First Report of a Soft Rot of Banana in Mainland China Caused by a Dickeya sp. (Pectobacterium chrysanthemi)

Abstract

Banana is one of the most important fruit crops grown in China (2). A severe outbreak of a soft rot of banana occurred in Guangzhou, China from 2009 to 2010. The disease was characterized by an odorous soft rot of the center of the rhizome. The rot progressed up the pseudostem, destroying the growing point and causing internal decay and often accompanied by vascular discoloration. Yellowing and wilting of the leaves were also characteristic symptoms. A survey of three areas of production of Musa sapientum (cv. ABB) covering 10 ha in Guangzhou revealed that 82% of the fields were affected at an incidence ranging from 20 to 40%. Forty-five bacterial isolates were obtained from lesions on plants sampled from these fields by surface-sterilizing symptomatic tissue in 0.3% NaOCl for 10 min, rinsing the tissue sections three times in sterile water, and plating the sections on nutrient agar. Three representative isolates selected randomly were all gram negative, caused a soft rot of potato disks, utilized malonate, tested positive for phosphatase production, and tested negative for acid production from palatinose, glucopyranoside, and trehalose. A Biolog similarity index of 0.803 indicated that the three isolates had a high similarity to the Biolog reference strain of Pectobacterium chrysanthemi (Version 4.2, Biolog Inc., Hayward, CA). The 16S rDNA sequence (GenBank Accession No. 1321085) of each of the three isolates was determined (1). When compared with sequences in GenBank, the highest degree of sequence similarity was with P. chrysanthemi AF373199. On the basis of a phylogenetic tree of the sequences, the three bacterial isolates are related to Pectobacterium (100% bootstrap values). On the basis of two diagnostic methods, the three isolates were identified as P. chrysanthemi. However, according to Samson et al. (3), they are a Dickeya sp. Additional genetic comparisons with type strains will be needed for the strains to be assigned to a known species of Dickeya. Pathogenicity of each of the three strains on M. sapientum (cv. ABB) was confirmed by injecting 60 40-day-old seedlings each with 5 ml of a suspension of the isolate (108 CFU/ml) into the rhizome. Sixty plants of the same cultivar injected with sterile water served as the control treatment. After 48 h, yellowing and wilting of the leaves, similar to symptoms observed on field plants, were observed on all inoculated seedlings for each of the three bacterial strains. There were no symptoms on the control plants. Koch's postulates were fulfilled by reisolating bacteria from lesions on the leaves of inoculated seedlings. The reisolates were identical to the inoculated strains in biochemical characteristics. Bacteria characteristic of the inoculated strains were not reisolated from the control plants. To our knowledge, this is the first report of a Dickeya sp. causing soft rot of banana in mainland China. References: (1) W. S. Kaneshiro et al. Plant Dis. 92:1444, 2008. (2) Y. P. Ke et al. China Trop. Agric. 1:14, 2008. (3) R. Samson et al. Evol. Microbiol. 55:1415, 2005.

Screening, Identification and Efficacy Evaluation of Antagonistic Bacteria for Biocontrol of Soft Rot Disease Caused by Dickeya zeae

“…It also threatened different rice-cultivated areas in many Southeast Asian countries and Europe [6,15]. On banana, the incidence and severity of soft rot disease has increased since it first broke out in Guangzhou in 2009 [16], resulting in a 20% to 70% incidence, and even 90% in some plantations from 2010 to 2012 in Guangdong Province [4]. Banana infected by D. zeae was also found in Ivory Coast, Jamaica, Panama and Martinique [1,6].…”

Genome Sequence of the Banana Pathogen Dickeya zeae Strain MS1, Which Causes Bacterial Soft Rot

“…It was first found in China by Lin et al in 2009 (1) and has since become a major pathogen affecting the banana industry. The disease is characterized by massive odorous soft rot at the center or a portion of the rhizome, deteriorated with a destroyed growing point and decayed internal material, leading to vascular discoloration.…”

Pre-Harvest Finger Rot of Cavendish Banana (<em>Musa acuminate</em>) Reported from Moneragala and Badulla Districts, Sri Lanka: Identification and Confirmation of Pathogenicity of the Causal Agent

“…Based on the nature of the field symptoms, the disease could be identified as a pre-harvest soft rot of banana fingers. Several cases of bacterial soft rots of banana caused by Pectobacterium carotovorum have been reported in Korea, India and Iran (Hassanzadeh, 1990;Snehalatharani and Khan, 2010) and an outbreak of bacterial soft rot of banana caused by Dickeya zeae has been reported in Guangzhou, China in 2009 (Lin et al, 2010). Banana sheath rot is another soft rot caused by Dickeya dadantii and has been reported in China since in 2011 (Liu et al, 2016).…”