Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 94

CHERIMOYA

Juvenile phase. Jordan (1988) inoculated A. cherimola ‘Concha Lisa’ hypocotyl sections, 0.3–0.4 cm long, into liquid MS medium supplemented with 2.2 μM BA, 2.7 μM NAA and 100 μM polyvinylpyrrolidone (PVP) and in liquid Nitsch medium (Nitsch and Nitsch, 1969) supplemented with 0.4 μM BA and 0.4 μM NAA. Adventitious buds developed from all of the explants but no roots could be induced, while longer hypocotyl segments, 3–4 cm long, rooted efficiently. Encina et al. (1999b), working with long hypocotyls obtained from aseptically germinated seeds of cherimoya ‘Fino de Jete’, reported similar results. However, Jordan’s protocol for shoot regeneration from 0.3 cm-long hypocotyl sections seems to be genotype-dependent and did not work for ‘Fino de Jete’ juvenile explants. Therefore, a new protocol that has produced good results was established (Padilla and Encina, 2005) (Fig. 3.1.3b). Jordan et al. (1991), working with cherimoya zygotic embryos as primary explants, also reported regeneration. Direct shoot formation from embryonic tissues and from embryo-derived calluses was obtained on Nitsch medium containing 0.5 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and either 4.6 μM zeatin or 4.4 μM BA. For shoot regeneration, callus was transferred to Nitsch medium supplemented with 0.3 μM indoleacetic acid (IAA) and 0.02% casein hydrolysate.

Adventitious shoot development from leaf and internodal explants of juvenile cherimoya seedlings (‘Fino de Jete’) has also been obtained (Encina et al., unpublished results). Bud clusters from juvenile explants developed and rooted easily. Organogenesis occurred directly from internodal explants. Lionakis and Nzuzi Gianze (2000) reported regeneration of shoot buds from single nodal segment explants from cherimoya seedlings on half-strength MS medium supplemented with 3.5% sucrose and 4.4–88.8 μM BA and confirmed the adventitious origin of buds in anatomical studies.

Mature phase. Jordan et al. (1991) induced adventitious shoots from internodal sections of 3-year-old mature phase trees of ‘Concha Lisa’ on semi-solid Nitsch basal medium (Nitsch and Nitsch, 1969) supplemented with 2.7 μM NAA, 8.9 μM BA, 0.1% (w/v) PVP-360 and 0.02% casein hydrolysate. Antioxidants and sorbitol improved organogenesis. Adventitious shoot development from leaf and internodal explants of adult ‘Fino de Jete’ has also been obtained (Padilla and Encina, unpublished results); shoot induction from adult phase explants required an elongation treatment to develop shoots. Little or no callus was implicated in organogenesis from internodal explants, while shoot regeneration from callus can be induced from mature leaves (Encina et al., unpublished results).

SUGAR APPLE. Lemos and Blake (1996a) induced multiple shoot buds from 1.5 mm hypocotyl segments of sugar apple on WPM containing 18 μM BA. After pretreatment of shoots for 2 weeks on WPM with 10 g/l activated charcoal, rooting and acclimatization frequencies of 47% and 80%, respectively, were achieved. Nair et al. (1984b) regenerated sugar apple adventitious buds and shoots from leaf explants. The regeneration protocol included MS basal medium supplemented with 2.3 μM kinetin and 8.9 μM BA and resulted in 15.6 shoot buds from each explant. Explant type was critical, since different shoot induction frequencies were obtained from various regions of the leaves. The most responsive area consists of the leaf base with petiole (15.6 shoots), and the least responsive area is the apical leaf region with midrib, from which there was no shoot bud induction. Supplementing standard regeneration medium with different auxins promoted callus growth and fewer shoot buds. The efficiency of rooting of regenerated shoots and the recovery of complete plantlets after acclimatization was very low (10%).

SOURSOP

Juvenile phase. High-frequency adventitious shoot induction was reported from hypocotyl segments (1 cm length) from aseptically germinated seeds of A. muricata on semi-solid MS medium supplemented with 8.9 μM BA and 0.5 μM NAA (Bejoy and Hariharan, 1992). Rooting (88%) was induced on semi-solid MS medium with 9.8 μM IBA and plants have been acclimatized (60%). Lemos and Blake (1996b) induced adventitious shoots from hypocotyl explants on semi-solid WPM containing 2.7 μM NAA and 8.9 μM BA. Following shoot preconditioning treatment on WPM with 3% activated charcoal for 2 weeks, 100% rooting was observed after 15 days incubation in darkness in liquid WPM with 21.5 μM NAA and 1% galactose. Eighty per cent of the plantlets were successfully acclimatized.

Mature phase. Adventitious shoot regeneration was reported from 67% of internodal explants of mature phase soursop on semi-solid Nitsch medium supplemented with 8.9 μM BA, 2.7 μM NAA, 0.1% PVP, 0.02% casein hydrolysate and 2% sorbitol (Lemos and Baker, 1998).

ATEMOYA

Juvenile phase. Rasai et al. (1994) induced adventitious shoot formation (12.6 per explant) from hypocotyl segments of ‘African Pride’ on semi-solid MS medium containing 8.9 μM BA, 2.3 μM kinetin, 0.4 μM biotin and 0.4 μM calcium pantothenate.

Mature phase. Rasai et al. (1994) also reported induction of adventitious shoots (19 shoots from each explant) from nodal explants of mature trees (‘African Pride’) on the same medium. Approximately 40% rooting of shoots from mature phase trees was obtained following a two-step rooting method: (i) root induction in liquid MS medium containing 250–500 μM IBA for 3 days in darkness, followed by 13 days constant illumination; and (ii) root elongation on semi-solid half-strength MS medium with 0.25% (w/v) activated charcoal. A 70% survival rate was obtained after acclimatization in the glasshouse.