effect of auxin -cytokinin balance and explant on callus growth and regeneration in sunflower

Abstract: Various combinations of hormones were used for culturing different explants (immature embryo, hypocotyl, cotyledon and leaf) of two sunflower genotypes (viz. cv. Miak and a synthetic population). The data showed that the highest growth rate across three growth passages of callus derived from immature embryos of cv. Miak (13.4 mg/day). This callus was obtained on MS medium supplemented with 0.5 mg L-1 Naphthaline acetic acid (NAA) and 1.0 mg L- 1 Benzylamino purine (BAP) followed by MS medium supplemented with 2.0 mg L-1 NAA and 0.1 mg L-1 BAP (12.0 mg/day). In general, average growth rate was highest at the 1st passage (12.5 mg/day), then it was reduced to 6.1mg/day at the 2nd one, and to 2.5 mg/day at the third one. For regeneration percentage from the same calli, using MS medium containing 0.1 mg L-1 NAA and 2.0 mg L-1 BAP was the best (70.5%) followed by MS medium supplemented with 2.0 mg L-1 NAA and 0.1 mg L-1 BAP (54%). Either the absence of auxin or cytokinin or the high concentrations of both of them caused loss of regeneration ability. However, regeneration was favored by combinations of low NAA with high BAP or by high NAA with low BAP. It seems that there is no relation between callus growth rate and regeneration ability.
Using the MS medium supplemented with 2.0 mg L-1 NAA and 0.1 mg L-1 6-BAP showed superiority over the other tested media for giving the highest growth rate of callus derived from cotyledons and leaves of cv. Miak and the synthetic population. Generally, growth rate of callus derived from cotyledons of the Syn. Pop was lesser than that of Miak, however, no regeneration was observed in the Syn. Pop using cotyledon explant. For hypocotyl explant, MS medium with 0.1 mg L-1 NAA and 2.0 mg L-1 BAP gave the highest callus growth rate for both genotypes and average callus growth rate was gradually increased from the 1st through the 3rd passage for both genotypes.
In general, hypocotyl was the best explant for obtaining high regeneration response as compared to cotyledon and leaf explants. Only MS medium supplemented with 0.5 mg L-1 of both NAA and 6-BAP was able to regenerate plants from cotyledons of Miak. Regeneration percentage was the highest from Miak hypocotyls, when using MS medium supplemented with 0.5 mg L-1 NAA and 1.0 mg L-1 BAP, followed by MS medium supplemented with 0.5 mg L-1 NAA and 0.5 mg L-1 BAP. While, the Syn. Pop showed high regeneration by using MS medium containing 0.1 mg L-1 NAA and 0.5 mg L-1 BAP, followed by MS medium containing 0.1 mg L-1 NAA and 2.0 mg L-1 BAP. It could be concluded that the most efficient hormone concentration for regeneration in sunflower depends on genotype and type of explant.
Publication year 2003
Pages 213-228
Availability location معهد بحوث المحاصيل الحقلية- 9 ش الجامعة – الجيزة
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External authors (outside ARC)
    إبراهيم محمد عامر قسم البحوث النباتية – مركز البحوث النووية .
    عادل حب الله قسم المحاصيل – كلية الزراعة – جامعة القاهرة.
    رضا شبانة قسم المحاصيل – كلية الزراعة – جامعة القاهرة.
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AGROVOC
TERMS
Auxins. Cytokinins. Helianthus annuus.
Proposed Agrovoc