Identification and inhibiting effect of pathogens that caused tuber rot of Bletilla striata

Abstract

In order to identify the pathogens that caused tuber rot in Bletilla striata and study the inhibiting effects of herbal extracts on pathogens, the pathogens that caused tuber rot of B. striata were isolated using usual tissue isolation the strains were identified by morphological and molecular biological techniques, and inhibiting effects of seven traditional Chinese medicine extracts on pathogen were observed. The results were as follows:(1) A total of fourteen fungi and four bacteria were isolated from diseased leaves, leaf sheaths and tubers. But only strain GF-1 caused disease, whose symptoms consistent with those in the field. The incidences of GF-1 disease reinoculated in the field and laboratory were both 100％. (2) GF-1 was identified as a member of Epicoccum, and its colonial morphology was a circular form, with white mycelium, prostrate on the medium, aerial, diaphragms and branches. There were conidia and chlamydospores. (3) At last, the sequence of internal transcribed spacer (ITS) region of GF-1 were analyzed, the length was 522 bp. The sequence was compared with other species in the GenBank and reached 99.62% similarity to Epicoccum sorghinum (MN493119.1) isolated form Sorghum, which was closer than others, including Epicoccum sorghinum (MF948994.1) isolated form leaves of Bletilla striata. (4) GF-1 could be fully inhibited when the medium contained 0.1-0.2 g·mL-1 extracts that extracted from seven traditional Chinese medicines, respectively. It also could be fully inhibited by 0.05 g·mL-1 of Cinnamomum cassia or Syringa oblate. In summary, the pathogen that caused tuber rot in Bletilla striata was identified as Epicoccum sorghinum. And GF-1 could be fully inhibited cultivated on the medium which contained 0.1-0.2 g·mL-1 herbal extracts, e.g.: Cinnamomum cassia, Syringa oblate, Cyclocarya paliurus, Bletilla striata, Houpoea officinalis, Illicium verum or Cnidium monnieri. The results provide theoretical references for the control of tuber rot of Bletilla striata.

Keywords

• bletilla striata
• tuber rot
• pathogen isolation and identification
• epicoccum sorghinum
• chinese herbal extracts