Effects of Boron on Growth and Lignification in Sunflower Tissue and Organ Cultures

The influence of boron on the growth of and lignin formation in stem callus and root cultures of sunflower, Helianthus annuus L., was investigated. A significantly lower rate of growth in both types of tissue was observed to result from a deficiency of boron in the nutrient medium. This effect was noted during the third 30-day transfer period with callus cultures, while it appeared in the second 10-day transfer period with roots. Boron deficiency resulted in a lower degree of lignification of both callus and roots. The total lignin content of boron-deficient tissues was significantly less than that of those receiving adequate boron. Although boron deficiency resulted in changes in catalase activity in the tissues, the trends were not consistent. The peroxidase activity of boron-deficient tissues was consistently and significantly lower than that of tissues receiving boron in the nutrient medium. It is proposed that the lower peroxidase activity may account in part for the lower degree of lignification of ...