The Relevance of Programmed Cell Death to Spontaneous Defoliation in Sugarcane Leaf Sheaths

Spontaneous defoliation performance is of great importance for increasing the harvest efficiency and the quality of millable cane that differs between varieties. However, the details of this process are largely unknown. Herein, the number of viable cells and degree of DNA damage were investigated in the abscission zones of the sheaths of the first, third, fifth, and seventh leaves in four sugarcane varieties with different spontaneous defoliation performances. The results showed that the number of viable abscission zone cells of the fifth and seventh leaf sheaths of shedding-prone varieties was significantly lower than shedding-resistant varieties. The abscission zone DNA integrity of the seventh leaf sheath of shedding-prone varieties was significantly lower than shedding-resistant varieties. The DNA damage of the first to seventh leaf sheaths of shedding-prone varieties increased significantly with the decline of leaf position. The spontaneous defoliation rate was significantly negatively correlated with the number of viable cells in the abscission zones of the fifth and seventh leaf sheaths and positively correlated with the DNA damage in the abscission zone of the seventh leaf sheath. In conclusion, our research indicated that spontaneous sugarcane defoliation was highly related to programmed cell death that occurred differently between varieties.

Automated summary

This study investigated sugarcane varieties with different spontaneous defoliation performances and found that shedding-prone varieties have fewer viable cells in the abscission zone and lower DNA integrity in the seventh leaf sheaths. Furthermore, the spontaneous defoliation rate is correlated with the number of viable cells and DNA damage.