Cork Development: What Lies Within

Abstract

The cork layer present in all dicotyledonous plant species with radial growth is the result of the phellogen activity, a secondary meristem that produces phellem (cork) to the outside and phelloderm inwards. These three different tissues form the periderm, an efficient protective tissue working as a barrier against external factors such as environmental aggressions and pathogen attacks. The protective function offered by cork cells is mainly due to the abundance of suberin in their cell walls. Chemically, suberin is a complex aliphatic network of long chain fatty acids and alcohols with glycerol together with aromatic units. In most woody species growing in temperate climates, the first periderm is replaced by a new functional periderm upon a few years after being formed. One exception to this bark development can be found in cork oak (Quercus suber) which display a single periderm that grows continuously. Quercus suber stands by its thick cork layer development with continuous seasonal growth. Cork raw material has been exploited by man for centuries, especially in Portugal and Spain. Nowadays, its applications have widened vastly, from the most known product, stoppers, to purses or insulating materials used in so many industries, such as construction and car production. Research on how cork develops, and the effect environmental factors on cork oak trees is extremely important to maintain production of good-quality cork, and, by maintaining cork oak stands wealthy, we are preserving a very important ecosystem both by its biodiversity and its vital social and economic role in areas already showing a population declination.

The Mechanism of Ochratoxin Contamination of Artificially Inoculated Licorice Roots

“…Taken together, these results suggest that the former represent the main areas attacked by the fungus and they were highly contaminated with OTs. Meanwhile, the structure and high lignin content of the cork layer of licorice root was not easily penetrated by fungal mycelia [ 34 ]. However, LM and SEM images did show that fungal mycelia had almost completely penetrated the root after 10 days of incubation.…”

Drought impact on phellem development: identification of novel gene regulators and evidence of photosynthetic activity

“…Controlled irrigation or fertigation in cork oak stands has been proposed as a viable solution to improve cork oak development and decrease to half the time of first harvest (Vessella et al, 2010;Camilo-Alves et al, 2020, 2022. This time is usually determined by tree stem circumference at breast height (>70cm), which under natural (and optimal) conditions usually occurs after 20 years' age or more (Pereira, 2007).…”

“…Cork is a natural and fully renewable forest product obtained from the bark of Quercus suber (cork oak), with high commercial interest given its unique physical and chemical properties (Pereira, 2007; Teixeira, 2022). Cork culture also plays an important ecological role by promoting the maintenance of the traditional farming landscapes (Pereira, 2007) and contributing to carbon sequestration in these regions (Costa-e-Silva et al ., 2021).…”

Quercus suber L. Genetic Resources: Variability and Strategies for Its Conservation

“…The development of cork is an exceptional characteristic of Q. suber trees. The first cork harvest begins when the trees are about 25 years old and each harvest cycle takes approximately 10 years [5,20]. The cork resulting from the first harvesting is called virgin cork and is very irregular, while that originating from the following harvestings is called reproduction cork [5].…”