Search

Background: Chestnut blight, one of the most serious branch diseases in Castanea caused by Cryphonectria parasitica, which has ravaged across American chestnut and most of European chestnut since the early twentieth century. Interestingly, the Chinese chestnut is strongly resistant to chestnut blight, shedding light on restoring the ecological status of Castanea plants severely affected by chestnut blight. To better explore the early defense of Chinese chestnut elicited in response to C. parasitica, the early stage of infection process of C. parasitica was observed and RNA sequencing-based transcriptomic profiling of responses of the chestnut blight-resistant wild resource 'HBY-1' at 0, 3 and 9 h after C. parasitica inoculation was performed. Results: First, we found that 9 h was a critical period for Chinese chestnut infected by C. parasitica, which was the basis of further study on transcriptional activation of Chinese chestnut in response to chestnut blight in the early stage. In the transcriptome analysis, a total of 283 differentially expressed genes were identified between T9 h and Mock9 h, and these DEGs were mainly divided into two clusters, one of which was metabolism-related pathways including biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, amino sugar and nucleotide sugar metabolism, and photosynthesis; the other was related to plant-pathogen interaction and MAPK signal transduction. Meanwhile, the two clusters of pathways could be connected through junction among phosphatidylinositol signaling system, phytohormone signaling pathway and α-Linolenic acid metabolism pathway. It is worth noting that genes associated with JA biosynthesis and metabolic pathway were significantly up-regulated, revealing that the entire JA metabolic pathway was activated in Chinese chestnut at the early stage of chestnut blight infection. Conclusion: We identified the important infection nodes of C. parasitica and observed the morphological changes of Chinese chestnut wounds at the early stage of infection. In response to chestnut blight, the plant hormone and MAPK signal transduction pathways, plant-pathogen interaction pathways and metabolism-related pathways were activated at the early stage. JA biosynthesis and metabolic pathway may be particularly involved in the Chinese chestnut resistance to chestnut blight. These results contributes to verifying the key genes involved in the resistance of Chinese chestnut to C. parasitica. [ABSTRACT FROM AUTHOR]

Background: Chestnut blight, one of the most serious branch diseases in Castanea caused by Cryphonectria parasitica, which has ravaged across American chestnut and most of European chestnut since the early twentieth century. Interestingly, the Chinese chestnut is strongly resistant to chestnut blight, shedding light on restoring the ecological status of Castanea plants severely affected by chestnut blight. To better explore the early defense of Chinese chestnut elicited in response to C. parasitica, the early stage of infection process of C. parasitica was observed and RNA sequencing-based transcriptomic profiling of responses of the chestnut blight-resistant wild resource 'HBY-1' at 0, 3 and 9 h after C. parasitica inoculation was performed. Results: First, we found that 9 h was a critical period for Chinese chestnut infected by C. parasitica, which was the basis of further study on transcriptional activation of Chinese chestnut in response to chestnut blight in the early stage. In the transcriptome analysis, a total of 283 differentially expressed genes were identified between T9 h and Mock9 h, and these DEGs were mainly divided into two clusters, one of which was metabolism-related pathways including biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, amino sugar and nucleotide sugar metabolism, and photosynthesis; the other was related to plant-pathogen interaction and MAPK signal transduction. Meanwhile, the two clusters of pathways could be connected through junction among phosphatidylinositol signaling system, phytohormone signaling pathway and α-Linolenic acid metabolism pathway. It is worth noting that genes associated with JA biosynthesis and metabolic pathway were significantly up-regulated, revealing that the entire JA metabolic pathway was activated in Chinese chestnut at the early stage of chestnut blight infection. Conclusion: We identified the important infection nodes of C. parasitica and observed the morphological changes of Chinese chestnut wounds at the early stage of infection. In response to chestnut blight, the plant hormone and MAPK signal transduction pathways, plant-pathogen interaction pathways and metabolism-related pathways were activated at the early stage. JA biosynthesis and metabolic pathway may be particularly involved in the Chinese chestnut resistance to chestnut blight. These results contributes to verifying the key genes involved in the resistance of Chinese chestnut to C. parasitica. [ABSTRACT FROM AUTHOR]

The plant cuticle is the outermost layer of the aerial organs and an important barrier against biotic and abiotic stresses. The climate varies greatly between the north and south of China, with large differences in temperature and humidity, but Chinese chestnut is found in both regions. This study investigated the relationship between the wax layer of chestnut leaves and environmental adaptation. Firstly, semi-thin sections were used to verify that there is a significant difference in the thickness of the epicuticular wax layer between wild chestnut leaves in northwest and southeast China. Secondly, a whole-genome selective sweep was used to resequence wild chestnut samples from two typical regional populations, and significant genetic divergence was identified between the two populations in the CmCER1-1, CmCER1-5 and CmCER3 genes. Thirty-four CER genes were identified in the whole chestnut genome, and a series of predictive analyses were performed on the identified CmCER genes. The expression patterns of CmCER genes were classified into three trends—upregulation, upregulation followed by downregulation and continuous downregulation—when chestnut seedlings were treated with drought stress. Analysis of cultivars from two resource beds in Beijing and Liyang showed that the wax layer of the northern variety was thicker than that of the southern variety. For the Y-2 (Castanea mollissima genome sequencing material) cultivar, there were significant differences in the expression of CmCER1-1, CmCER1-5 and CmCER3 between the southern variety and the northern one-year-grafted variety. Therefore, this study suggests that the CER family genes play a role in environmental adaptations in chestnut, laying the foundation for further exploration of CmCER genes. It also demonstrates the importance of studying the adaptation of Chinese chestnut wax biosynthesis to the southern and northern environments. [ABSTRACT FROM AUTHOR]

