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

Abstract

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

Protein Changes in Shade and Sun Haberlea rhodopensis Leaves during Dehydration at Optimal and Low Temperatures

“…Moreover, apiose/xylose can also be linked to glucose residues of phenolic/phenylpropanoid glycosides in Gesneriaceae in a taxon-specific way [ 58 , 59 ]. In Camellia species, the enhanced UDP-D-apiose content was found to correlate with cold stress resistance [ 60 ]. The importance of the accumulation of phenolics is further supported by the detection/increased accumulation of the 55 kDa hypothetical protein/81E8-like cytochrome P450 monooxygenase in desiccated samples.…”

Temperature‐smart plants: A new horizon with omics‐driven plant breeding

“…For instance, when crop development reaches the anther differentiation stage, CS can lead to production losses of up to 30–50% (Liu et al, 2019; Hassan et al, 2021). Recent data revealed that CS adversely impacts critical crop growth stages in cereals, resulting in carbohydrate accumulation that alters hormone contents (Xu et al, 2022a). Furthermore, CS significantly affects proteins involved in carbohydrate metabolism, protein folding, dilapidation, and stress, and the synthesis of compatible solutes (Raza et al, 2021b; Mehmood et al, 2021; Raza et al, 2021c; He et al, 2023; Seydel et al, 2022).…”

Comprehensive applications of metabolomics on tea science and technology: Opportunities, hurdles, and perspectives

“…Many studies have revealed significant changes of primary and secondary metabolites under cold stress, mainly including carbohydrates, organic acids, amino acids, and flavonoids. For instance, the contents of sugars ( e.g ., glucose) and several key metabolites associated with sugar metabolism, including UDP‐glucose, UDP‐apiose, and fructose/glucose‐6‐phosphate constantly elevated during cold acclimation but decreased in levels during deacclimation (Shen et al., 2019; Xu, Huang et al., 2022; Yue et al., 2015). Amino acids, mainly including proline, valine, glycine, glutamine, serine, and tryptophan were highly accumulated in cold‐resistant tea cultivars, while the organic acids accumulated in large quantities were mainly those involved in the tricarboxylic acid (TCA) cycle, such as fumaric acid and α ‐ketoglutarate (Wang, Di et al., 2022).…”