Tyloses in the Lopingian cordaitalean root from Xinjiang, Northwest China

Tyloses occur in the conductive tissues of both extant and fossil plants. They contribute to limit the spread of pathogens and other wood decay organisms. A novel well-preserved cordaitalean root, Amyelon turpanense nov. sp., was discovered in the Lopingian deposits of Wutonggou Formation in the Turpan Basin, Xinjiang Uygur Autonomous Region, Northwest China. The permineralized root is characterized by the diarch protostele, exarch primary xylem and Protophyllocladoxylon-type secondary xylem. A large number of highly developed tyloses were found in the secondary xylem of Amyelon turpanense. It is the first time to discover the tylosis formation in the cordaitalean root. A lot of fungal remains are discovered in the secondary xylem of the root. The tyloses and resinous materials may play a role in slowing down and preventing further infection of the pathogenic fungi.