Plant Science, 38 (1985) 61--64 61 Elsevier Scientific Publishers Ireland Ltd. ENHANCEMENT IN THE FORMATION OF SHOOT INITIALS BY PHYTOCHROME IN STEM CALLUS CULTURES OF BRASSICA OLERACEA VAR. BOTRYTIS SUMAN BAGGA, V.K. RAJASEKHAR, SIPRA GUHA-MUKHERJEE and SUDHIR K. SOPORY* Plan t Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067 (India) (Received September 25th, 1984) (Revision received December 3rd, 1984) (Accepted December 3rd, 1984) Dark grown (20-day-old) callus obtained from explants of Brassica oleracea var. botrytis formed shoot initials 12 days after transfer to light. However, if 15-day-old dark grown callus was exposed to continuous white light the production of shoot initials was hastened as compared to dark control. Instead of the white light, if red light was given for 5 min each day for a total period of 5 days, the shoot initiation started on 3rd day and the response was higher than that found in dark grown cultures. Far-red light given for 10 min showed no effect and if it followed red light, the effect of red light was annuled. These experiments suggest that involvement of phyto- chrome in shoot initiation in this system. Key words: Brassica oleracea var. botrytis; phytochrome; shoot initials Introduction Materials and methods Light intensity and daily photoperiod have been shown to affect organogenesis in plant tissue cultures, but the information is still scanty on the involvement of specific spectral region in the morphogenetic phenomenon [ 1 ]. The presence of photomorphogenetic pigment, phytochrome has been demonstrated by a few workers in tissue cultures [2--10] and this photoreceptor has also been shown to regulate organogenesis in lettuce tissue cultures [11]. However, no morphogenetic changes have been reported in callus cultures of the Cruci- ferae, despite the demonstration of presence of phytochrome in them [9]. In the present study, we report on the involvement of phyto- chrome in initiating shoot formation in the callus obtained from stem discs of B. oleracea. *To whom correspondence should be sent. Abbreviation: Pfr, far-red absorbing form of phyto- chrome. Seeds of B. oleracea vat. botrytis were ob- tained from Indian Agricultural Research Institute, New Delhi and the seedlings were grown in the green house. When the plants attained flowering stage (80--90 days), the stem discs were excised and cultured according to Bagga et al. [12]. The culture media em- ployed was of Gamborg et al. [13], with the addition of napthaleneaceticacid (2 p.p.m.) and benzylaminopurine (0.5 p.p.m). All the cultures were kept in total darkness for 15 days at 24 + I°C. Light treatments were given as described in the text. Light sources were according to Sharma et al. [14] with modifi- cations. Red light (1.47 Wm -2) was obtained by filtering the light from four 100-W tungsten lamps through a CBS-650 filter (Carolina Bio- logical Supply Co., U.S.A. ;emission maximum, 650 nm}, and far-red light (1.50 Wm -2) from a 300-W tungsten reflector lamp (Westing- house, U.S.A., emission maximum 750 nm) and 8 cm of constantly flowing tap water. A set of 25 cultures was maintained for each 0168-9452/85/$03.30 G Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland