*4.1. Plant Materials*

Avocado fruits (cultivar 'Hass') were harvested from six 10-year-old trees grafted onto Zutano clonal rootstock (two trees were used as a unit for each biological replicate) from April 2018 to September 2018 at the Chinese Academy of Tropical Agricultural Sciences (Danzhou, Hainan, China: 19.52◦N, 109.57◦E; altitude = 200 m above sea level). In these trees, fruits that developed during the main flowering season (i.e., February 2018) were marked, after which samples were collected at five time-points (75, 110, 145, 180, and 215 DAFB) until the fruits reached physiological maturity (defined as the ability to ripen after harvest). Two sets of fruits were randomly collected for each biological replicate during each developmental stage. The first set of nine fruits was used to measure fruit, mesocarp, and seed phenotypic traits. The second set of nine fruits was used for transcript and carotenoid analyses. Fruits were quickly brought to the laboratory, after which their phenotypic traits were measured as previously described [7] or they were immediately frozen at −80 ◦C for transcript and carotenoid analyses.
