J. Pozueta-romero et al., Enhanced regeneration of tomato and pepper seedling explants for Agrobacterium-mediated transformation, PL CELL TIS, 67(2), 2001, pp. 173-180
Seedling explants of three tomato ( Lycopersicon esculentum) and four bell
pepper (Capsicum annuum) cultivars consisting of the radicle, the hypocotyl
and one cotyledon were obtained after removing the primary and axillary me
ristems. After 14 days of incubation on solid Murashige and Skoog (MS) medi
um without growth regulators, explants of both species regenerated multiple
shoots on the cut surface (2.9-5.3 shoots per explant for tomato and 1.2-2
.2 for bell pepper cultivars). After excision, the shoots were rooted on so
lid MS medium and acclimated to the greenhouse. This method was highly effi
cient in tomato and, particularly, in bell pepper, where plant regeneration
is especially difficult. We used these explants to transform tomato with A
grobacterium tumefaciens containing a 35S-GUS-intron binary vector. As show
n by GUS expression, 47% of the tomato explants produced transformed merist
ems, which differentiated into plants that exhibited a low (3%) tetraploidy
ratio. Southern blots and analysis of inheritance of the foreign genes ind
icated that T-DNA was stably integrated into the plant genome. The use of t
his technique opens new prospects for plant transformation in other dicotyl
edoneous plants in which genetic engineering has been limited, to date, due
to the difficulties in developing an efficient in vitro regeneration syste
m.