Autopolyploidy enhances agronomic traits and active ingredients in ‘Huaibai’, a top-grade medicinal chrysanthemum

Chrysanthemum morifolium cv. ‘Huaibai’ is a well-known medicinal chrysanthemum. However, ‘Huaibai’ plants are susceptible to severe diseases due to long-term asexual reproduction, moreover, slender stems make ‘Huaibai’ prone to lodging, which can seriously affect the yield and medicinal quality. In this study, autodecaploid plants were induced from pentaploid ‘Huaibai’ (2n = 5 x = 45) by 0.05% colchicine treatment for 9 h and checked by flow cytometry and chromosome counting. Compared with their pentaploid counterparts, autodecaploids showed superior agronomic characteristics, including shorter plant height, thicker stem and root, darker green leaf, larger flower, bigger stoma, and more chloroplasts per guard cell. Furthermore, significant improvements on yield and disease resistance were both observed in the autodecaploids. Additionally, the content of chlorogenic acid (CA), luteoloside (LO) and 3,5-O-dicaffeoylquinic acid (DCQA), which are desired active ingredients of medicinal chrysanthemum, was higher in autodecaploids compared with pentaploids. In short, autodecaploids not only possess excellent agronomic traits and increased yield, but also have enhanced disease resistance and improved medicinal quality. Thus, chromosome doubling could be employed effectively as a strategy to acquire novel ‘Huaibai’ varieties with high yield and premium quality that are more suitable for market requirements.