Light energy management in micropropagated plants of Castanea sativa, effects of photoinhibition.
The limited development of photoprotective mechanisms, specifically heat dissipation capacity, found in micropropagated plants may be the result of low xanthophyll cycle pigment content and reduced de-epoxidation capacity making them highly susceptible to photodamage. The effects of gradual or sudden increase of light on Castanea sativa in vitro cultured and during their ex vitro transference was evaluated. The results were compared with those determined in nursery-grown plants. In vitro plants responded poorly to gradual increase in irradiance, exhibiting a low electron transport rate (ETR) agreeing with low non-photochemical quenching (NPQ) and a limited de-epoxidation capacity, not synthesizing detectable amounts of zeaxanthin (Z). Regarding a sudden increase in light (photoinhibition treatment, PhT); post-PhT as in vitro as well nursery plants showed a significant decrease in their maximal efficiency of PSII (F(v)/F(m)), but in vitro the decrease was very drastic (around 0.2) different from that observed in nursery (around 0.69). In vitro, NPQ was mainly determined by the slow relaxing component, NPQ(s) (80.8%), concomitant with a pronounced decrease of D1 protein post-PhT, and a lack of de-epoxidation capacity. During ex vitro transfer, PhT lead to death of some plants, specifically during root induction. The photoprotective mechanisms were activated over time in ex vitro conditions, indicating that micropropagated Castanea sativa display a potential for light acclimation, adjusting their photosynthetic apparatus to the ambient growth irradiance. Understanding the mechanisms that micropropagated plants deployed and how they face high light intensity events, will allow us to search for strategies to improve performance to possible light fluctuations that normally occur in ex vitro conditions during plant acclimation.
Laboratorio Cultivo de Tejidos Vegetales, Facultad de Ciencias Forestales y Centro de Biotecnología, Universidad de Concepción, Casilla 160-C, Concepción, Chile. patrisaezd@gmail.com
Patricia L
PL
Sáez
León A
LA
Bravo
Mirtha I
MI
Latsague
Marcelo J
MJ
Toneatti
Manuel
M
Sánchez-Olate
Darcy G
DG
Ríos
D000064:Acclimatization; D002734:Chlorophyll / Q000032:analysis; D060365:Chloroplast Proteins / Q000032:analysis / Q000737:chemistry; D004579:Electron Transport; D004734:Energy Metabolism; D029962:Fagaceae / Q000737:chemistry / Q000254:growth & development / Q000528:radiation effects*; D008027:Light; D010084:Oxidation-Reduction; D055668:Photochemical Processes / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry / Q000254:growth & development / Q000528:radiation effects; D018517:Plant Roots / Q000737:chemistry / Q000254:growth & development; D020524:Thylakoids / Q000737:chemistry; D024341:Xanthophylls / Q000737:chemistry; D065146:Zeaxanthins; D019207:beta Carotene / Q000032:analysis / Q000737:chemistry
D060365:Chloroplast Proteins; D045332:Photosystem II Protein Complex; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D002734:Chlorophyll