Search

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]

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]