Preservation of the Tonoplast in Metaphloem Sieve Elements of Embryonic Roots of Zea mays L.

Publisher Website
Google Scholar
Abstract
Decortication of embryonic roots of 4- to 5-day-old Zea seedlings and subsequent chemical fixation permitted comparison of cut and uncut developing sieve elements In a decorticated root where sieve tubes are not severed, metaphloem sieve elements in late states of development and some mature sieve elements exhibit a highly vacuolate condition When roots are cut or diced in the course of fixation intact vacuoles are not observed in late stages of sieve-element ontogeny The degree of callose formation at sites of developing sieve-plate pores and in the pores of mature sieve elements varies greatly with both decortication and non-decortication treatments Nuclei were not observed in sieve elements at the electron microscope level, but they were seen at the light microscope level in serial sections of sieve elements in the late to mature developmental stages represented Although the occurrence and distribution of plastids, mitochondria, endoplasmic reticulum, dictyosomes and nbosomes also vanes in sieve elements of decorticated roots, disruption or surging of sieve-element contents is greater for sieve tubes that are severed during fixation treatment A discussion is presented relating effects of trauma on observed developmental stages and sieve-element structure