Genotype-dependent Strategies to "Overcome" Excessive Light: Insights into Non-Photochemical Quenching under High...

High light (HL) intensities have a significant impact on energy flux and distribution within photosynthetic apparatus. To understand the effect of high light intensity (HL) on the HL tolerance mechanisms in tomatoes, we examined the response of the photosynthesis apparatus of 12 tomato genotypes to HL. A reduced electron transfer per reaction center (ET₀ /RC), an increased energy dissipation (DI₀ /RC) and non-photochemical quenching (NPQ), along with a reduced maximum quantum yield of photosystem II (F_V /F_M ), and performance index per absorbed photon (PI_ABS ) were common HL-induced responses among genotypes; however, the magnitude of those responses was highly genotype-dependent. Tolerant and sensitive genotypes were distinguished based on chlorophyll fluorescence and energy-quenching responses to HL. Tolerant genotypes alleviated excess light through energy-dependent quenching (q_E ), resulting in smaller photoinhibitory quenching (q_I ) compared to sensitive genotypes. Quantum yield components also shifted under HL, favoring the quantum yield of NPQ (Փ_NPQ ) and the quantum yield of basal energy loss (Փ_N0 ), while reducing the efficient quantum yield of PSII (Փ_PSII ). The impact of HL on tolerant genotypes was less pronounced. While the energy partitioning ratio did not differ significantly between sensitive and tolerant genotypes, the ratio of NPQ components, especially q_I , affected plant resilience against HL. These findings provide insights into different patterns of HL-induced NPQ components in tolerant and sensitive genotypes, aiding the development of resilient crops for heterogeneous light conditions.