Responses of antioxidant enzymes, photosynthetic pigments and carbohydrates in micropropagated Pitcairnia encholirioides L.B. Sm. (Bromeliaceae) under ex vitro water deficit and after rehydration

Abstract In this study, the activities of antioxidant enzymes, photosynthetic pigments, proline and carbohydrate contents in Pitcairnia encholirioides under ex vitro conditions of water deficit were evaluated. Results show that plants under progressive water stress, previously in vitro cultured in media supplemented with 30 g L-1 sucrose and GA3, accumulated more proline and increased peroxidase (POD) activity and the contents of photosynthetic pigments and carbohydrates. For plants previously in vitro cultured with 15 g L-1 sucrose and NAA, no differences were found for proline content and there were reductions in activities of peroxidase (POD), catalase (CAT) and poliphenoloxidase (PPO), and in contents of carbohydrates, with progress of ex vitro water deficit. After rehydration, plants showed physiological recovery, with enzymatic activities and contents of metabolites similar to those found in the controls not submitted to dehydration, regardless of the previous in vitro culture conditions. These results show that micropropagated P. encholirioides has high tolerance to dehydration once in ex vitro conditions, which can ensure the survival of plants from tissue culture when transferred to its natural environment, emphasizing the importance of such biotechnology for the propagation of endangered species.

摘要 本研究针对水分亏缺离体移栽（ex vitro）条件下的雀舌兰属物种Pitcairnia encholirioides，测定了其抗氧化酶（antioxidant enzymes）活性、光合色素（photosynthetic pigments）含量、脯氨酸（proline）含量与碳水化合物（carbohydrates）含量。结果表明：此前在添加30 g·L⁻¹蔗糖与赤霉素3（GA3）的离体（in vitro）培养基中培养的植株，在渐进式水分胁迫下可积累更多脯氨酸，且过氧化物酶（POD）活性、光合色素与碳水化合物含量均显著提升。而此前在添加15 g·L⁻¹蔗糖与萘乙酸（NAA）的离体培养基中培养的植株，其脯氨酸含量未出现显著变化；但随着离体水分亏缺程度加剧，过氧化物酶（POD）、过氧化氢酶（CAT）与多酚氧化酶（PPO）的活性以及碳水化合物含量均有所下降。复水后，无论此前的离体培养条件如何，植株均实现了生理恢复，其酶活性与代谢物含量与未经历脱水的对照组植株无明显差异。本研究结果证实，经微繁殖获得的P. encholirioides在离体移栽条件下具备优异的脱水耐受性，可保障组织培养苗移栽至自然生境后的存活率，凸显了此类生物技术在濒危物种繁育中的重要价值。