Structural Changes in Primary Lenticels of olea Europaea and Cercis Siliquastrum During The Year

Abstract

The structure of primary lenticels of the Mediterranean evergreen Olea europaea and the winter deciduous species Cercis siliquastrum was investigated during the year using scanning electron, conventional brightfield and epi-fluorescence microscopy. It was revealed that lenticels of O. europaea do not undergo significant structural changes over this time period. The filling tissue of O. europaea lenticels consists of fully-suberized cells that form small intercellular spaces. The air-exposed filling cells are replaced during spring and early summer by new early-suberized cells. Further notable structural modifications during the year were not observed. By contrast, lentice1s of C. siliquastrum possess a closing layer of suberized cells delimiting an underlying mass of non-suberized filling cells. During the period of high metabolie activity of the plant, i.e. during spring and early summer, the suberized closing layer is ruptured from the pressure exerted by the newly formed underlying cells. During late summer a new closing layer is formed, delimiting again the non-suberized underlying filling cells during winter. The possible role of lenticels in the gas exchange process is discussed. In both species the shade-adapted parenchyma cells of the cortex beneath lenticels shows bright red auto-fluorescence of chlorophyll, a phenomenon that is not yet fully understood.

Chloroplast Distribution in the Stems of 23 Eucalypt Species

“…Lenticels permit gas exchange through the otherwise impervious periderm. For Olea europaea and Cercis siliquastrum, the parenchyma cells beneath the lenticels showed a brighter red auto-fluorescence than those elsewhere [ 64 ], similar to that described for stomata in the young eucalypt branchlets. It has also been suggested that lenticels may also permit more light into the stem than the general periderm but this was not substantiated in a study of 10 species that examined one-year-old twigs [ 65 ].…”

Controls on methane emissions from Alnus glutinosa saplings

“…Lenticel presence, number, type, degree of opening, development stage and area vary between tree species (Langenfeld‐Heyser, ; Kalachanis & Psaras, ). Moreover, the development stage of a tree species (Lendzian, ; Kalachanis & Psaras, ), which commonly is affected by external factors and environmental conditions, also impacts the formation of lenticels (Kuo‐Huang & Hung, ). Any change in stem lenticel density may influence development of stem and root aerenchyma tissues, and thus potentially alter rates of CH 4 transport.…”

“…While our study demonstrates a strong positive relationship between stem lenticel density and tree‐mediated CH 4 emissions in A. glutinosa , further work is required to determine whether such a relationship is common in other tree species. Lenticel presence, number, type, degree of opening, development stage and area vary between tree species (Langenfeld‐Heyser, ; Kalachanis & Psaras, ). Moreover, the development stage of a tree species (Lendzian, ; Kalachanis & Psaras, ), which commonly is affected by external factors and environmental conditions, also impacts the formation of lenticels (Kuo‐Huang & Hung, ).…”

Comparison of good- and bad-quality cork: application of high-throughput sequencing of phellogenic tissue

“…We looked for orthologues of genes that are involved in stomatal development because it is believed that stomata are the founder structures for lenticular channels (Kalachanis and Psaras, 2007). We screened the Q. suber phellogen transcriptome database using the Arabidopsis bHLH transcription factors encoded by the FAMA, SPEECHLESS, and MUTE genes; and Arabidopsis homeodomain-leucine zipper IV proteins encoded by MERISTEM LAYER 1 (ML1) and HOMEODOMAIN GLABROUS2 (HDG2) genes.…”