Anatomical characteristics of fusoid cells and vascular bundles in Fargesia yunnanensis leaves

As of today, the functions of fusoid cell, and the transport and loading pathways of photoassimilate in bamboo leaves are still not clear. In this paper, the leaves of Fargesia yunnanensis from a greenhouse and the wild were respectively used as samples to analyze the anatomical characteristics of fusoid cells and vascular bundles. The results showed that the bamboo leaves from greenhouse got shorter and thinner with fewer layers of palisade parenchyma cells than those from the wild. The volumes of fusoid cells were also increased. Fusoid cells originated from a huge parenchyma cell as testified by the observed nuclei. Several fusoid cells usually formed one cell complex close to the midrib. Crystals were detected in fusoid cells but no pits or plasmodesmata on their walls, suggesting that fusoid cells had the function of regulating water. The presence of fusoid cells determined the major difference between a leaf blade and sheath. There were prominent chloroplasts with simple stroma lamellae in the parenchymatous bundle sheath cells and starch grains were also observed in these chloroplast. Photoassimilates could be transported across vascular bundle sheath via symplasmic pathways for an abundant of plasmodesmata in sheath cell walls, and transported into phloem tube by apoplastic pathway as there were no pits in the walls of companion cells and phloem tubes.