colletotrichum were affected on non-host leaf surfaces. Conidial germination and appressorial melanization of both Colletotrichum species occurred in a faster manner on arabidopsis than on apple leaves. On apple leaves, appressoria of C. higginsianum became more pedicelate, while on its host (arabidopsis) they were typically sessile. Hypersensitive response (HR) and appressorium-associated HR occurred at low frequency in epidermal cells of both plants, and no relationship could be established with NHR. Callose accumulation was significantly higher in inoculated nonhost plants, mainly at attempted entry sites of Colletotrichum. Our results demonstrate that the mechanisms of
NHR involved in this heterologous interaction were associated to pre-invasive events as demonstrated by the changes in development of preinfective structures and the accumulation of papillary callose at sites of penetration attempts.
... In China, the varieties 'Golden Delicious', 'Gala', and 'Qinguan' are highly susceptible to GLS, whereas 'Fuji' and 'Red Star' are resistant. In apple, resistance to GLS is controlled by a single recessive gene 6 , and the location of a GLS resistance gene locus (R gls ) has been identified by bulked segregant analysis (BSA) 7,8 . ...
... To date, research regarding GLS of apple has mainly focused on isolating and identifying the pathogen 18 , environmental conditions affecting infection and spread 1 , the disease mechanism 19 , control methods 3 , and genetic mapping of GLS resistance gene loci [6][7][8] . However, little is known about the molecular mechanism underlying the plant's response to GLS infection. ...
... S2 and S3; Table S2). These data verified that resistance to GLS is controlled by a single recessive gene in apple and indicated the genotypes 'Golden Delicious', 'Hanfu', 'Yueshuai', and '62-45' to be Rr, Rr, Rr, and RR, respectively [6][7][8] . ...
Glomerella leaf spot (GLS) of apple (Malus×domestica Borkh.), caused by Glomerella cingulata, is an emerging fungal epidemic threatening the apple industry. Little is known about the molecular mechanism underlying resistance to this devastating fungus. In this study, high-throughput sequencing technology was used to identify microRNAs (miRNAs) involved in GLS resistance in apple. We focused on miRNAs that target genes related to disease and found that expression of a novel miRNA, Md-miRln20, was higher in susceptible apple varieties than in resistant ones. Furthermore, its target gene Md-TN1-GLS exhibited the opposite expression pattern, which suggested that the expression levels of Md-miRln20 and its target gene are closely related to apple resistance to GLS. Furthermore, downregulation of Md-miRln20 in susceptible apple leaves resulted in upregulation of Md-TN1-GLS and reduced the disease incidence. Conversely, overexpression of Md-miRln20 in resistant apple leaves suppressed Md-TN1-GLS expression, with increased disease incidence. We demonstrated that Md-miRln20 negatively regulates resistance to GLS by suppressing Md-TN1-GLS expression and showed, for the first time, a crucial role for miRNA in response to GLS in apple.
... Cultivars as Golden Delicious and their descendants such as cv. Galaxy or Cripps pink are highly susceptible, but others like Red Delicious and Fuji are highly resistant (Liu et al., 2016;Velho et al., 2015;Wang et al., 2015b). In Uruguay, commercial apple production is concentrated in the South where 22% of orchard trees belong to cvs. ...
Glomerella leaf spot (GLS) caused by Colletotrichum spp. is a destructive disease of apple restricted to a few regions worldwide. The distribution and evolution of GLS symptoms were observed for two years in Uruguay. The recurrent ascopore production on leaves and the widespread randomized distribution of symptoms throughout trees and orchard, suggest that ascospores play an important role in the disease dispersion. The ability of ascospores to produce typical GLS symptom was demonstrated by artificial inoculation. Colletotrichum strains causing GLS did not result in rot development, despite remaining alive in fruit lesions. Based on phylogenetic analysis of actin, β-tubulin and glyceraldehyde-3-phosphate dehydrogenase gene regions of 46 isolates, 25 from fruits and 21 from leaves, C. karstii was identified for the first time causing GLS in Uruguay and C. fructicola was found to be the most frequent (89%) and aggressive species. The higher aggressiveness of C. fructicola and its ability on to produce abundant fertile perithecia could help to explain the predominance of this species in the field.
... Dantas et al. (2009) reported that apple resistance to GLS was apparently controlled by a recessive allele at a single gene locus. We confirmed this in apple using four F 1 hybrid populations (BFuji^× Golden Delicious, Golden Delicious × Fuji, Gala × Fuji, and Fuji × BQF-2^) (Liu et al. 2016). We also constructed the first genetic mapping of a GLS resistance gene locus (R gls ) in apple with 11 SSR markers. ...
... The seedlings were planted in the field of the Fruit Research Station of Qingdao Agricultural University (Jiaozhou, Shandong Province, China) in 2009. In a previous study in which the shoots of the 207 F 1 individuals had been artificially inoculated using a conidial suspension of G. cingulata in an assay of detached leaves (Liu et al. 2016), 93 resistant individuals and 114 susceptible individuals were identified. DNA extraction and bulks of sample construction for BSA Genomic DNA was extracted using the CTAB method (Doyle 1987;Cullings 1992) from young leaf tissue of Golden Delicious, Fuji, and their F 1 plants. ...
