Photoperiod-dependent photosynthetic apparatus organization and efficiency in seedlings of common bean (Phaseolus vulgaris L.) cultivars from Andean and Mesoamerican gene pools

Common bean ( Phaseolus vulgaris L.) cultivars from Andean and Mesoamerican gene pools exhibit distinct genomic characteristics, yet their photosynthetic apparatus organization remains poorly characterized. We investigated photochemical efficiency and chlorophyll-protein (CP) complex organization in four cultivars: Cranberry and Dark Red Kidney (Andean origin) versus Calypso and Black Turtle (Mesoamerican origin) grown under long-day (16 h) and short-day (8 h) conditions. Using pulse-amplitude-modulated fluorescence, low-temperature fluorescence spectroscopy, circular dichroism, and Blue Native PAGE, we assessed photosystems' performance and CP complex organization. Contrary to expectations based on ecogeographic origin, photosynthetic characteristics of studied cultivars did not correlate with gene pool classification. All four cultivars showed reduced photosynthetic efficiency under short-day conditions, with no clear separation between Andean- and Mesoamerican-origin plants. Black Turtle exhibited markedly different behavior from other cultivars, displaying superior PSII efficiency but reduced PSI performance under short-day conditions, along with unique CP complex organization characterized by distinct fluorescence emission patterns and altered supercomplex assembly. Surprisingly, Mesoamerican Calypso responded similarly to both Andean cultivars. These findings indicate that, within the four cultivars examined, photosynthetic apparatus organization and efficiency did not cluster by gene pool of origin. Our results indicate that cultivar-level photosynthetic profiling may provide information that is not captured by ecogeographic classification alone.