AUTHOR=Huang Xin , Qin Bo , Qin Lei , Peng Zhihong , Xia Shitou , Su Yi , Sun Kaidao , Peng Keqin 

TITLE=A comparative study on photosynthetic characteristics and flavonoid metabolism between Camellia petelotii (Merr.) Sealy and Camellia impressinervis Chang &Liang

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1071458

DOI=10.3389/fpls.2022.1071458

ISSN=1664-462X

ABSTRACT=<p><italic>Camellia petelotii</italic> (Merr.) Sealy and <italic>Camellia impressinervis</italic> Chang &amp; Liang belong to the golden subgroup of <italic>Camellia</italic> (Theaceae). This subgroup contains the yellow-flowering species of the genus, which have high medicinal and ornamental value and a narrow geographical distribution. These species differ in their tolerance to high light intensity. This study aimed to explore the differences in their light-stress responses and light damage repair processes, and the effect of these networks on secondary metabolite synthesis. Two-year-old plants of both species grown at 300 µmol·m<sup>-2</sup>·s<sup>-1</sup> photosynthetically active radiation (PAR) were shifted to 700 µmol·m<sup>-2</sup>·s<sup>-1</sup> PAR for 5 days shifting back to 300 µmol·m<sup>-2</sup>·s<sup>-1</sup> PAR for recovery for 5 days. Leaf samples were collected at the start of the experiment and 2 days after each shift. Data analysis included measuring photosynthetic indicators, differential transcriptome expression, and quantifying plant hormones, pigments, and flavonoids. <italic>Camellia impressinervis</italic> showed a weak ability to recover from photodamage that occurred at 700 µmol·m<sup>-2</sup>·s<sup>-1</sup> compared with <italic>C. petelotii.</italic> Photodamage led to decreased photosynthesis, as shown by repressed transcript abundance for photosystem II genes <italic>psbA, B, C, O,</italic> and <italic>Q</italic>, photosystem I genes <italic>psaB, D, E, H,</italic> and <italic>N</italic>, electron transfer genes <italic>petE</italic> and <italic>F</italic>, and ATP synthesis genes <italic>ATPF1A</italic> and <italic>ATPF1B</italic>. High-light stress caused more severe damage to <italic>C. impressinervis</italic>, which showed a stronger response to reactive oxygen species than <italic>C. petelotii.</italic> In addition, high-light stress promoted the growth and development of high zeatin signalling and increased transcript abundance of adenylate dimethylallyl transferase (IPT) and histidine-containing phosphotransferase (AHP). The identification of transcriptional differences in the regulatory networks that respond to high-light stress and activate recovery of light damage in these two rare species adds to the resources available to conserve them and improve their value through molecular breeding. </p>