| Abstrakt: |
Grafting technology is applied to control the trunk canker disease of Chinese hickory (Carya cathayensis). In this study, the grafting of Chinese hickory hybrids onto American pecan (C. illinoinensis) and Hunan pecan (C. hunanensis) as rootstocks was investigated in the field. The trunk canker was significantly more serious in self-grafted C. cathayensis(CC), and the disease of C. hunanensis-grafted C. cathayensis(HC) was less serious than that of C. illinoinensis-grafted C. cathayensis(IC). The causal agent of Botryosphaeria dothideawas characterized by comparison of the fungal morphology and its combined DNA sequence data. Seedlings of CC, IC and HC were inoculated with B. dothidea, and we observed that the phloem and xylem tissues of CC were more damaged by B. dothideamycelia than those in IC and HC at 2 and 4 days, respectively, using a scanning electron microscope (SEM). The phenol contents in the trunk bark tissues of HC, the total phenylalanine ammonia-lyase (PAL) activities of HC and IC were significantly increased, and the total polyphenol oxidase (PPO) activity of HC was higher than that of other pecans at 5 days. The expression levels of the CHSgene were significantly upregulated in HC, and the expression levels of PAL, C4H, 4CL, and CHSin IC and HC were high at 1, 3, and 5 days. In summary, the grafted pecan IC and HC showed higher phenol content, PAL activity, and C4H, CHS, and PALgene expression levels. This study explains the potential of using C. hunanensisas a rootstock to control the Botryosphaeria canker disease in C. cathayensis. |
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