Anatomical and physiological modifications of micropropagated 'Caipira' banana plants under natural lighy

Abstract

Research about the use of natural light associated to changes in sucrose levels demonstrated potential in promoting in vitro hardiness of tropical climate species, as well as reducing production costs. However, little is known about physiological and structural changes that happen in the process. This study evaluated the physiological and anatomic performance, and ex vitro survival of micropropagated banana plants in response to cultivation conditions, in the stage of in vitro rooting. Shoots of the 'Caipira' cultivar were cultivated in MS medium, supplemented with 1 mg L -1 NAA and 6 g L -1 agar, in which the following treatments were applied: two sucrose concentrations (15 g L -1 or 30 g L -1) and two cultivation conditions (Natural light -greenhouse and Artificial light -growth chamber). At the end of 45 days, the contents of chlorophyll a, b and total, the relative water content in the tissues, anatomic characteristics and the ex vitro survival were evaluated. Effects of growth environment and sucrose concentration were observed on micropropagated 'Caipira' banana anatomy, physiology and survival. In vitro rooting of the shoots under natural light in the medium containing 15 g L -1 or 30 g L -1sucrose promoted major alteration in the increase of palisade and spongy parenchyma, as well as reducing leaf water loss and plant death. The results obtained in the present study confirm the potential of the use of natural light as a substitute for artificial light for micropropagation of tropical species. Key words: Musa spp., solar light, carbohydrate, water loss, anatomy MODIFICAÇÕES ANATÔMICAS E FISIOLÓGICAS DE BANANEIRAS 'CAIPIRA' MICROPROPAGADAS SOB LUZ NATURALRESUMO: Pesquisas acerca do uso da luz natural associado a alterações nos níveis de sacarose têm apresentado potencial para promover a rustificação in vitro de espécies de clima tropical bem como reduzir os custos de produção. Todavia, pouco se conhece sobre as modificações fisiológicas e estruturais ocasionadas. Avaliaram-se o comportamento fisiológico, anatômico e a sobrevivência ex vitro de bananeiras micropropagadas em resposta às condições de cultivo, na fase de enraizamento in vitro. Para isso, brotações axilares da cultivar Caipira foram cultivadas em meio MS, adicionado de ANA (1 mg L ) e dois ambientes de cultivo (Luz natural -casa de vegetação e Luz artificial -sala de crescimento). Ao final de 45 dias, foram avaliados os teores de clorofila a, b e total, conteúdo relativo de água nos tecidos, características anatômicas e a sobrevivência ex vitro. Houve efeito do ambiente de cultivo e concentrações de sacarose sobre a anatomia, fisiologia e sobrevivência de plantas de bananeira 'Caipira' micropropagada. O enraizamento in vitro das brotações sob luz natural e meio contendo 15 g L -1 ou 30 g L -1 de sacarose promove como principais alterações o aumento na espessura dos parênquimas paliçádico e esponjoso, bem como reduz a perda de água foliar e morte de plantas. Os resultados alcançados no presente estudo confirmam o potencial da luz natur...

Photosynthetic and leaf anatomical characteristics of Castanea sativa: a comparison between in vitro and nursery plants

“…The anatomy of in vitro microshoot leaves, such as reduced mesophyll differentiation and thin cuticle with scarce wax deposition, exhibited typical features described in other in vitro plants (Johansson et al 1992, Apóstolo andLlorente 2000). The nursery plant leaves had both, a thick and well developed palisade parenchyma that according to Costa et al (2009) indicates an adaptation to greater PFD. The leaves of in vitro microshoots developed a dense and thin palisade parenchyma without air spaces in the spongy mesophyll (Fig.…”

Confirmation of “pre-plasmolysis mediated ex-osmosis hypothesis” to obtain shoot bud morphogenesis in Catharanthus roseus

“…However, the guard cell turgor regulation against osmotic stress is even more complicated. While picking the leaves for the experimentation the stomata were opened conceivably due to the hindered gaseous exchange from the mouth-space of the culture vessel and to maintain the equilibrium with ambient in vitro environment, the stomata remained open [ 2 ]. Verma and Mathur [ 13 ] also proposed that plasmolysis of leaves with hypertonic mannitol solution before culturing over the shoot induction media to get the support of ex-osmosis to reduce toxic metabolites inside the cells.…”

Micro‐morpho‐anatomical mechanisms involve in epiphytic adaptation of micropropagated plants of Vanda tessellata (Roxb.) Hook. ex G. Don

“…The hardening and acclimatization steps determine the successful development of micropropagation protocol for V. tessellata and considered as a maturation phase. At this stage, the in vitro induced anatomical and micro‐morphological aberrations of the plants undergo alterations and develop similar structures to those of the mother plants for possible survival in the field (Costa et al, 2009).…”

“…The sequential micro‐morpho‐anatomical evaluation at subsequent stages of micropropagation and careful acclimatization procedures paves the way for the developmental transition of plants towards maximum survival success in the field (Costa, Pasqual, Pereira, & de Castro, 2009; Pospisilova et al, 2007). Specifically, the proper development of velamen tissues around the roots of epiphytic orchids is most important for their adaptive mechanism towards changed environmental conditions (Zotz & Winkler, 2013).…”