Correlation analysis between continuous cropping obstacle of Gastrodia elata and Ilyonectria fungi and relieving strategy / 中国中药杂志

The continuous cropping obstacle of Gastrodia elata is outstanding, but its mechanism is still unclear. In this study, microbial changes in soils after G. elata planting were investigated to explore the mechanism correlated with continuous cropping obstacle. The changes of species and abundance of fungi and bacteria in soils planted with G. elata after 1, 2, and 3 years were compared. The pathogenic fungi that might cause continuous cropping diseases of G. elata were isolated. Finally, the prevention and control measures of soil-borne fungal diseases of G. elata were investigated with the rotation planting pattern of "G. elata-Phallus impudicus". The results showed that G. elata planting resulted in the decrease in bacterial and fungal community stability and the increase in harmful fungus species and abundance in soils. This change was most obvious in the second year after G. elata planting, and the soil microbial community structure could not return to the normal level even if it was left idle for another two years. After G. elata planting in soils, the most significant change was observed in Ilyonectria cyclaminicola. The richness of the Ilyonectria fungus in soils was significantly positively correlated with the incidence of G. elata diseases. When I. cyclaminicola was inoculated in the sterile soil, the rot rate of G. elata was also significantly increased. After planting one crop of G. elata and one to three crops of P. impudicus, the fungus community structure in soils gradually recovered, and the abundance of I. cyclaminicola decreased year by year. Furthermore, the disease rate of G. elata decreased. The results showed that the cultivation of G. elata made the Ilyonectria fungi the dominant flora in soils, and I. cyclaminicola served as the main pathogen of continuous cropping diseases of G. elata, which could be reduced by rotation planting with P. impudicus.

Resistance of different ecotypes of Gastrodia elata to tuber rot / 中国中药杂志

Tuber rot has become a serious problem in the large-scale cultivation of Gastrodia elata. In this study, we compared the resistance of different ecotypes of G. elata to tuber rot by field experiments on the basis of the investigation of G. elata diseases. The histological observation and transcriptome analysis were conducted to reveal the resistance differences and the underlying mechanisms among different ecotypes. In the field, G. elata f. glauca had the highest incidence of tuber rot, followed by G. elata f. viridis, and G. elata f. elata and G. elata f. glauca×G. elata f. elata showed the lowest incidence. Tuber rot showcased obvious plant source specificity and mainly occurred in the buds and bottom of G. elata plants. After infection, the pathogen spread hyphae in host cortex cells, which can change the endophytic fungal community structure in the cortex and parenchyma of G. elata. G. elata f. glauca had thinner lytic layer and more sugar lumps in the parenchyma than G. elata f. elata. The transcription of genes involved in immune defense, enzyme synthesis, polysaccharide synthesis, carbohydrate transport and metabolism, hydroxylase activity, and aromatic compound synthesis had significant differences between G. elata f. glauca and G. elata f. elata. These findings suggested that the differences in resis-tance to tuber rot among different ecotypes of G. elata may be related to the varied gene expression patterns and secondary metabolites. This study provides basic data for the prevention and control of tuber rot and the improvement of planting technology for G. elata.