Anthocyanin accumulation in the hypocotyl and petal of Red Agati (Sesbania grandiflora), an ornamental legume

Seeds of Red Agati (Sesbania grandiflora), an ornamental leguminous tree, were germinated in vitro under both light and dark conditions for 7, 10, 15, 20 and 25 days. The localization of anthocyanin-containing cells and level of total anthocyanin content of hypocotyl from several developmental stages were determined. In the hypocotyl of light-grown seedlings, anthocyanin-containing cells were observed in epidermal and sub-epidermal layer and peripheral cortex while none was found in that of dark-grown seedlings. On day 7, the hypocotyl of light-grown seedlings had the highest anthocyanin content (290 μg/g FW). Moreover, Red Agati's petal at various developmental stages was also examined for the total anthocyanin content. It was found that the petal of 3 cm length had the highest total anthocyanin level (455 μg/g FW). It is concluded that the hypocotyl of light-grown Red Agati seedlings is an attractive alternative source of anthocyanins to the petal as the seedlings can be raised and be made available throughout the year. metabolite, especially anthocyanin production (Rao and Ravishankar, 2002; Filippini et al., 2003). Though there were some publications on tissue culture of Sesbania, the objective of most of them was to propagate this plant (Shanker and Ram, 1990; Shanker and Ram, 1993; Sinha and Mallick, 1993; Detrez et al., 1994). Unlike Agati, Red Agati has a remarkably red petal that would be a good source of anthocyanin. However, the hypocotyl of a Red Agati seedling is also red. This could be a more attractive and convenient source for anthocyanin production than petal. With this goal in mind, the present study was undertaken to compare the amount of anthocyanin extracted from the hypocotyl and petal of Red Agati and investigate the time during their development when maximal accumulation of anthocyanin might occur in the appropriate organ. Materials and methods Plant materials: Mature dry seeds of Red Agati were obtained from a local garden of Nonthaburi province. To avoid possible complications from microbial contamination during raising seedlings from seeds for the present experiments, the Red Agati seeds were germinated under aseptic conditions: they were immersed in sterile distilled water overnight before they were surface-sterilized by soaking in 70% (v/v) ethanol for 30 seconds, 1.5% (v/v) sodium hypochlorite for 15 minutes and rinsing them three times with sterile distilled water. After seeds germinated in vitro on the medium (see Medium) under both light and dark conditions for 7, 10, 15, 20 and 25 days, hypocotyl from these seedlings were cut and examined for total anthocyanin content