Search

Cost-effective tissue culture protocols have been established for the commercial multiplication of three banana varieties, 'Rasthali' (AAB - Silk), 'Grand Naine' (AAA - Cavendish), and 'Udhayam' (ABB - Pisang Awak). Reverse osmosis water and 3% (w/v) table sugar were used as the low-cost water and carbon source, respectively. Six different gelling agent treatments were tested: sago alone (T1), Isabgol alone (T2), sago + agar (T3), Isabgol + agar (T4), sago + Isabgol (T5), and agar alone as a control (T6). Full-strength Murashige and Skoog (MS) medium supplemented with 3 mg l-1 6-benzylaminopurine (BAP) and 1 mg l-1 indole-3-acetic acid (IAA) were used for culture initiation and subculturing. Rooting was accomplished on low-cost MS medium containing 1.0 mg l-1 α-napthaleneacetic acid (NAA), 1.0 mg l-1 indole- 3-butyric acid (IBA), and 250 mg l-1 activated charcoal. Statistical analysis indicated that sago + Isabgol (T5) produced the maximum number of shoots (10 per explant) in 'Udhayam' and 'Rasthali', while sago alone (T1) produced the maximum number of shoots (6 per explant) in 'Grand Naine'. The genetic stability of tissue-cultured banana plantlets produced using these low-cost substitutes was assessed using inter-simple sequence repeat (ISSR) markers. The results indicated that the ISSR profiles of the five treatments and the control (T6) were similar, indicating genetic stability using these cost-effective tissue culture protocols. Reductions in cost over the control (l-1 of MS medium) ranged from 65% to 86%, while the per plant production cost was reduced by 12.5%-20.0%. Adoption of these treatments (T1-T5) as lowcost tissue culture protocols for in vitro propagation would reduce production costs significantly, leading to an expansion of the area planted with tissue-cultured banana, thereby increasing productivity. [ABSTRACT FROM AUTHOR]

In this study, computational prediction of miRNAs from banana EST and BAC sequences was performed, which resulted in the finding of 18 banana miRNAs belonging to 16 miRNA families. For the 18 miRNAs, 25 banana ESTs were found as their potential targets. Most of these targets encode transcriptional factors which play a role in banana development. Additionally, real time PCR assays were performed to profile the expression levels of three miRNAs (miR156, 159 and 166) after the infection of Banana streak Mysore virus (BSMYV). The results showed that symptom severity is correlated to the expression level of miRNAs, and a clear increased expression of miR166 during viral infection. This is the first report to predict and identify miRNAs in banana. [ABSTRACT FROM AUTHOR]

Four protocols viz., the trichloroacetic acid-acetone (TCA), phenol-ammonium acetate (PAA), phenol/SDS-ammonium acetate (PSA) and trisbase-acetone (TBA) were evaluated with modifications for protein extraction from banana (Grand Naine) roots, considered as recalcitrant tissues for proteomic analysis. The two-dimensional electrophoresis (2-DE) separated proteins were compared based on protein yield, number of resolved proteins, sum of spot quantity, average spot intensity and proteins resolved in 4-7 pI range. The PAA protocol yielded more proteins (0.89 mg/g of tissues) and protein spots (584) in 2-DE gel than TCA and other protocols. Also, the PAA protocol was superior in terms of sum of total spot quantity and average spot intensity than TCA and other protocols, suggesting phenol as extractant and ammonium acetate as precipitant of proteins were the most suitable for banana rooteomics analysis by 2-DE. In addition, 1:3 ratios of root tissue to extraction buffer and overnight protein precipitation were most efficient to obtain maximum protein yield.

Activity differences of the first (phenylalanine ammonia lyase, PAL) and the last (cinnamyl alcohol dehydrogenase, CAD) enzymes of phenylpropanoid pathway in the roots of resistant (Yangambi Km5 and Anaikomban) and susceptible (Nendran and Robusta) banana cultivars caused by root lesion nematode, Pratylenchus coffeae, were investigated. Also, the accumulation of phenolics and deposition of lignin polymers in cell walls in relation to resistance of the banana cultivars to the nematode were analyzed. Compared to the susceptible cultivars, the resistant cultivars had constitutively significantly higher PAL activity and total soluble and cell wall-bound phenolics than in susceptible cultivars. The resistant cultivars responded strongly to the infection of the nematode by induction of several-time higher PAL and CAD enzymes activities, soluble and wall-bound phenolics and enrichment of lignin polymers in cell wall and these biochemical parameters reached maximum at 7th day postinoculation. In addition, profiles of phenolic acid metabolites in roots of Yangambi Km5 and Nendran were analyzed by HPLC to ascertain the underlying biochemical mechanism of bananas resistance to the nematode. Identification and quantification of soluble and cell wall-bound phenolic acids showed six metabolites and only quantitative, no qualitative, differences occurred between the resistant and susceptible cvs. and between constitutive and induced contents. A very prominent increase of p-coumaric, ferulic and sinapic acids, which are precursors of monolignols of lignin, in resistant cv. was found. These constitutive and induced biochemical alterations are definitely the chemical defenses of resistant cvs. to the nematode infection.