caa a22 4500 477100945 CHVBK 20180405111541.0 cr unu---uuuuu 170330e19960401xx s 000 0 eng 10.1007/BF00262644 doi (NATIONALLICENCE)springer-10.1007/BF00262644 Distribution and frequency of plasmodesmata in relation to photoassimilate pathways and phloem loading in the barley leaf [Elektronische Daten] [Ray Evert, William Russin, C. Botha] Large, intermediate, and small bundles and contiguous tissues of the leaf blade of Hordeum tvulgare L. ‘Morex' were examined with the transmission electron microscope to determine their cellular composition and the distribution and frequency of the plasmodesmata between the various cell combinations. Plasmodesmata are abundant at the mesophyll/parenchymatous bundle sheath, parenchymatous bundle sheath/mestome sheath, and mestome sheath/vascular parenchyma cell interfaces. Within the bundles, plasmodesmata are also abundant between vascular parenchyma cells, which occupy most of the interface between the sieve tube-companion cell complexes and the mestome sheath. Other vascular parenchyma cells commonly separate the thick-walled sieve tubes from the sieve tube-companion cell complexes. Plasmodesmatal frequencies between all remaining cell combinations of the vascular tissues are very low, even between the thin-walled sieve tubes and their associated companion cells. Both the sieve tube-companion cell complexes and the thick-walled sieve tubes, which lack companion cells, are virtually isolated symplastically from the rest of the leaf. Data on plamodesmatal frequency between protophloem sieve tubes and other cell types in intermediate and large bundles indicate that they (and their associated companion cells, when present) are also isolated symplastically from the rest of the leaf. Collectively, these data indicate that both phloem loading and unloading in the barley leaf involve apoplastic mechanisms. Springer-Verlag, 1996 Hordeum nationallicence Leaf nationallicence Phloem loading and unloading nationallicence Plasmodesmatal frequency nationallicence Sieve tube nationallicence Evert Ray Departments of Botany and Plant Pathology, University of Wisconsin, 430 Lincoln Drive, 53706-1381, Madison, WI, USA aut Russin William Department of Botany, University of Wisconsin, 430 Lincoln Drive, 53706-1381, Madison, WI, USA aut Botha C. Department of Botany, University of Wisconsin, 430 Lincoln Drive, 53706-1381, Madison, WI, USA aut Planta Springer-Verlag 198/4(1996-04-01), 572-579 0032-0935 198:4<572 1996 198 425 https://doi.org/10.1007/BF00262644 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00262644 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Evert Ray Departments of Botany and Plant Pathology, University of Wisconsin, 430 Lincoln Drive, 53706-1381, Madison, WI, USA aut NATIONALLICENCE 700 1- Russin William Department of Botany, University of Wisconsin, 430 Lincoln Drive, 53706-1381, Madison, WI, USA aut NATIONALLICENCE 700 1- Botha C. Department of Botany, University of Wisconsin, 430 Lincoln Drive, 53706-1381, Madison, WI, USA aut NATIONALLICENCE 773 0- Planta Springer-Verlag 198/4(1996-04-01), 572-579 0032-0935 198:4<572 1996 198 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer