Improved callogenesis and plant regeneration from immature male flowers of East African highland banana cv. \u201cNakitembe\u201d (AAA-EA)

Application of biotechnological tools in breeding, germplasm conservation and propagation of the East African bananas ( Musa sp.) is limited by the crop\u2019s recalcitrance to somatic embryogenesis. This study was undertaken to establish an efficient callus induction and plant regeneration protocol from immature male flowers in the most commercial and farmer preferred banana cultivar \u201cNakitembe\u201d. Embryogenic callusing was improved from 2.9% on conventional MA1 culture medium to 4.2% with 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline and 300 mg L-1 casein hydrolysate supplements. A combination of the three amino acids with Chui N6 salts yielded the highest callusing of 10.2%. Cell suspensions were developed and maintained on conventional MS based MA2 medium. Subsequently, the highest efficiency of embryos germination (up to 80%) was achieved on MA4 medium, supplemented with 2.25 mg L-1 BAP and 0.2 mg L-1 IAA. The developed protocol has been successfully applied in Agrobacterium mediated genetic transformations of this variety.L\u2019application des outils biotechnologiques dans la s\ue9lection, la conservation du mat\ue9riel g\ue9n\ue9tique et la propagation des bananiers d\u2019Afrique de l\u2019Est ( Musa sp.) est limit\ue9e par la r\ue9ticence de la culture \ue0 l\u2019embryogen\ue8se somatique. Cette \ue9tude a \ue9t\ue9 entreprise pour \ue9tablir un protocole efficace d\u2019induction des cals embryog\ue8nes et de r\ue9g\ue9n\ue9ration des plantes \ue0 partir de fleurs m\ue2les immatures dans le cultivar de bananier le plus commercial et pr\ue9f\ue9r\ue9 des agriculteurs \uab Nakitembe \ubb. Les callosit\ue9s embryog\ue8nes ont \ue9t\ue9 am\ue9lior\ue9es de 2,9% sur le milieu de la culture MA1 conventionnel \ue0 4,2% avec des suppl\ue9ments de 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline et 300 mg L-1 d\u2019hydrolysat de cas\ue9ine. Une combinaison des trois acides amin\ue9s avec des sels de Chui N6 a donn\ue9 le cal embryog\ue8ne le plus \ue9lev\ue9 de 10,2 %. Des suspensions cellulaires ont \ue9t\ue9 d\ue9velopp\ue9es et maintenues sur un milieu MA2 \ue0 base de MS conventionnel. Par la suite, l\u2019efficacit\ue9 la plus \ue9lev\ue9e de la germination des embryons (jusqu\u2019\ue0 80 %) a \ue9t\ue9 obtenue sur le milieu MA4 compl\ue9t\ue9 par 2,25 mg L-1 de BAP et 0,2 mg L-1 d\u2019IAA. Le protocole d\ue9velopp\ue9 a \ue9t\ue9 appliqu\ue9 avec succ\ue8s dans les transformations g\ue9n\ue9tiques induites par Agrobacterium de cette vari\ue9t\ue9

Improved callogenesis and plant regeneration from immature male flowers of East African highland banana cv. “Nakitembe” (AAA-EA)

Application of biotechnological tools in breeding, germplasm conservation and propagation of the East African bananas (Musa sp.) is limited by the crop’s recalcitrance to somatic embryogenesis. This study was undertaken to establish an efficient callus induction and plant regeneration protocol from immature male flowers in the most commercial and farmer preferred banana cultivar “Nakitembe”. Embryogenic callusing was improved from 2.9% on conventional MA1 culture medium to 4.2% with 500 mg L-1 L-Glutamine, 500 mg L-1 L-Proline and 300 mg L-1 casein hydrolysate supplements. A combination of the three amino acids with Chui N6 salts yielded the highest callusing of 10.2%. Cell suspensions were developed and maintained on conventional MS based MA2 medium. Subsequently, the highest efficiency of embryos germination (up to 80%) was achieved on MA4 medium, supplemented with 2.25 mg L-1 BAP and 0.2 mg L-1 IAA. The developed protocol has been successfully applied in Agrobacterium mediated genetic transformations of this variety

Suppression of the ubiquitin E2 gene through RNA interference causes mortality in the banana weevil, Cosmopolites sordidus (Germar)

RNA interference (RNAi) is a natural defense mechanism triggered by double-stranded RNA (dsRNA) for protection of cells against foreign parasitic nucleic acids. The RNase III enzyme Dicer processes dsRNAs into short small interfering RNAs (siRNAs) that degrade the specific mRNA. RNAi has been demonstrated in a range of organisms including coleopterans and has a potential use in crop protection against insect pests and pathogens. In this study, we explored the use of RNAi for the control of the banana weevil that is not only the most important banana pest in East Africa, but has also eluded control through cultural, chemical and biological approaches. The ubiquitin E2 gene, essential for protein catabolism was identified, amplified and transcribed into dsRNA and fed to banana weevil larva in in vitro bioassays. The dsRNA significantly retarded banana weevil larval growth and caused up to 100% mortality at 21 days. Growth inhibition and mortality increased with dsRNA concentration (10 to 100 ng µL-1), though no significant differences were observed between the 50 and 100 ng µL-1 concentrations. We for the first time demonstrate RNAi in the banana weevil. Transgenic banana plants expressing siRNA or hairpin RNA could therefore potentially be used for controlling the banana weevil