Proline levels, oxidative metabolism and photosynthetic pigments during in vitro growth and acclimatization of Pitcairnia encholirioides L.B. Sm. (Bromeliaceae)

Abstract

This study aimed to evaluate the variation in the levels of proline, oxidative metabolism and photosynthetic pigments in plants of Pitcairnia encholirioides grown in vitro under different conditions and after acclimatization. The analyses were performed after 150 days of in vitro cultivation in MS media supplemented with 10 µM GA 3 or 0.2 µM NAA, sucrose at 15 or 30 g L -1 , in test tubes which allowed gas exchange or in a hermetically sealed system, and 180 days after acclimatization. The in vitro maintenance in hermetically sealed flasks, with GA 3 and 15 g L -1 sucrose had adverse metabolic effects, which was demonstrated by the lower proline and photosynthetic pigments accumulation and by the increase in antioxidant enzymes activities. After acclimatization, differences for proline and photosynthetic pigments were no longer found and the enzymatic activities ranged unevenly. The results suggest that the in vitro cultivation in media with 0.2 µM NAA and 30 g L -1 sucrose, in test tubes capped with closures which allowed gas exchange, is more suitable for micropropagation of P. encholirioides, providing a prolonged maintenance of in vitro cultures and plantlets with superior quality for ex vitro development.Keywords: enzymatic activity, oxidative stress, micropropagation, proline. Niveis de prolina, do metabolismo oxidativo e dos pigmentos fotossintéticos durante o crescimento in vitro e aclimatização de Pitcairnia encholirioides L.B. Sm. (Bromeliaceae) ResumoEste trabalho objetivou avaliar a contribuição da prolina, do metabolismo oxidativo e dos pigmentos fotossintéticos na propagação in vitro e aclimatização de Pitcairnia encholirioides, uma bromélia criticamente ameaçada de extinção. As análises foram realizadas após 150 dias de cultivo in vitro em meio MS suplementado com 10 µM de GA 3 ou 0,2 µM de ANA, 15 ou 30 g L -1 de sacarose, em tubos de ensaio que permitiam trocas gasosas ou em sistema hermeticamente vedado, e também 180 dias após aclimatização. A manutenção in vitro em frascos hermeticamente fechados, com GA 3 e 15 g L -1 de sacarose apresentou efeito metabólico adverso, demonstrado pelo menor acúmulo de prolina e pigmentos fotossintéticos e também pelo aumento das atividades de enzimas antioxidantes. Após aclimatização, as diferenças para prolina e pigmentos fotossintéticos não foram mais encontradas e as atividades enzimáticas variaram de maneira desuniforme. Os resultados sugerem que o cultivo in vitro em meio com 0,2 µM de ANA e 30 g L -1 de sacarose, em tubos fechados com tampas que permitem trocas gasosas, é mais adequado para a micropropagação de P. encholirioides, proporcionando uma manutenção prolongada das culturas in vitro e plântulas com qualidade superior para o desenvolvimento ex vitro.Palavras-chave: atividade enzimática, estresse oxidativo, micropropagação, prolina.

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

“…The objective of this study was to investigate the activities of antioxidant enzymes, proline, carbohydrates and photosynthetic pigments accumulation in leaves of micropropagated P. encholirioides subjected to water stress and after rehydration, in order to increase the survival of this species in ex vitro conditions. This work complements the data obtained by our research group with P. encholirioides in vitro and under acclimatization (Resende et al, 2016b), the only work in literature, to our knowledge, that addresses physiological traits of this species.…”

“…were previously established in vitro from seeds collected in the natural environment in Santa Maria Madalena, Rio de Janeiro State, Brazil. Conditions of in vitro and acclimatization phases performed here were described by Resende et al (2016b). The seedlings grew in test tubes (2.5 x 15 cm) filled with MS basal medium (Murashige and Skoog, 1962) supplemented with 10 µM gibberellic acid (GA 3 ) or 0.2 µM α-naphthalene-acetic acid (NAA), and sucrose at 15 or 30 g L -1 , with 7 g L -1 agar, in all possible combinations.…”

In vitro arrow cane (Gynerium sagitatum Aubl.) multiplication in double phase medium

“…Because of this external energetic support, when transferred to ex vitro conditions, plants must have plenty of carbohydrate reserves in organs, such as leaves and stems, that serve as "life boat" effect before newly photosynthetic active leaves are formed. Therefore, micropropagated plants with larger organs will store more nutritional reserves and will have more opportunities to successfully withstand adaptation when transferring to natural environment (Kane, 1996;Resende et al, 2016;Zakavi et al, 2016).…”

Physiological responses by Billbergia zebrina (Bromeliaceae) when grown under controlled microenvironmental conditions

“…The application of plant tissue culture techniques to in vitro propagation of bromeliads has been reported previously (Huang et al, 2011;Martins et al, 2014;Resende et al, 2016;Viehmannova et al, 2016). Most of these studies are related to the use of plant growth regulators as major modulators of in vitro morphogenetic responses.…”