Changes in photosynthesis and carotenoid composition of pepper (Capsicum annuum L.) in response to low-light stress and low temperature combined with low-light stress

Abstract

Light and temperature are two major factors for plant growth. Carotenoids are important photoprotective and lightharvesting pigments in photosynthetic organs. Therefore, this study explored photosynthesis and carotenoid-related metabolism under control (CK), low-light (L), and low-temperature and low-light (LL) conditions by using the pepper (Capsicum annuum L.) varieties Longjiao 5 and Hangjiao 4. We found the increased inhibition of plant growth and photosynthetic capacity under both L and LL stress. Meanwhile, carotenoid-related metabolic compounds accumulated in pepper showed different responses to the two stresses. Significantly, zeaxanthin contents were 6.69-8.88 times higher under LL than that of CK, α-carotene contents were 0.9-2.1 times higher under L than that of CK, which may enhance the tolerance to LL and L. Our findings provide a foundation for further research on the molecular mechanism of carotenoid functions regarding L and LL tolerance by regulating photosynthesis.

Transcriptome sequence and physiological analysis revealed the roles of carotenoids and photosynthesis under low temperature combined with low-light stress on pepper (Capsicum annuum L.)

“…Lhc are membrane intrinsic proteins: Lhca and Lhcb groups, which serve as photosystem I and photosystem II antenna, respectively, and noncovalently bind to Chl a, Chl b, and carotenoids (lutein, neoxanthin, violaxanthin, and zeaxanthin) (Kirilovsky andBüchel 2019, Song et al 2020). LL stress decreases photosynthesis (Zhang et al 2020a) and causes photosynthetic organisms damage by excessive energy. Lhc family members are involved in the nonphotochemical quenching that accelerates heat dissipation depending on a pH gradient in the thylakoid membrane and xanthophyll de-epoxidation (Kirilovsky and Büchel 2019).…”

“…The chilling injury index was calculated according to Zhang et al (2020a) after 20 d in darkness under 4°C. The CI was calculated according to the equation:…”

“…The chlorophyll (Chl) a, Chl b, Chl (a+b), and total carotenoid (Car) were determined after treatment for 15 d according to (Zhang et al 2020a) using 80% acetone.…”

“…Our previous studies found that LL causes changes in carotenoid-related compounds in response to LL (Zhang et al 2020a), but the mechanism is unknown. Moreover, little information focused on transcriptome analysis of pepper (Capsicum annuum L.) in response to LL stress is reported till now.…”

Exogenous Zeaxanthin Alleviates Low Temperature Combined with Low Light Induced Photosynthesis Inhibition and Oxidative Stress in Pepper (Capsicum annuum L.) Plants

“…Zeaxanthin (Z) is a carotenoid found mainly in thylakoids—also in the chloroplast envelope—where it is involved in photoprotection via a role in thermal energy dissipation and antioxidation [ 24 ]. Z content in peppers, when increased under low temperatures and low light, showed improved stress tolerance [ 25 ]. As an antioxidant in plants, Z acts as a lipid protectant and ROS scavenger [ 26 ]; Z directly quenches ROS [ 27 ] and triggers non-photochemical quenching of triplet chlorophyll and singlet oxygen—thereby playing a protective role in the photosynthetic system of plant cells [ 28 , 29 ].…”