engleski

Photochemistry of thylakoid membranes in two pea cultivars with different leaf colouration

Photochemical features of thylakoid membranes and chlorophyll content were investigated in two pea (Pisum sativum L.) cultivars with different leaf colouration: ‘Assas’ (red leaves) and ‘Arvika’ (green leaves). In vivo measured chlorophyll fluorescence (OJIP) was used to evaluate overall photosynthetic efficiency (expressed as performance index, PIABS) as well as for advanced analysis of main photochemical processes per active reaction centre (RC) of photosystem II (PSII). To evaluate the response of PSII driven linear electron transport (relETR) and non- photochemical quenching (NPQ), investigated plants were challenged with short-term high light (~2000 µmol m-2s-1). In spite of prevailing red colour, leaves of cv. ‘Assas’ had identical levels of chlorophylls a and b as green ones. The OJIP transients showed that red leaves grown in field (500–800 µmol m-2s-1) had decreased PIABS and electron transport per RC beyond primary acceptor (QA-) compared to green leaves. After high light exposure red leaves revealed impaired relETR accompanied with increased NPQ values. Anthocyanins located in epidermal cells affect neither chlorophylls levels nor the light capture features of PSII. Despite equal levels of chlorophylls and PSII photochemistry further than QA- in both leaf types, red leaves reduced overall photosynthetic efficiency due to impaired relETR in thylakoid membranes.

Pisum sativum L. ; Anthocyanins ; Chlorophyll fluorescence ; Photosynthesis ; Photoprotection

nije evidentirano