The desert green algae Chlorella ohadii thrives at excessively high light intensities by exceptionally enhancing the mechanisms that protect photosynthesis from photoinhibition

Abstract

SUMMARY Although light is the driving force of photosynthesis, excessive light can be harmful. One of the main processes that limits photosynthesis is photoinhibition, the process of light‐induced photodamage. When the absorbed light exceeds the amount that is dissipated by photosynthetic electron flow and other processes, damaging radicals are formed that mostly inactivate photosystem II (PSII). Damaged PSII must be replaced by a newly repaired complex in order to preserve full photosynthetic activity. Chlorella ohadii is a green microalga, isolated from biological desert soil crusts, that thrives under extreme high light and is highly resistant to photoinhibition. Therefore, C. ohadii is an ideal model for studying the molecular mechanisms underlying protection against photoinhibition. Comparison of the thylakoids of C. ohadii cells that were grown under low light versus extreme high light intensities found that the alga employs all three known photoinhibition protection mechanisms: (i) massive reduction of the PSII antenna size; (ii) accumulation of protective carotenoids; and (iii) very rapid repair of photodamaged reaction center proteins. This work elucidated the molecular mechanisms of photoinhibition resistance in one of the most light‐tolerant photosynthetic organisms, and shows how photoinhibition protection mechanisms evolved to marginal conditions, enabling photosynthesis‐dependent life in severe habitats.

Supra-Optimal Temperature: An Efficient Approach for Overaccumulation of Starch in the Green Alga Parachlorella kessleri

“…Altogether, this documents the plasticity of the multiple fission lifestyle, which allows the cells to slightly prolong the growth phase in order to be able to reach a critical cell size for starting another reproductive sequence, and to maintain the reproduction potential at the expense of producing slightly smaller daughter cells with altered cell compositions. Such growth and metabolic plasticity of algae allows them to thrive both at low light intensities [ 68 , 69 ], and in the harsh conditions of a desert, with very high light intensity and extreme fluctuating temperatures [ 73 , 74 , 75 , 76 ].…”

Harnessing photosynthesis to produce electricity using cyanobacteria, green algae, seaweeds and plants

“…Other potentially valuable organisms for microalgae based BPEC are Chlorella ohadii and Chlorella sorokiniana . Chlorella ohadii was isolated from the sand crust of the Israeli desert and characterized as the most rapidly growing photosynthetic eukaryote that is resistant to extreme high light intensities in which other microalgae and plants are photobleached ( Levin et al, 2021 ).…”

Photoprotection conferring plant tolerance to freezing stress through rescuing photosystem in evergreen Rhododendron

“…ELIPs in higher plants are nuclear‐encoded and located in thylakoid membranes (Heddad et al, 2006). They are generally recognized to exhibit photoprotective properties under high light stress and low temperatures through binding with chlorophyll a and xanthophylls (lutein and zeaxanthin) (Adamska & Kloppstech, 1994; Adamska et al, 1999; Havaux & Kloppstech, 2001; Heddad et al, 2006; Levin et al, 2021; Tzvetkova‐Chevollear et al, 2007). In Arabidopsis, AtELIP1 and AtELIP2 were proved to be mediated by the blue light photoreceptor, cryptochrome1 (CRY1), and/or transcription factor (TF) elongated hypocoty 5 (HY5) when responding to the high irradiance (Hayami et al, 2015; Kleine et al, 2007).…”