title: Differential characteristics of photochemical acclimation to cold in two contrasting sweet sorghum hybrids.
abstract: Sweet sorghum has a photosynthetic system which is highly sensitive to cold stress and hence strongly limits its development in temperate environments; therefore, the identification of key exploitable cold tolerance traits is imperative. From a preliminary field trial, two dissimilar sweet sorghum hybrids (ICSSH31 and Bulldozer), in terms of early vigor and productivity, were selected for a controlled-environment trial aiming at identifying useful traits related to acclimation mechanisms to cold stress. The higher cold tolerance of Bulldozer was partially related to a more efficient photochemical regulation mechanism of the incoming light energy: the higher tolerance of photosystem II (PSII) to photo-inactivation was because of a more effective dissipation capacity of the excess of energy and to a more balanced diversion of the absorbed energy into alternative energy sinks. ICSSH31 increased the dissipation and accumulation of a large amount of xanthophylls, as in Bulldozer, but, at the same time, inactivated the oxygen evolving complex and the re-synthesis of chlorophyll (Chl) a and b, thus, leading to an overproduction of CO2 fixation enzymes after re-warming. In summary, in Bulldozer, the acclimation adjustments of the photosynthetic apparatus occurred through an efficient control of energy transfer toward the reaction centers, and this likely allowed a more successful seedling establishment; ICSSH31, conversely, exhibited a fast re-synthesis of Chl pigments, which appears to divert photosynthates from dry matter accumulation. Such broad acclimation traits may constitute a source for selecting higher genetic gain traits relevant for enlarging the growing season of promising biomass sorghum ideotypes in temperate climates.
authors: Department of Agricultural Sciences, University of Bologna, Viale G. Fanin 44, 40126, Bologna, Italy.
authors: Walter
authors: W
authors: Zegada-Lizarazu
authors: Instituto de Fisiología y Recursos Genéticos Vegetales, Centro de Investigaciones Agropecuarias (IFRGV-CIAP, formerly IFFIVE), INTA (Instituto Nacional de Tecnología Agropecuaria), Camino a 60 Cuadras, Km 5.5, X5020ICA Córdoba, Argentina.
authors: Dario
authors: D
authors: Fernando Luna
authors: Department of Agricultural Sciences, University of Bologna, Viale G. Fanin 44, 40126, Bologna, Italy.
authors: Andrea
authors: A
authors: Monti
mesh_terms: D000064:Acclimatization; D002734:Chlorophyll / Q000378:metabolism; D003080:Cold Temperature; D008027:Light; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D036226:Seedlings / Q000502:physiology* / Q000528:radiation effects; D045868:Sorghum / Q000502:physiology* / Q000528:radiation effects; D013312:Stress, Physiological; D024341:Xanthophylls / Q000378:metabolism
chemical_list: D045332:Photosystem II Protein Complex; D024341:Xanthophylls; D002734:Chlorophyll