| Abstrakt: |
Tissue cultures of Zea mays L. derived from four different somatic sources all appeared to grow as callus. Microscopic examination, however, showed this growth to be merely an aberrant root‐like form. A continium in the degree of aberrant root behavior, ranging from cultures appearing very root‐like to those visibly indistinguishable from callus, was recognized. The continuum and ultimately the callus appearance resulted from increasing inhibition of root elongation coupled with strong enhancement of branch root initiation. This aberrant form of root growth was apparent in all cultures observed. Tissue source and growth regulator treatment interacted to shift the growth form within the extremes of the continuum but in no case was the root‐like mechanism of proliferation disrupted, even during extended subculture. Removal of exogenous growth regulators from the culture medium simply allowed outgrowth of existing root primordia as normal roots and this accounts for the characteristic ease of rhizogenesis from what has been called maize callus. [ABSTRACT FROM AUTHOR] |
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