Corn Starch As An Alternative Gelling Agent For plAnt Tissue Culture

Plant Cell, Tissue and Organ Culturel5: 17-22(1988) © Kluwer Academic Publishers, Dordrecht - Printed in the Netherlands

Corn starch as an alternative gelling agent for plant tissue culture
W.E. H E N D E R S O N 1 & A.M. K I N N E R S L E Y 2
c P c International, Moffett Technical Center, Box 345, Summit-Argo, IL 60501, USA; (1present address: Enzyme Biosystems, 3350 Salt Creek Lane, Suite103, Arlington Heights, IL 60005, USA; 2present address: Phyton Technologies Inc. Science and Technology Center, 1299 Bethel Valley Road, Oak Ridge, TN 37830, USA)

Received 16 October 1987; accepted in revised form 1 March 1988
Key words: agar, corn starch, carrot cell cultures, tobacco cell cultures, anthocyanin,

cell growth
Abstract. Growth and differentiation of plant cell cultures wasincreased when media were

gelled with corn starch instead of agar. Dry weight of tobacco and wild carrot cell cultures on media gelled with starch was more than three times that of cultures on media gelled with agar. Higher yield of anthocyanin and dry weight of embryos were found in wild carrot cultures grown on media gelled with corn starch. The starch-mediated increase in growth anddifferentiation of wild carrot ceils was accompanied by an increase in density of the cultures shown by higher dry weight/fresh weight ratios.

Introduction

Agar is the most frequently used gelling agent for plant tissue culture media. It has desirable characteristics o f high gel clarity, stability, and resistance to metabolism during use. Agar has been considered biologically inert, although thisbelief has increasingly been questioned [1, 2, 3]. In anther culture o f Nicotiana tabacum, inhibitory effects o f agar, resulting in e m b r y o abortion, have been reported [4]. Sorvari [5, 6, 7] has investigated starches from barley, corn, potato, rice and wheat as alternative gelling agents to agar. E m b r y o formation from barley anthers was greater on media gelled with starch than onagar-solidifled media. O f the starches examined, barley was the most effective. Frequency o f plantlet p r o d u c t i o n f r o m anthers cultured on media with barley starch was five times higher than from anthers on agar-solidified media. Subsequently Sorvari showed that shoot differentiation from p o t a t o tuber discs was obtained within three weeks after inoculation on media gelled with barleystarch. In contrast, other investigations have found that 5-14 weeks o f culture was necessary for p o t a t o shoot f o r m a t i o n on agar media.

18 In our studies, cell cultures of tobacco and wild carrot have been grown on media gelled with agar and corn starch to determine if Sorvari's observations could be confirmed and whether secondary product formation was improved on starch-gelledmedia.

Materials and methods

Cultures The origin of cultures of wild carrot (Daucus carota L.), cell line WC 63-2, and the culture media used to study anthocyanin accumulation and embryogenesis has been described by Kinnersly & Henderson [8]. The same reference describes the origin and culture conditions for suspension cultures of Nicotiana tabacum cv. Burley 21. Starch Corn starch, CornProducts Code 3005, was used in the studies with tobacco cell cultures. This starch is essentially food-grade corn starch available at most supermarkets. A 60 fluidity acid-modified corn starch, Code 5061, was derived from the same material, but with a reduced molecular weight. This was prepared by treating 162 g of 3005 starch in an equal volume of water with 4.5 m112 N HC1 for 6-8 h at 128 °F. Themixture was then neutralized with N a O H to a final pH of 4.4-4.6, filtered through # 1 Buchner funnel, and air-dried. This starch was used in the experiments with wild carrot cell cultures. Corn syrup Globe ® 1632 corn syrup was obtained from CPC International, Englewood Cliffs, New Jersey. A description of tlais syrup is provided in ref. [8]. Preparation of culture media Difco Bacto-agar...