Castanea species have enormous potential for broad applications in the biomedical sciences and chemical wood industries. Due to the occurrence of fungal diseases, especially chestnut blight, the survival status of Castanea plants is seriously threatened. Castanea plants in China have natural tolerance to chestnut blight. This study investigated the genetic diversity and chestnut blight resistance of Castanea plants in China and searched for germplasm with high tolerance resistance. Cluster and population structure analysis revealed that wild Castanea plants in China could be divided into three groups with significant interspecific boundary, C. henryi var. omeiensis is located between C. mollissima and C. henryi var. henryi. The ABBA-BBAA test showed that significant gene introgression occurred between C. mollissima and C. henryi in Mount Emei, supporting the conclusion that C. henryi var. omeiensis as a natural hybrid resource. The results of disease resistance evaluation showed that the tolerance of wild C. mollissima to chestnut blight was the highest and significantly higher than that of wild C. henryi and C. seguinii. In particular, there is a strong association between disease tolerance in C. henryi var. omeiensis and the level of genetic introgression from C. mollissima. Then, the rIBD fragments of C. henryi var. omeiensis derived from C. mollissima were analyzed to reveal the source of disease resistance using whole genome resequencing data. A total of 203 rIBD segments containing 435 genes were identified. Finally, 41 candidate genes for chestnut blight resistance were selected through multiple omics. In conclusion, this study investigated a type of interspecific disease-resistant hybrid resources, identified a set of candidate genes for chestnut blight resistance, and provided new strategies for disease-resistant breeding of chestnut resources in the future. • The tolerance of wild Castanea including three species to chestnut blight in China was evaluated. • It was confirmed that C. henryi var. omeiensis was an interspecific hybrid with high tolerance to chestnut blight. • A total of 203 rIBD segments and 41 candidate disease resistance genes were identified to enable next-generation precision breeding of chestnuts. [ABSTRACT FROM AUTHOR]

There are many factors that affect the yield of Chinese chestnut (Castanea mollissima), with single nut weight (SNW) being one of the most important. Leaf length is also related to Chinese chestnut yield. However, the genetic architecture and gene function associated with Chinese chestnut nut yield have not been fully explored. In this study, we performed genotyping by sequencing 151 Chinese chestnut cultivars, followed by a genome-wide association study (GWAS) on six horticultural traits. First, we analyzed the phylogeny of the Chinese chestnut and found that the Chinese chestnut cultivars divided into two ecotypes, a northern and southern cultivar group. Differences between the cultivated populations were found in the pathways of plant growth and adaptation to the environment. In the selected regions, we also found interesting tandemly arrayed genes that may influence Chinese chestnut traits and environmental adaptability. To further investigate which horticultural traits were selected, we performed a GWAS using six horticultural traits from 151 cultivars. Forty-five loci that strongly associated with horticultural traits were identified, and six genes highly associated with these traits were screened. In addition, a candidate gene associated with SNW, APETALA2 (CmAP2), and another candidate gene associated with leaf length (LL), CRYPTOCHROME INTERACTING BASIC HELIX-LOOP-HELIX 1 (CmCIB1), were verified in Chinese chestnut and Arabidopsis (Arabidopsis thaliana). Our results showed that CmAP2 affected SNW by negatively regulating cell size. CmCIB1 regulated the elongation of new shoots and leaves by inducing cell elongation, potentially affecting photosynthesis. This study provided valuable information and insights for Chinese chestnut breeding research. A genome-wide association study on six horticultural traits from 151 Chinese chestnut cultivars reveals important genes related to leaf and shoot elongation and nut weight. [ABSTRACT FROM AUTHOR]

Background The Chinese chestnut (Castanea mollissima) is widely cultivated in China for nut production. This plant also plays an important ecological role in afforestation and ecosystem services. To facilitate and expand the use of C. mollissima for breeding and its genetic improvement, we report here the whole-genome sequence of C. mollissima. Findings We produced a high-quality assembly of the C. mollissima genome using Pacific Biosciences single-molecule sequencing. The final draft genome is ∼785.53 Mb long, with a contig N50 size of 944 kb, and we further annotated 36,479 protein-coding genes in the genome. Phylogenetic analysis showed that C. mollissima diverged from Quercus robur , a member of the Fagaceae family, ∼13.62 million years ago. Conclusions The high-quality whole-genome assembly of C. mollissima will be a valuable resource for further genetic improvement and breeding for disease resistance and nut quality. [ABSTRACT FROM AUTHOR]