Identification of a natural hybrid between Castanopsis sclerophylla and Castanopsis tibetana (fagaceae) based on chloroplast and nuclear dna sequences

Abstract

Castanopsis × kuchugouzhuiHuang et Y. T. Chang was recorded in Flora Reipublicae Popularis Sinicae (FRPS) as a hybrid species on Yuelushanmountain, but it is treated as a hybrid between Castanopsis sclerophylla (Lindl.) Schott. and Castanopsis tibetana Hance in Flora of China. After a thorough investigation on Yuelushan mountain, we found a population of C. sclerophylla and one individual of C. × kuchugouzhui, but no living individual of C. tibetana. We collected C. × kuchugouzhui, and we sampled 42 individuals of C. sclerophylla fromYuelushan and Xiushui and 43 individuals of C. tibetana fromLiangyeshan and Xiushui. WeusedchloroplastDNAsequences and29nuclearmicrosatellitemarkers to investigate ifC. xkuchugouzhui is a natural hybrid between C. sclerophylla and C. tibetana. The chloroplast haplotype analysis showed that C. × kuchugouzhuishared haplotype H2 with C. sclerophylla on Yuelushan. The STRUCTURE analysis identified two distinct genetic pools that corresponded well to C. sclerophylla and C. tibetana, revealing the genetic admixture of C. × kuchugouzhui. Furthermore, the NewHybrids analysis suggested that C. × kuchugouzhuiis an F2 hybrid between C. sclerophylla and C. tibetana. Our results confirm that C. × kuchugouzhuirecorded in FRPS is a rare hybrid between C. sclerophylla and C. tibetana.