Taxonomic value of calcium oxalate cystals in Musa germplasm

Epidermal and histological characterization of Musa species and cultivars were carried out to investigate the descriptor value of calcium oxalate between groups and subgroups of cultivars. Epidermal peels of the bracts of selected plantain and banana cultivars stained with 0.01% safranin solution and permanent mounts of microtometric sections of fruits, bracts and peduncles stained with hydrogen peroxide and silver nitrate were microscopically examined for their crystal content and features. Bract epidermal features discriminate between the ‘AAB' plantains and ‘AAA' bananas. The major form of occurrence of calcium oxalate in the vegetative and reproductive tissues is bundle raphide. The bract adaxial epidermic of bananas show the occurrence of raphide idioblasts which contain a bundle raphide each. The idioblasts and bundles are more-or-less absent in the plantain bracts. Calcium oxalate occurs in the fruit peel as bundle raphides and in the pulp as intra-amylar crystals. Histological characterization of Musa germplasm helps to elucidate the limits of diversity in the germplas

Ploidy variation in hybrids from interploid 3x X 2x crosses in Musa

Hybrids were obtained after in vitro germination of embryos from interploid crosses between triploid ‘French' plantain cultivars (Musa spp. AAB group). ‘Ntanga 2' and ‘Bobby Tannap' with diploid banana (Musa acuminata subsp. burmannicoides) ‘Calcutta 4'. Cross-pollinated bunches were harvested at full maturity and ripened with acetylene in a room for 4 days. Seeds were extracted from peeled ripe fruits by squashing. Embryos from the seeds were excised aseptically after 2 days and germinated in vitro. Seedlings were subsequently planted in early evaluation trials after acclimatizing in the greenhouse. Chromosome counts were carried out on root tips of mature and maiden suckers to determine ploidy levels using a modified squashing technique. Counts showed that two of the hybrids were aneuploids (trisomics) with somatic chromosome number of 2n = 2x + 1 = 23. One hybrid was diploid while the other two were tetraploids. Tetraploids are the most promising hybrids for the genetic improvement of plantains. Diploids are valuable material for further improvement of the plantain genome at this ploidy level. Trisomics provide means for further characterization of the Musa genome and physical gene mapping in plantain and banana

Multivariate pattern of quantitative trait variation in triploid banana and plantain cultivars

Plantains and bananas (Musa spp. L.) are inter- or intraspecific triploid hybrids derived from crosses between M. acuminata Colla. (A genome) and M. balbisiana Colla. (B genome). Cultivars have been assigned to different taxonomic groups (AA, BB, AAA, AAB, ABB, etc.) based on morphological qualitative descriptors. Principal component analysis of 15 quantitative traits was carried out to establish a more objective taxonomic relationship of cultivar groups and subgroups in the Musa germplasm. Fruit traits, number of neutral flowers, total number of leaves, plant girth at 50 cm, and days to flowering and harvest were the major discriminating traits in the germplasm. Principal components analyses grouped Musa germplasm into AAB plantains, AAA dessert bananas and ABB cooking bananas. The AAB starchy bananas appear to be separated into two subgroups with one being close to the AAB plantains and the other being close to the ABB cooking bananas. The dwarf French AAB plantain cultivar ‘Njock Kon' appears to be a mutant of a giant AAB plantain cultivar