Genetic evidence that Chinese chestnut cultivars in Japan are derived from two divergent genetic structures that originated in China.

Sogo Nishio,Shuan Ruan,Yukie Takeuchi,Eiich Inoue,Norio Takada,Yutaka Sawamura,Shingo Terakami,Toshihiro Saito,Hidenori Sassa

doi:10.1371/journal.pone.0235354

Abstract

The Chinese chestnut (Castanea mollissima Bl.) was introduced into Japan about 100 years ago. Since then, a number of Chinese chestnut cultivars and Japanese-Chinese hybrid cultivars have been selected by farmers and plant breeders, but little information has been available about their origins and genetic relationships. A classification based on simple sequence repeat markers was conducted using 230 cultivars including Japanese chestnut (Castanea crenata Sieb. et Zucc.) cultivars originated in Japan, Japanese-Chinese hybrid cultivars, and Chinese chestnut cultivars originated in both Japan and China. First, a search for synonyms (cultivars with identical genotypes) revealed 23 synonym groups among the Chinese chestnut cultivars, and all but one cultivar from each synonym group was omitted from further analyses. Second, genetic structure analysis showed a clear division between Japanese and Chinese chestnut, and most of the Japanese and Chinese cultivars had a simple genetic structure corresponding to the expected species. On the other hand, most Japanese-Chinese hybrid cultivars had admixed genetic structure. Through a combination of parentage and chloroplast haplotype analyses, 16 of the 18 hybrid cultivars in this study were inferred to have parent-offspring relationships with other cultivars originated in Japan. Finally, Bayesian clustering and chloroplast haplotype analysis showed that the 116 Chinese chestnut cultivars could be divided into two groups: one originated in the Hebei region of China and the other originated in the Jiangsu and Anhui regions of China. The Chinese chestnut cultivars selected in Japan showed various patterns of genetic structure including Hebei origin, Jiangsu or Anhui origin, and admixed. The chestnut cultivar genetic classifications obtained in this study will be useful for both Japanese and Chinese chestnut breeding programs.

Highlights

Japanese chestnut (Castanea crenata Sieb. et Zucc.) and Chinese chestnut (C. mollissima Bl.) are naturally distributed throughout Japan and China, respectively
The Chinese chestnut cultivars selected in Japan showed various patterns of genetic structure including Hebei origin, Jiangsu or Anhui origin, and admixed
These include Japanese chestnut local cultivars that originated in the Kanto region of Japan, the Tanba region of Japan (J_TA), other regions of Japan (J_OJ), and Korea (KOR); Japanese–Chinese chestnut hybrids developed in Japan (HYB); and Chinese chestnut cultivars selected in Japan (C_SJ) and introduced from other countries (C_IO)

Summary

Introduction

Japanese chestnut (Castanea crenata Sieb. et Zucc.) and Chinese chestnut (C. mollissima Bl.) are naturally distributed throughout Japan and China, respectively. Et Zucc.) and Chinese chestnut (C. mollissima Bl.) are naturally distributed throughout Japan and China, respectively. Both species are reported to have been prehistorically domesticated [1,2,3] and are still economically important for production of edible nuts. These two species have large differences in both genetic and morphological properties. In Japan, Chinese chestnut has been applied in Japanese chestnut breeding programs to improve nut quality and pellicle peelability [10,11]. It is important to clarify the genetic relationships among chestnut cultivars of different species

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