1.1 Sampling
The leaves of Alsophila denticulata Baker and Alsophila metteniana Hance were collected from Nankunshan in Huizhou and the botanical garden of South China Agricultural University in Guangzhou, respectively. The leaves ofAlsophila podophylla Hook and Alsophila gigantean Wall. ex Hook were collected from the South China Botanical Garden of the Chinese Academy of Sciences in Guangzhou (Liu et al., 2018; Wang et al., 2019b). The leaves ofAlsophila costularis Baker, Sphaeropteris brunoniana(Hook.) R. M. Tryon, and Sphaeropteris lepifera (Hook.) R. M. Tryon were collected from the Fairy Lake Botanical Garden of the Chinese Academy of Sciences in Shenzhen(Wang et al., 2019a; Liu et al., 2020; Zhu et al., 2020). The leaves of Alsophila spinulosa (Wall. ex Hook.) R. M. Tryon were collected from the Wuhan Botanical Garden of the Chinese Academy of Sciences in Wuhan (Gao et al., 2009). Fresh young leaves from well-grown plants were collected, wrapped in tin paper, flash-frozen in liquid nitrogen, and then stored at -80 °C before use.