Oligonucleotide and amplification fingerprinting of wild species and cultivars of banana (Musa spp.).

DNA oligonucleotide and amplification fingerprinting have been successfully used to detect genetic polymorphisms in 15 representative species and cultivars of the genus Musa, comprising AA, AAA, AAAA, AAB, ABB, and BB genotypes. In-gel-hybridization of Hinf I-digested genomic banana DNA to the 32P-labeled synthetic oligonucleotides (GATA)4, (GTG)5, and (CA)8 revealed considerable polymorphisms between Musa species and cultivars. The fingerprint patterns proved to be somatically stable and did not show differences between individual plants of 'Grand Nain' (AAA genotype). Dendrograms based on oligonucleotide fingerprint band sharing data proved to be consistent with most of the known features of the history of banana and plantain cultivation and evolution, respectively. DNA samples from the same banana species and cultivars were also amplified by PCR using single or pairwise combinations of short oligonucleotide primers. Amplification products were separated on agarose or polyacrylamide gels and visualized by ethidium bromide or silver staining, respectively. Polymorphic patterns were obtained with some but not all primers. By using the CCCTCTGCGG primer in simplex and/or duplex PCR, the induced mutant 'GN60A' was clearly recognized from its original variety 'Grand Nain'. Both fingerprint techniques allowed the detection of bands characteristic for the A and B genome. This DNA fingerprinting technology has potential application in several areas of Musa improvement.

Regeneration of Ensete ventricosum through somatic embryogenesis and adventitious buds.

In southern and south-western Ethiopia, Ensete ventricosum is grown as an important starchy, staple food crop, supporting the diet of a quarter of the Ethiopian population. Due to difficulty in germinating seeds and the long vegetative period, breeding enset is extremely difficult. Adventitious buds and somatic embryos have been induced from callus derived from corm tissues and cultured on Murashige and Skoog's (MS) basal medium supplemented with benzylaminopurine (BAP) or 6 γ-γ-dimethylallylamino purine 2iP. Elongation of somatic embryos was achieved on the same medium and rooting was induced on half-strength MS basal medium supplemented with IBA. No phenotypic variation was observed among more than 200 potted regenerants. The possible implications for mutation breeding in this crop are discussed.

Somatic embryogenesis from cultured leaf segments of Zea mays.

Basal leaf segments of 3 to 4 week old maize (Zea mays L.) seedlings plated on SH medium with 30 µM dicamba produced embryogenic callus and/or somatic embryos. Histological evidence showed that some of the embryos arose directly from the explant. When leaf segments with embryos were transferred to MS medium with 1.0 µM NAA, 1.0 µM IAA, 2.0 µM 2iP, and 60 g/l sucrose, the embryos germinated and the resulting seedlings could be established in culture tubes. These responses were obtained from three inbred lines, CHI31, S615, and S7.

Effect of spikelet position on rice anther culture efficiency.

The potential of anthers from different parts of the panicle to induce callus was investigated with the japonica rice variety Taipei 309. The results showed that the callusing abilities of anthers from different spikelet positions were significantly different. After plating 4483, 4496, 4348 anthers from the basal, middle and top parts, the percentage of anthers forming calli was 20% in the basal part, 12% in the middle part and 8% in the top part. The anthers of basal parts containing pollen at all uninucleate stages, including early, middle and late, showed higher callus induction frequency than those from middle and top parts. The green plantlet regeneration frequencies of top, middle and basal spikelets were around 18% in all three cases. From the results it would appear that anthers from the basal part of the panicle should be used in anther culture of rice in order to obtain higher efficiencies, and thereby optimise the usefulness of this technique in rice breeding programmes.