The sequence-related amplified polymorphism (SRAP) technique, aimed for the amplification of open reading frames (ORFs), vis-â-vis that of the amplified fragment length polymorphisms (AFLP) were used to analyze the genetic variation and relationships among forty Musa accessions; which include commercial cultivars and wild species of interest for the genetic enhancement of Musa. A total of 403 SRAP and 837 AFLP amplicons were generated by 10 SRAP and 15 AFLP primer combinations, of which 353 and 787 bands were polymorphic, respectively. Both cluster analysis of unweighted pair-grouping method with arithmetic averages (UPGMA) and principal coordinate (PCO) analysis separated the forty accessions into their recognized sections (Eumusa, Australimusa, Callimusa and Rhodochlamys) and species. The percentage of polymorphism amongst sections and species and the relationships within Eumusa species and subspecies varied between the two marker systems. In addition to its practical simplicity, SRAP exhibited approximately threefold more specific and unique bands than AFLP, 37 and 13%, respectively. SRAP markers are demonstrated here to be proficient tools for discriminating amongst M. acuminata, M. balbisiana and M. schizocarpa in the Eumusa section, as well as between plantains and cooking bananas within triploid cultivars.

No abstract

The water soluble carbohydrates (WSC) glucose, fructose, and sucrose are well-known to the great public, but fructans represent another type of WSC that deserves more attention given their prebiotic and immunomodulatory properties in the food context. Although the occurrence of inulin-type fructo-oligosaccharides (FOS) was proposed in the fruit of some banana accessions, little or no information is available neither on the exact identity of the fructan species, nor on the fructan content in different parts of banana plants and among a broader array of banana cultivars. Here, we investigated the WSC composition in leaves, pulp of ripe fruits and rhizomes from mature banana plants of 11 accessions (I to XI), including both cultivated varieties and wild Musa species. High performance anion exchange chromatography with integrated pulsed amperometric detection (HPAEC-IPAD) showed the presence of 1-kestotriose [GF2], inulobiose [F2], inulotriose [F3], 6-kestotriose and 6G-kestotriose (neokestose) fructan species in the pulp of mature fruits of different accessions, but the absence of 1,1-nystose and 1,1,1 kestopentaose and higher degree of polymerization (DP) inulin-type fructans. This fructan fingerprint points at the presence of one or more invertases that are able to use fructose and sucrose as alternative acceptor substrates. Quantification of glucose, fructose, sucrose and 1-kestotriose and principal component analysis (PCA) identified related banana groups, based on their specific WSC profiles. These data provide new insights in the biochemical diversity of wild and cultivated bananas, and shed light on potential roles that fructans may fulfill across species, during plant development and adaptation to changing environments. Furthermore, the promiscuous behavior of banana fruit invertases (sucrose and fructose as acceptor substrates besides water) provides a new avenue to boost future work on structure-function relationships on these enzymes, potentially leading to the development of genuine banana fructosyltransferases that are able to increase fructan content in banana fruits.

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The mite Raoiella indica Hirst was recently introduced into America, where it has shown amazing ability to disseminate and broaden its range of hosts. An experiment was conducted in Cancún, Mexico, to determine infestation levels of this mite on plants recorded as hosts: coconut palm (Cocos nucifera) of cultivars Pacific Tall and Malayan Dwarf, oil palm (Elaeis guineensis) hybrids Deli x Ghana and Deli x Nigeria, Dwarf Giant banana (Musa acuminata, AAA subgroup Cavendish), Horn plantain (M. acuminata x Musa balbisiana, AAB subgroup Plantain), lobster claw (Heliconia bihai), and red ginger (Alpinia purpurata). Nursery plants of these host species or cultivars were artificially infested with R. indica in February 2011. In the four replications of 10 plants, each plant was infested with 200 R. indica specimens, and the numbers of infesting mites were recorded for 6 months. A maximum of 18,000 specimens per plant were observed on coconut Pacific Tall and Malayan Dwarf, followed by lobster claw, with a maximum of 1000 specimens per plant. Infestations were minimal for the remaining plants. Mite numbers on all plants declined naturally during the rainy season. All plant materials sustained overlapping mite generations, indicating that they are true hosts. Complementarily, infestation level was determined in backyard bananas and plantains. Correlations of infestation with plant height, distance from coconuts, and exposure to direct sunlight were estimated. Both bananas and plantains were infested by R. indica even when situated far from infested coconut palms. A Spearman correlation was found between infestation and plant height, although it was significant only for Silk plantain.