Negev desert alga Chlorella ohadii combines fast growth with tolerance of extreme heat and light

Haim Treves, a professor of plant metabolism at RPTU, has studied the alga since its discovery ^[2]. He explained why the desert was the place to look. "Looking at the Negev Desert, one of the harshest environments on Earth, we assumed that anything that survives there could help us better understand the potential and limitations of photosynthesis and develop more resilient crops for the future," Treves said ^[4]. The New Phytologist paper, first-authored by Or Geffen, presents the alga as "an emerging model" ^[3]. RPTU says it has become a key organism in photosynthesis research within a few years ^[1].

The group's headline finding is about a trade-off. According to RPTU, scientists had assumed an organism could be particularly resilient or grow well under optimal conditions, but not both, and Chlorella ohadii refutes that ^[12]. The alga resists extremely intense light, dehydration and high temperatures ^[7], and it still grows fast. One species doing both is enough to show the trade-off is not universal.

Treves ties the speed to a short growing window. "In the desert, the green alga has less than an hour each morning to grow. It must react quickly and flexibly to changing conditions. It achieves this because the light-driven redox reactions proceed at lightning speed," he said ^[13]. That account draws on physiological, biochemical and molecular work, including genomic, protein and metabolic analyses ^[8]. Fast redox chemistry explains how the cell fits its growth into a morning. Finding speed and hardiness in the same species does not establish that one produces the other. Nor does it show that a plant engineered for speed would inherit the hardiness.

The crop claim rests on one quotation. "We're currently in the process of patenting a metabolically modified plant that exhibits traits similar to those of the desert alga and whose seed yield has been increased by 30%. This is how we're harnessing the potential of this tiny alga to help secure our food supply," Treves said ^[15]. The group tests the alga's genes, structures and traits in both model and crop plants, with the aim of raising yields ^[14]. The account does not name the patented plant's species, how it was grown, or the line it was compared against.

Those details decide what the 30% means. Measured under ideal watering, the gain would be a yield result. Measured under heat or drought, the same gain would test the trade-off inside a plant.