An efficient protocol for micropropagation of Melaleuca alternifolia Cheel

Abstract

Melaleuca alternifolia is cultivated for the production of an essential oil useful in the cosmetic and pharmaceutical industries. Despite the economic importance of this species, there is little knowledge about its in vitro propagation. The aim of this study was to establish an efficient protocol for micropropagation of M. alternifolia. With the goal of in vitro multiplication by axillary shoot proliferation, both solid and liquid MS and WPM media were tested with supplementation with BA at 0, 0.55, 1.11, 2.22, 3.33, and 4.44 μM. The best result for shoot multiplication was obtained when either 0.55 μM BA was added into solid MS medium or 1.11 μM BA was added into liquid MS medium, with 5.6 and 11.8 shoots per explant generated, respectively. On solid or liquid WPM medium supplemented with 0.55 μM BA, the proliferation rates were 5.5 and 4.7, respectively. Three auxins (NAA, IAA, and IBA) were tested at 0.53 and 2.64 μM during the rooting stage. Several sucrose concentrations (15, 30, and 45 g L −1 ) were compared to a sucrose-free medium. Rooting performances on four culture media were then compared: MS, half-strength MS (MS/2), MS+activated charcoal (AC), and MS/2+AC. The results showed that auxin addition to culture medium is not necessary for in vitro rooting. Rooted microcuttings from different culture media were acclimatized in a greenhouse, and the survival percentage was evaluated. All shoots cultured in an auxinfree MS medium supplemented with sucrose (30 gL −1 ) produced roots, and all plants survived during acclimatization. Activated charcoal added in rooting medium reduced rooting rates.

Micropropagation of a difficult-to-root weeping mulberry (Morus alba var. Shidareguwa): A popular variety for ornamental purposes

“…We found that the presence of auxins was unnecessary for in vitro rooting of 'Shidareguwa' mulberry, which is similar to results for M. acidosa (Enomoto, 1987) and other species (Morimoto et al, 1994;Oliveira et al, 2010). The relationship between auxins, carbohydrates, and rooting is complex and remains unclear.…”

Influence of calcium content of tissue on hyperhydricity and shoot-tip necrosis of in vitro regenerated shoots of Lavandula angustifolia Mill.

“…Anatomical characteristics change in hyperhydric shoots and several types of abnormal structures can be recognized (Ziv 1991). Several factors can induce the hyperhydricity in explants, such as high BAP levels (Oliveira et al 2010), cultivar (Carvalho et al 2013), and agar concentration (Abdoli et al 2007) but the most common cause of the hyperhydricity occurrence is the culture in liquid medium (Scheidt et al 2011;Silva et al 2012). Some species are so sensitive to this physiological change that even when cultivated in solid medium with a low BAP level, hyperhydricity occurs, as it is the case for L. angustifolia.…”

Chlorophyll a fluorescence and growth of Neoregelia concentrica (Bromeliaceae) during acclimatization in response to light levels

“…The roots induced in vitro may be important reserves of carbohydrate, as verified in the bromeliad Aechmea blanchetiana (Baker) LB Smith (Chu et al 2010). However, the roots produced during the in vitro culture stage may have been functionally limited, with impaired water and mineral absorption, even after transfer to ex vitro conditions (Oliveira et al 2010). Thus, the formation of new roots during the ex vitro stages is important (Hazarika 2006) and can be affected by abiotic factors, such as the spectral quality and quantity of light, which are known to stimulate root growth and overall irradiance levels and to affect the accumulation of photoassimilates (Huang et al 2011a).…”