Source of Explant and Light Spectrum Influence in Adventitious Shoot Regeneration of Prunus salicina Lindl. (Japanese plum)

Abstract

Light influence on shoot regeneration in Prunus salicina is a complex interaction that has been studied for the first time. Japanese plum plants were regenerated from calli and seeds of the scion cultivar 'Victoria'. The effect of four different light spectra (white, blue, red, and mixed), along with three 6-benzyladenine (BA) concentrations (1, 1.5, and 2 mg L^-1), was studied in these two sources of explants. Organogenic calli were derived from the base of stem explants of the scion cultivar 'Victoria', whereas cotyledons and embryogenic axis slices were used as seed explants. Calli cultured with 2 mg L^-1 of BA and mixed light or 2.5 mg L^-1 of BA and control light showed the highest regeneration rates, with no significant differences compared to other treatments. Seed explants exposed to 2.5 mg L^-1 of BA and red light exhibited significantly higher organogenesis. In comparison, those in 1.5 mg L^-1 of BA with blue light or 2.5 mg L^-1 of BA with mixed/control light showed no regeneration. BA concentration did not have a significant effect in the induction of somatic shoots from any explant source. In contrast, a strong interaction between light and BA was noticed. This work presents a protocol that can be applied in transformation and editing research as light spectrum studies continue to advance.

Keywords: 6-benzyladenine; LEDs; de novo regeneration; morphogenesis; somatic shoots.

Figure 1

(a) ‘Victoria’ clones in multiplication media, (b) meristematic bulk, (c) callus obtained from the bottom of a meristematic bulk, (d) regenerating calli in a Petri dish, (e) regenerating calli, (f) shoots regenerated from a callus.

Figure 2

Effect of BA concentration and light spectrum on regeneration rates of calli explants of plum cv. ‘Victoria’. Values are means ± SE. Letters indicate differences (p < 0.05) between treatments where p ≥ 0.05 means no significant (ns), p < 0.01 means very significant (**).

Figure 3

Effect of BA concentration and light spectrum on regeneration rates of seed explants of plum cv. ‘Victoria’. Values are means ± SE. Letters indicate differences (p < 0.05) between treatments where p ≥ 0.05 means no significant (ns), p < 0.05 means significant (*), p < 0.001 means very significant (***).

Figure 4

Number of shoots per type of explant in ‘Victoria’ seeds. Values are means ± SE. Letters indicate differences (p < 0.05) between treatments.

Figure 5

(a) ‘Victoria’ seed, (b) ‘Victoria’ seed deprived from seed coat, (c) seed excision: embryogenic axis and cotyledon slices, (d) seed explants in a Petri dish, (e) regenerating Cotyledon 1, (f) multiple shoots in Cotyledon 1, (g) indirect shoot regeneration from embryogenic axis.

Figure 6

Rate of indirect and indirect regeneration in seed explants per culture media. Values are means ± SE. Letters indicate differences (p < 0.05) between BA treatments and asterisk (*) denotes differences between direct and indirect organogenesis.