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

C F Resende,V F Braga,P H P Peixoto,V F Vale,P F Pereira,C J Silva,R E Bianchetti,C Ribeiro,R C Forzza

doi:10.1590/1519-6984.19314

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 GA3 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 GA3 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.

Highlights

In Brazil, bromeliads are popular ornamental plants often used in public and private gardens (Versieux and Wendt, 2007)
Significant differences were found only in materials from plantlets maintained in culture media supplemented with naphthalene-acetic acid (NAA), with high proline contents in tissues kept in the presence of 30 g L–1 sucrose, regardless the type of closure
The differences found in plants maintained in culture media supplemented with NAA, with high proline contents in tissues kept with 30 g L–1 sucrose, regardless the type of closure seems to be a result of the osmotic adjustment in response to hydric stress caused by the high sucrose level in culture media

Summary

Introduction

In Brazil, bromeliads are popular ornamental plants often used in public and private gardens (Versieux and Wendt, 2007). Pitcairnia encholirioides L.B. Sm. is a quite rare bromeliad. In 2004, a population of around 900 plants was found on a much degraded rocky outcrop, in an area subject to fire and trampling by animals, located in Santa Maria Madalena, RJ, Brazil, suggesting that this species was among the most threatened in Rio de Janeiro (Martinelli and Forzza, 2006). This species was included by the Biodiversitas Foundation in the critically endangered category (FUNDAÇÃO BIODIVERSITAS, 2005)

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