Effect of explant type (leaf, stem) and 2,4-D concentration on callus induction: influence of elicitor type (biotic, abiotic), elicitor concentration and elicitation time on biomass growth rate and costunolide biosynthesis in gazania (Gazania rigens) cell suspension cultures

Bioresources and Bioprocessing

Table 1 Effect of explant type and 2,4-D concentration on callus induction (%) after 4 weeks of growth

Origin of callus	2,4-D (mg/L)	Callus induction (%)
Stem	0.0	50.0 ± 5.8^b(C)
Stem	0.5	70.0 ± 0.0^ab(B)
Stem	1.0	80.0 ± 10.0^a(AB)
Stem	1.5	90.0 ± 5.8^a(A)
p values (one-way ANOVA) (stem explants, 2,4-D concentration)		0.013*
Leaf	0.0	60.0 ± 5.8^a(BC)
Leaf	0.5	70.0 ± 5.8^a(B)
Leaf	1.0	80.0 ± 5.8^a(AB)
Leaf	1.5	70.0 ± 10.0^a(B)
p values (one-way ANOVA) (leaf explants, 2,4-D concentration)		0.330 ns
p values (two-way ANOVA/general linear model)
2,4-D concentration (A)		0.006**
Explant type (B)		0.045*
(A)*(B)		0.020*

Means (n = 30) ± standard error (S.E.) with the same letter in a column are not statistically significant different from each other according to the Duncan’s multiple range test at p ≤ 0.05. ns p > 0.05; *p ≤ 0.05; **p ≤ 0.01. Superscript small letters—differences between four 2,4-D concentrations for each explant type (either stem or leaf) separately (one-way ANOVA). Superscript capital letters in parenthesis—differences between samples from the combined effect of two explant types (leaf, stem) and four 2,4-D concentrations (two-way ANOVA)