Rita Megia

Plant regeneration from cultured protoplasts of the cooking banana cv. Bluggoe (Musa spp., ABB group)

SummarySuspensions of embryogenic cells of a triploid banana (Musa spp., cv. Bluggoe) were initiated from the uppermost part of meristematic buds, and used as protoplast source. After 20 weeks in culture, the suspension contained a mixture of globular structures or globules and embryogenic cell clusters, as well as single cells. Two types of protoplasts were obtained from embryogenic suspension culture: small (20–30 μm) and larger (30–50 μm) protoplasts with a dense cytoplasm and large starch grains respectively. The small protoplasts probably originated from embryogenic cell clusters, and also from pseudocambial cells of globules, while larger protoplasts were probably released from oval starchy cells and those of the globule peripheral area. In co-culture with a suitable feeder, consisting of suspensions of diploid banana cells, the protoplasts of triploid banana reformed the cell wall within 24 h and underwent sustained divisions leading to the formation of small clusters of 2–3 cells within 7 days. The latter developed directly into embryos without passing through an apparent callus phase. 10% of such embryos gave rise to plantlets when subcultured in 2.2 μM 6-benzylaminopurine and 2 μM 4 amino-3,5,6-trichloropicolinic acid for 1 week, before transfer to MS medium containing 10 μM 6-benzylaminopurine. The rest of the embryos underwent intensive direct secondary embryogenesis which could lead to the formation of plantlets with a frequency of up to 50% upon further transfer to hormone-free medium.

Callus formation from cultured protoplasts of banana (Musa sp.)

Abstract Protoplasts were isolated from cell suspension initiated from calli of immature seeds of Musa acuminata ssp. burmannica cv Long Tavoy (AA). When co-cultured at high density with a reliable feeder culture, the protoplasts underwent sustained divisions and formed callus. Cytological studies showed that the cells of protoplast-derived calli had embryogenic characteristics as the cell suspensions used as protoplast source. Analysis of isoenzymes, in particular phosphoglucomutase (PGM) and alcohol dehydrogenase (ADH), distinguished the Lolium feeder cells from the protoplast-derived calli of banana and confirmed the Musa nature of these calli. The response of protoplasts depended upon the specificity of the feeder-physical barrier interaction. As a matter of fact, Lolium feeder induced a high rate of growth of protoplast-derived calli when combined with the use of Millipore membrane, used as a physical barrier keeping separate the protoplast culture from the feeder. Banana feeder gave similar results if nylon mesh was used as a physical barrier. The addition of dimethylsulfoxide (DMSO) to the feeder culture neither increased the proliferation of nurse cells nor affected the growth of protoplast-derived calli of banana.

Musa sebagai Model Genom

During the meeting in Arlington, USA in 2001, the scientists grouped in PROMUSA agreed with the launching of the Global Musa Genomics Consortium. The Consortium aims to apply genomics technologies to the improvement of this important crop. These genome projects put banana as the third model species after Arabidopsis and rice that will be analyzed and sequenced. Comparing to Arabidopsis and rice, banana genome provides a unique and powerful insight into structural and in functional genomics that could not be found in those two species. This paper discussed these subjects-including the importance of banana as the fourth main food in the world, the evolution and biodiversity of this genetic resource and its parasite.

Salak (Salacca zalacca (Gaertner) Voss).

Abstract: The salak is an indigenous palm found throughout the Indo-Malaysian region. It is a small spiny palm that grows on moist well drained soil with high organic matter content. The fruit is drupe oval or spindle shaped (like a fig) with a distinct tip, tapering towards the top and rounded at the top end. The skin is covered with regularly arranged scale, creating an appearance similar to that of snake skin, from which the name ‘snake skin fruit’ is derived. The salak is a crunchy fruit that has a taste that combines the flavours of apple, banana, and pineapple. It is a good source of antioxidants that cannot be matched by other tropical fruits.

Musa as a Genomics Model

A number of abiotic stress responsive genes have been identified from various plant species through reverse genetic strategy. A group of genes are involved in plant responses to stress; they are activated by diverse stress conditions and through different mechanisms. One single gene can be induced by several different stress factors; on the other hand, a number of genes can be up-regulated by a single factor. In Physcomitrella patens, through Northern hybridization, the transcript level of the gene GFDD4-I was detected to be markedly increased by ABA, dehydration and cold, but not by salinity and osmotic stress. In Arabidopsis thaliana, a homologous gene to GFDD4-1 namely At2g47770, was confirmed to fulfill similar function as in P. patens: it is inducible by various abiotic stress treatments, i.e. ABA, dehydration, salinity, and cold. Inducible genes in response to abiotic stress factors may be responsible for plant tolerance to those factors.