The Effect of Sucrose Supplementation on the Micropropagation of Salix viminalis L. Shoots in Semisolid Medium and Temporary Immersion Bioreactors

Abstract

The effect of sucrose concentration on the micropropagation of axillary shoots of willow was investigated. The following factors were examined: the culture system (semisolid medium in glass jars versus liquid medium in temporary immersion bioreactors), the type of explant (apical and basal sections), the frequency of immersion, and CO2 enrichment. Shoots and leaf growth were significantly higher in RITA® bioreactors than in the jars for all the sucrose treatments. Apical or basal sections of willow cultured in bioreactors under high light intensity (150 µmol m−2 s−1) and ventilated six times a day with CO2-enriched air were successfully proliferated without sucrose, whereas shoots cultured in jars did not proliferate well if sucrose concentration was 0.5% or lower. More roots were formed when sucrose was added to the medium. Shoots cultured in bioreactors were successfully acclimatized irrespective of the sucrose treatment and the root biomass when transferred to ex vitro conditions. This is the first report of photoautotrophic willow micropropagation, our results confirm the importance of proper gaseous exchange to attain autotrophy during in vitro propagation.

Effect of Sucrose on Growth and Stress Status of Castanea sativa x C. crenata Shoots Cultured in Liquid Medium

“…However, in our study with chestnut, we observed a positive correlation between sucrose supplementation and rooting. Similar responses have also been reported in other plants such as grapevine [ 50 ], kiwifruit [ 51 ], Chinese ash [ 52 ], poplar [ 53 ], and willow [ 40 ].…”

“…These authors cultured chestnut shoots in tubes with a semisolid medium and without forced ventilation, and in these conditions shoot growth is frequently sucrose-dependent, as shown for kiwifruit ( Actinidia deliciosa ) [ 36 ], Arabidopsis [ 37 ], Pfaffia glomerata [ 38 ] and Vernonia condensata [ 39 ]. In a recent study we successfully micropropagated willow under high PPF and without sucrose when we used bioreactors ventilated with CO 2 -enriched air instead of jars without ventilation [ 40 ], and to obtain good proliferation in chestnut we applied the same principle, adding CO 2 -enriched air every 90 min to the bioreactors. Increased CO 2 concentration inside the flasks enabled shoot growth of other plants in media with low sucrose or without any supplementary carbohydrate, as reported for Paulownia fortunei (Seem.)…”

Micropropagation of Plum (Prunus domestica L.) in Bioreactors Using Photomixotrophic and Photoautotrophic Conditions

“…It has been reported that this feature promotes the photosynthetic ability of tissues, enabling the decrease or even the elimination of the conventional sugar supplementation [53,54]. For this reason, bioreactors have been used for the photoautotrophic propagation of several plants including eucalyptus [55][56][57][58], apple [59], poplar [60], bamboo [61] and willow [62], but to the best of our knowledge there are no reports of photoautotrophic protocols for plum or any other Prunus species. In the current study, we explored the feasibility of using commercial RITA© bioreactors for the propagation of plum photoautotrophically (without exogenous sugars) in an experimental unit which provided good results with willow [62].…”

“…For this reason, bioreactors have been used for the photoautotrophic propagation of several plants including eucalyptus [55][56][57][58], apple [59], poplar [60], bamboo [61] and willow [62], but to the best of our knowledge there are no reports of photoautotrophic protocols for plum or any other Prunus species. In the current study, we explored the feasibility of using commercial RITA© bioreactors for the propagation of plum photoautotrophically (without exogenous sugars) in an experimental unit which provided good results with willow [62]. Previously, we carried out some experiments photomixotrophically (using 3% sucrose) to find the best growing conditions for the plum genotypes under study.…”

“…Increasing exposure of the plant material to more immersions of up to six per day increased plant growth, whereas using more frequent immersion produced hyperhydric shoots (data not shown). Immersion every 3-6 h has been successfully used for other tree species such as calabash tree [39], Fraxinus mandshurica [65], teak, chestnut [45], yerba mate [47], willow [48,62] and apple [66].…”