Distinct Morphological, Physiological, and Biochemical Responses to Light Quality in Barley Leaves and Roots

Abstract

Light quality modulates plant growth, development, physiology, and metabolism through a series of photoreceptors perceiving light signal and related signaling pathways. Although the partial mechanisms of the responses to light quality are well understood, how plants orchestrate these impacts on the levels of above- and below-ground tissues and molecular, physiological, and morphological processes remains unclear. However, the re-allocation of plant resources can substantially adjust plant tolerance to stress conditions such as reduced water availability. In this study, we investigated in two spring barley genotypes the effect of ultraviolet-A (UV-A), blue, red, and far-red light on morphological, physiological, and metabolic responses in leaves and roots. The plants were grown in growth units where the root system develops on black filter paper, placed in growth chambers. While the growth of above-ground biomass and photosynthetic performance were enhanced mainly by the combined action of red, blue, far-red, and UV-A light, the root growth was stimulated particularly by supplementary far-red light to red light. Exposure of plants to the full light spectrum also stimulates the accumulation of numerous compounds related to stress tolerance such as proline, secondary metabolites with antioxidative functions or jasmonic acid. On the other hand, full light spectrum reduces the accumulation of abscisic acid, which is closely associated with stress responses. Addition of blue light induced accumulation of γ-aminobutyric acid (GABA), sorgolactone, or several secondary metabolites. Because these compounds play important roles as osmolytes, antioxidants, UV screening compounds, or growth regulators, the importance of light quality in stress tolerance is unequivocal.

The role of far-red light (FR) in photomorphogenesis and its use in greenhouse plant production

“…It was shown that the R: FR ratio affects different steps of plant nutrition that are critical for enhanced and sustainable crop production. It can affect root structure (De Simone et al, 2000;Gundel et al, 2014) or root growth (Klem et al, 2019). The establishment of a nitrogen-fixing symbiosis between legumes and rhizobia requires not only sufficient primary metabolites but also the sensing of the R : FR ratio (Suzuki et al, 2011).…”

Photosynthetic potential of spring barley in the conditions of the Lower Volga region

“…Показатели площади листьев, продолжительность их работы и накопление сухой биомассы определяют продуктивность фотосинтетической деятельности посевов. Площадь листьев является одним из важных показателей, характеризующих фотосинтетическую деятельность растений, и урожай тесно связан именно с размерами площади листьев [14,16,17].…”

Comparative physiological and transcriptomic analysis of pear leaves under distinct training systems

“…Fluctuating light is ubiquitous within canopy, and all leaves are shaded to some degree during their lifecycle. Shaded light is characterized by low light intensity (decreased PAR), a low red/far-red light ratio and low blue light 23 – 25 . PAR is a primary driving force for photosynthesis, and different wavelengths of light are considered to be important environmental signals 25 – 27 .…”

“…Shaded light is characterized by low light intensity (decreased PAR), a low red/far-red light ratio and low blue light 23 – 25 . PAR is a primary driving force for photosynthesis, and different wavelengths of light are considered to be important environmental signals 25 – 27 . Circadian clock is an internal timing mechanism that allows plants as sessile organisms to synchronize with environmental cues 28 .…”