Glomerella leaf spot (GLS) is a new fungal disease of apple that damages apple leaves mainly during the summer in China. For efficient GLS-resistant apple breeding by marker-assisted selection (MAS) and a better understanding of the molecular mechanisms of the resistance, it is important to find molecular markers that are tightly linked to GLS resistance genes and construct fine mapping. However, the development and selection of DNA markers are time-consuming and labor-intensive processes. Next-generation sequencing technology provides a powerful tool to overcome this limitation and is faster and more efficient in establishing the association of GLS resistance with molecular markers or searching for candidate genes. In this study, we report a method for rapid location of a GLS resistance gene locus (Rgls) in apple by whole genome re-sequencing technology coupled with bulked segregant analysis (BSA). A total of 3,399,950 single nucleotide polymorphisms (SNPs) were identified. Through the genome-wide comparison of SNP profiles between the resistant and the susceptible bulks constructed from F1 individuals derived from a cross between “Golden Delicious” and “Fuji,” the Rgls locus was identified on apple chromosome 15 between 2 and 5 Mb. In this region, eight SNP markers were validated using high resolution melting (HRM), and the fine genetic mapping of the eight markers was constructed. The Rgls locus was sandwiched by two flanking markers SNP4208 and SNP4257, with the recombination frequency of 0.97% (2/207). The marker SNP4236 co-segregated with Rgls. The physical size of the Rgls locus was estimated to be 49 kb. In this genetic interval, nine genes were predicted. Our study provides an effective method for rapid identification of genomic regions and development of the diagnostic markers for MAS. This strategy is potentially useful for other agronomic traits or plant species.
Apple Glomerella leaf spot (GLS) is an emerging fungal disease caused by Colletotrichum fructicola and other Colletotrichum species. These species are polyphyletic and it is currently unknown how these pathogens convergently evolved to infect apple. We generated chromosome‐level genome assemblies of a GLS‐adapted isolate and a non‐adapted isolate in C. fructicola using long‐read sequencing. Additionally, we resequenced 17 C. fructicola and C. aenigma isolates varying in GLS pathogenicity using short‐read sequencing. Genome comparisons revealed a conserved bipartite genome architecture involving minichromosomes (accessory chromosomes) shared by C. fructicola and other closely related species within the C. gloeosporioides species complex. Moreover, two repeat‐rich genomic regions (1.61 Mb in total) were specifically conserved among GLS‐pathogenic isolates in C. fructicola and C. aenigma . Single‐gene deletion of 10 accessory genes within the GLS‐specific regions of C. fructicola identified three that were essential for GLS pathogenicity. These genes encoded a putative non‐ribosomal peptide synthetase, a flavin‐binding monooxygenase and a small protein with unknown function. These results highlight the crucial role accessory genes play in the evolution of Colletotrichum pathogenicity and imply the significance of an unidentified secondary metabolite in GLS pathogenesis.
Glomerella leaf spot (GLS), caused by the fungal pathogen Colletotrichum fructicola, significantly threatens apple production. Some resistances to plant disease are mediated by the accumulation of nucleotide-binding site and leucine-rich repeat (NBS-LRR) proteins that are encoded by a major class of plant disease resistance genes (R genes). However, the R genes that confer resistance to GLS in apple remain largely unclear. Malus hupehensis YT521-B homology domain-containing protein 2 (MhYTP2) was identified as an N6 -methyladenosine RNA methylation (m6 A) modified RNA reader in our previous study. However, whether MhYTP2 binds to mRNAs without m6 A RNA modifications remains unknown. In this study, we discovered that MhYTP2 exerts both m6 A-dependent and -independent functions by analysing previously obtained RNA immunoprecipitation sequencing results. The overexpression of MhYTP2 significantly reduced the resistance of apple to GLS and down-regulated the transcript levels of some R genes whose transcripts do not contain m6 A modifications. Further analysis indicated that MhYTP2 binds to and reduces the stability of MdRGA2L mRNA. MdRGA2L positively regulates resistance to GLS by activating salicylic acid signalling. Our findings revealed that MhYTP2 plays an essential role in the regulation of resistance to GLS and identified a promising R gene, MdRGA2L, for use in developing apple cultivars with GLS resistance.
Glomerella leaf spot (GLS) caused by Glomerella cingulata is a newly emerging disease that results in severe defoliation and fruit spots in apples. In China, the compound of pyraclostrobin and tebuconazole was registered to control GLS in 2018 and has achieved excellent control efficiency. In this study, we showed that the high-level resistant isolates of G. cingulata to pyraclostrobin, caused by the point mutation at codon 143 (GGT→GCT, G143A) in cytochrome b gene, has appeared in apple orchards in Shandong province in 2020, and the resistance frequency was 4.8%. Based on the genotype of the resistant isolates, we developed a loop-mediated isothermal amplification (LAMP) assay for detection of the pyraclostrobin resistance. The LAMP assay was demonstrated to have good specificity, sensitivity and repeatability, and exhibited high accuracy to detect pyraclostrobin resistance in the field. This study reported the resistance status of GLS to pyraclostrobin in Shandong province, and developed a molecular tool for the detection of pyraclostrobin resistance, which is of practical significance for the scientific control of GLS.
