Sequence of gene action can be determined from unidirectional complementary interactions between synthetically active but genetically blocked tissues. A linear sequence of gene action has been constructed for anthocyanin synthesis in maize by this approach. This technique probably can be applied to other systems and organisms that have the requisite circumstances.

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The response of groundnut cotyledons to the presence of various growth regulators in concentrations from 0.1 to 5 mg/l has been studied in detail using several genotypes of groundnut on two different media. Cotyledons with embryo axis, cultured on Blaydes' medium with cytokinins, produced shoots, in the axils of which 2-7 flower buds could be seen. The frequency of flower bud induction in general increased with increasing concentrations of cytokinins, the optimal levels being 3 mg/l of KN or 4 mg/l of BAP. Cotyledons without embryo axis, cultured on Blaydes' medium with BAP (0.5 mg/l), produced a cluster of flower buds directly, ranging in number from 8-28, without any vegetative growth. Excised embryo axes cultured on the same medium gave plantlets without flower buds. The growth regulators IAA, NAA, GA3 and ABA failed to induce flower buds in independent treatments. However, lower concentrations of IAA and NAA in combination with cytokinins exerted a positive influence on flowering. The blooming of the flower buds was facilitated on media supplemented with low concentrations of cytokinins. Six percent of the induced flowers resulted in gynophore development and ultimately formed pods when cultured under complete dark conditions in modified MS medium supplemented with kinetin.

Totipotent callus cultures were established from anther-free glumes of 'Sweet corn', 'Seed corn,' 'DHM 103' and 'DHM 101' on MS medium supplemented with 1-2 mg/l 2,4-D. The callusing response of the glumes was tested on six different media. Glumes at the uninucleate stage of pollen development callused with a high frequency compared to other stages. Organogenesis was observed in 40% of the cultures on media devoid of hormones. A total of 76 plantlets were regenerated on medium with 0.5-1.0 mg/l of both IAA and kinetin. Cytological observations in root tips indicated a diploid chromosome number (2n=20).