Five different liquid medium culture methods for meristem propagation of bananas were investigated and compared with solid medium culture. Treatments studied were: gelled culture medium (treatment 1); liquid medium with immersion of the plants (treatment 2); liquid medium with cellulose culture support (treatment 3); liquid medium with partial immersion of the plants (treatment 4); liquid medium aerated by bubbling (treatment 5); liquid medium with temporary immersion of the explants for 20 min every 2h (treatment 6). After 20 days of culture, three culture groups with statistically different multiplication rates were observed: -shoots in simple liquid medium and those on cellulose substrate proliferated little or not at all, -shoots on gelled medium, those subjected to partial immersion and those in aerated medium displayed multiplication rates of 2.2 to 3.1, and -the highest multiplication rate (>5) was observed in explants subjected to temporary immersion in the medium. Two groups of treatments differed in the accumulation of dry matter: the smallest weight (around 0.5 g) was observed in treatments 1, 2, 3 and 4, and accumulation was 2 to 5 times greater in the explants in aerated liquid medium and those subjected to temporary immersion. The highest multiplication rates and weight gains were observed in aerated treatments (treatments 4 and 5). Shoots in liquid medium continuously aerated by bubbling displayed hyperhydricity of the outer leaf sheaths. This was not observed with temporary immersion of explants.

ant, J, V, 1996, Embryogenic cell suspensions from tiie male flower of Musa AAA cv. Grand nain. -Physiol, Plant, 97; 285-290, There are very few reports on the establishment of iong-term embrj'ogenic cell cuitures of banana, especially of triploid cultivars of commercial interest, Embryogenic cell suspensions were prepared using the cuitivar Grand nain, the most widely grown dessert banana in the world. After culture for 5 or 6 months of immattire male flowerbuds adjacent to the floral apex, yeilow, compact calluses and white, friable embrj'Ogenic tissues were induced. Suspension cultures were initiated ffom embryogenic tissues placed in liquid medium. The packed cell volume (PCV) of the suspensions increased 2-to 5-fold with each monthly culture cycle. Plating of tiie embryogenic suspensions resulted in approximately 370X10' embrj'os per ml of PCV, Depending on the size of embryos, 3 to 20% germination was observed, A histological survey of cell suspensions and embryo development was carried out. Cellular aggregates with cells displaying typical embryogenic features were formed. Most of the somatic embiyos were probably of unicellular origin. ), R. Domergue, S. Monmarson, J. Schwendiman and C Teisson. CIRAD-FLHOR. Laboratoire BIOTROP. B.P. 5035. Av. du val de Montferrand,

No abstract

Banana streak virus (BSV) is causing increasing concern in almost every producing area of banana and plantain (Musa spp.) worldwide. This situation appeared partially linked to some breeding lines and micropropagated hybrids. A complete BSV sequence integrated into the genome of a triploid plantain has been recently characterised and it has been hypothesised that it could give rise to infectious virus via recombination. In this study, we evaluated the effect of a routine micropropagation procedure on the expression of BSV in the FHIA 21 tetraploid hybrid. The widespread presence of integrated sequences and the absence of episomal BSV in thirty FHIA 21 "mother plants" selected for micropropagation were first confirmed by specific PCR and IC-PCR tests. The proliferation stage of the procedure, characterised by an intensive production of neoformed buds, appeared determinant in BSV expression whereas the rooting and acclimatisation stages had little or no effect. The duration in culture and the way of subdividing the clumps of proliferation influenced greatly the percentage of episomal BSV infections, reaching 58% of infected micropropagated lines after six in vitro subcultures. These data suggest that the expression of episomal BSV observed during the in vitro procedure is correlated with the presence of an integrated form.

No abstract