Impact of Cold Stress on Leaf Structure, Photosynthesis, and Metabolites in Camellia weiningensis and C. oleifera Seedlings

Camellia weiningensis Y. K. Li. sp. nov. (CW) is an endemic oil-tea species in Guizhou province, distributed the alpine karst area, which exhibits cold resistance and better economic characters than C. oleifera (CO). The mechanism of response CW seedlings has not been studied depth. Herein, we performed anatomical, physiological, metabolic analyses to assess impact stress on leaf structure, photosynthesis, metabolites CO seedlings. Anatomical analysis leaves showed had greater palisade thicknesses, tissue structure tightness, palisade-spongy ratio enhance chilling (4 °C) tolerance, but freezing (?4 caused loosening both Photosynthetic a reduction chlorophyll (Chl) fluorescence (Fv/Fm) photosynthetic parameters under Cold increased abscisic acid (ABA) contents species, exhibited highest ABA content ?4 °C treatment. Additionally, indole-3-acetic (IAA) was also stress. An obviously distinct metabolite composition observed for different temperatures, significantly changed (SCMs) were enriched Prenol lipids, organooxygen compounds, fatty acyls main two top key SCMs, such as medicoside G, cynarasaponin F, yuccoside C, methionyl-proline downregulated CO. some associated with sugar metabolism, UDP-glucose, UDP-D-apiose, fructose 6-phosphate, higher CO, may contribute enhancing CW. Our findings are helpful explaining how adapt environments, will provide reference tolerance improvement application stress-resistant breeding areas.