The slender phenotype of pea: stem growth, peroxidase levels and ethylene responses

Stem elongation growth in a slender line of Pisum sativum L. was much greater than in its two dwarf parental lines due to a greater rate of production of longer internodes. The cellular basis of the greater length of slender internodes was tissue specific. In the epidermis, greater cell length primarily accounted for the longer internodes of the slender plants, but in the outer cortex, greater cell number was the more important factor. The soluble and salt-extractable peroxidase (EC 1.11.1.7) activities of expanding internodes were much lower in slender plants than in dwarf plants. The proportional effects of ethylene treatment on epicotyl length, diameter and orientation were similar in etiolated slender and dwarf seedlings.