Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (3): 361-373.DOI: 10.17521/cjpe.2021.0446

Special Issue: 青藏高原植物生态学:生理生态学 光合作用

• Research Articles • Previous Articles     Next Articles

Responses of photosynthetic function of Kobresia pygmaea to simulated nocturnal low temperature on the Qingzang Plateau

SHI Sheng-Bo1,3,*(), ZHOU Dang-Wei1, LI Tian-Cai1, DE Ke-Jia2, GAO Xiu-Zhen1, MA Jia-Lin1, SUN Tao3, WANG Fang-Lin3   

  1. 1Key Laboratory of Adaptation and Evolution of Plateau Biology, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
    2Qinghai Academy of Animal Science and Veterinary Medicine, Qinghai University, Xining 810016, China
    3State Key Laboratory Breeding Base of Desertification and Aeolian Sand Disaster Combating, Gansu Desert Control Research Institute, Lanzhou 730070, China
  • Received:2021-12-02 Accepted:2022-05-21 Online:2023-03-20 Published:2022-10-11
  • Contact: SHI Sheng-Bo
  • Supported by:
    Qinghai Province Naturnal Science Foundation(2019-ZJ-7016);Construction Project for Innovation Platform of Qinghai Province(2017-ZJ-Y20);Construction Project for Innovation Platform of Qinghai Province(2021-ZJ-Y05);National Natural Science Foundation of China(31660237)


Aims Kobresia pygmaea is a perennial cushion herb from the Cyperaceae family with a height of 1-3 cm and small linear leaves about 1 mm wide. It is mainly distributed on the low slopes of the high mountains ranging from 3 000 m to 5 960 m on the Qingzang Plateau. Its habitat is harsh, and extreme climate conditions such as low temperature, strong wind, and high sunlight intensity are the main abiotic stresses during plants growing season. The objectives of this study were to analyze the photochemical and non-photochemical energy distribution of the photosystem II (PSII) reaction center in K. pygmaea leaves, and their quenching protection mechanism after nocturnal low-temperature (NLT) treatment.

Methods Kobresia pygmaea meadow turfs (30 cm × 15 cm) were collected from the Alpine Grassland Ecosystem Research Station of the Resource of Three Rivers. The turf blocks were separated into two groups, one group was kept in a culture room with a temperature of 24/18 °C (day/night) as a control treatment, and another was kept in an artificial climate chamber with 0 °C in the evening as an NLT treatment. During the daytime, the NLT group was moved back to the culture room and irradiated together with the control group. On day 0, day 1, day 3, and day 5 after NLT treatment, the chlorophyll fluorescence of K. pygmaea leaves including, the light-response curve, PSII photochemical efficiency at 400 and 1 500 μmol·m−2·s−1 steady-state light intensities, and dark relaxation were monitored using CF imager. Then, based on the “Lake Model”, the variation of the PSII actual photochemical efficiency (ΦPSII), the quantum yield of non-regulated energy dissipation (ΦNO) and regulated energy dissipation (ΦNPQ) were explored. Additionally, the fast and slow relaxation components of PSII non-photochemical quenching were determined.

Important findings Nocturnal low temperature had limited effects on the rapid light-response curves of PSII relative electron transfer rate through PSII (rETR), the fraction of open PSII centers (qL), and PSII non-photochemical quenching coefficient (qNP). The comparison of chlorophyll fluorescence between 400 and 1 500 μmol·m−2·s−1 steady-state light intensities confirmed that NLT treatment did not affect the activity of the PSII reaction center and the process of non-photochemical quenching of K. pygmaea. On the third day after NLT treatment, under high light intensity, the ratios of ΦPSII:ΦNO:ΦNPQ were 36:19:45 and 38:19:43 in the control and NLT groups, respectively; while under lower light intensity, they were 66:22:12 and 66:23:11, respectively. The fast relaxation component (NPQf) was the main component in non-photochemical quenching (NPQ); the proportion of the slow relaxation component in non-photochemical quenching was 11% and 10% on day 1 and day 3 in control group, and 13% and 12% in NLT group, respectively. Our results indicated that the probability of photoinhibition of the PSII reaction center in K. pygmaeawas increased after NLT treatment; low light intensity and NLT led to the prolongation of photosynthetic induction time. Overall, the NLT treatment did not increase the tendency of excess excitation energy to be difficult to regulate and dissipate in K. pygmaea leaves, since PSII photochemical energy dissipation and protective regulation mechanism still effectively distributed the absorbed light energy.

Key words: nocturnal low temperature, photosystem II non-photochemical quenching, Kobresia pygmaea, Qingzang Plateau, chlorophyll fluorescence