Effect of Bap, Naa and Ga3, Either Alone or in Combination, on Meristem Culture and Plantlet Establishment in Sweet Potato (Cv Brondal)

Abstract

In Zimbabwe, the average sweet potato yield (6 t/ha) is relatively low when compared to Asian counterparts (17 t/ha). These low crop yields have been blamed on weevil infestations and viral infections which account for 60-90% of sweet potato yield losses in Africa. Meristem tip culture, a Centre for Potato Improvement (CIP) initiated tissue culture technique, has been widely used to eradicate viruses from clonally propagated crops and has been noted to be one of the instrumental techniques that helped China to increase sweet potato yields. In an effort to adopt the meristem tip culture technique for the production of virus-free planting material of a local sweet potato (cv Brondal), a study was conducted to evaluate the effect of Benzylamino purine (BAP), 1-Naphthaleneacetic acid (NAA) and Gibberellic acid (GA3) (either alone or in combination) on cultured Brondal meristems. The different hormonal treatments were assessed on the following parameters: plantlet regenerative capacity, multiple plantlet production, shoot height, average leaf number per shoot and average node number per shoot, ten weeks after meristem culture. All treatments containing a combination of BAP (1 mg -L) and GA3 (at either 5 mg -L, 10 mg -L, or 20 mg -L) had a significantly (p<0.01) higher plantlet regenerative capacity of 33-66% when compared to other treatment combinations. Only treatments, 10 mg -L GA3 + 1 mg -L BAP and 20 mg -L GA3 + 1 mg -L BAP were capable of inducing multiple plantlet formation, producing an average of three plantlets/meristem and two plantlets/meristem respectively. Overall, treatment 10 mg -L GA3 + 1 mg -L BAP gave rise to significantly (p<0.01) taller shoots (20 mm) compared to the rest of the treatments used. For average leaf number per shoot, all GA3 treatments (5 mg -L, 10 mg -L, or 20 mg -L) supplemented with 1 mg -L BAP gave significantly (p<0.01) higher numbers of leaves (six leaves/shoot) than the rest of the treatments. Treatments 10 mg -L GA3 + 1 mg -L BAP and 20 mg -L GA3 + 1 mg -L BAP gave rise to the highest number of nodes per shoot, producing an average of three nodes per shoot. In sharp contrast to treatments containing a combination of BAP and GA3, all treatments containing a combination of BAP and NAA performed poorly in all parameters tested for plant regeneration of Brondal sweet potato variety. In conclusion, the best hormonal treatment for culturing Brondal meristems proved to be 10 mg -L GA3 + 1 mg -L BAP.

Optimization of media formulation for axillary shoot multiplication of the red-peeled sweet potato (Ipomoea batatas [L.] Lam.) &#8216;Abees&#8217;

“…A previous study (El Far, 2007) found that neither IAA, NAA, nor GA3 enhanced shoot proliferation in 'Abees' sweet potato but that GA3 enhanced shoot elongation. However, the combination of high concentration GA3 (10 mg L -1 ) and 2 mg L -1 BA improved adventitious shoot regeneration in 'Brondal' sweet potato to a mean of three shoots per meristem, with three nodes per shoot (Masekesa et al, 2016). Although silver nitrate has been used widely as an additive for in vitro propagation (Kumar et al, 2009), it failed to improve shoot multiplication in 'Abees' sweet potato, and although the combination of 2 mg L -1 BA and 100 mg L -1 oxalic acid significantly increased shoot number, maximum shoot length was observed on the medium that was supplemented with oxalic acid (200 mg L -1 ) alone.…”

Phytotoxicity and Other Adverse Effects on the In Vitro Shoot Cultures Caused by Virus Elimination Treatments: Reasons and Solutions

“…cultivar, while addition of 1 mg/L BA alone to medium induced the shoot regeneration at about a 1% rate. The presence of BA either alone or combined with NAA or GA 3 was proven to be necessary for shoot initiation [ 64 ]. BA level was crucial to increase the shoot initiation percentage of other cultivars of sweet potato ( I. batatas (L.) Lam.…”

“…cultivar; regardless, there were no significant differences between shoot regeneration capability of meristems cultured on media with 5.0, 10.0, and 20.0 mg/L GA 3 content. However, the most shoots were obtained on the medium containing 10.0 mg/L GA 3 due to multiplied shoots developed on meristems [ 64 ].…”

“…In any case, the higher number of shoots was accompanied by a decrease in the length of the shoots [ 58 ]. In the case of ‘Brondal’ sweet potato ( I. batatas L. Lam) cultivar, the significantly longest shoots (up to 20 mm) developed on medium supplemented with 10.0 mg/L GA 3 , compared to those shoots (<14 mm) grown on media with 0.0 and 5.0 mg/L GA 3 , each medium contained also 1.0 mg/L BA, while the length of shoots regenerated on the medium with 20.0 mg/L GA 3 did not differ from either [ 64 ]. The PGR content in the medium can be supposed to be the most determining factor affecting the rate of shoot growth from the isolated meristem.…”

Optimization of Agrobacterium-Mediated Transformation in Soybean

“…MS medium supplemented with 1 mg/L 6-BA, 0.1 mg/L IBA, and 2 mg/L GA 3 promoted shoot elongation significantly in Cerasus campanulata (Wang and Huang, 2002 ). In sweet potato, the combination of 10 mg/L GA 3 and 1 mg/L 6-BA could give rise to significantly taller shoots (20 mm) compared to the rest of the treatments (Masekesa et al, 2016 ).…”