Analysis of leaf tissue structures between rust-resistant and rust-susceptible Zoysia grass (Zoysia japonica)

Abstract

The differences of leaf anatomic structures between rust-susceptible and -resistant zoysia (Zoysia japonica) were compared to reveal the physical defense mechanism of rust-resistant zoysia against Puccinia zoysiae. Zoysias were screened in greenhouse and fields of Beijing, Qingdao and Yangzhou from 2009 to 2012. After identified by inoculation test, rust-susceptible and rust-resistant zoysias were transplanted to flowerpots in Shangzhuang test field (Beijing, China) and were divided into indoor and outdoor groups. Leaves in the same position and formed in the same growth period of both rust-susceptible and rust-resistant zoysia strains were chosen for the current study. Wax content, the number and size of stomata, and the thickness of palisade tissue, spongy tissue, upper epidermis and lower epidermis were analyzed. All the anatomic structures of leaves stained with toluidine blue were observed under microscope. Leaf epidermis wax contents of rust-susceptible zoysia in indoor and outdoor groups were 30 and 39% lower than that of rust-resistant zoysia (p < 0.05), respectively. The number of stomata in rust-resistant zoysia was 68% more than that in susceptible ones (p < 0.05). Stomata of rust-resistant zoysia were 45% shorter and 65% narrower than those of rust-susceptible zoysia (p < 0.05). The thickness of spongy parenchyma and palisade tissue in rust-resistant zoysia was significantly higher than that of the susceptible samples (p < 0.05). Cell structure tightness and cell structure looseness of rust-resistant zoysia were tighter than that of rust-susceptible zoysia. Our study provides a histological understanding of the resistance mechanism of rust-resistant zoysia and might be useful for the identification of resistant varieties.