Identification of Fusarium solani causing basal stem and root rot of Crossandra infundibuliformis in Hainan, China

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RESEARCH NOTE

Identification of Fusarium solani causing basal stem and root rot of Crossandra infundibuliformis in Hainan, China F. Qiu 1 & G. Xu 1 & C. P. Xie 1

&

X. Li 1 & F. Q. Zheng 1

Received: 18 March 2020 / Accepted: 2 August 2020 # Australasian Plant Pathology Society Inc. 2020

Abstract In April 2019, a new basal stem and root rot disease, which caused severe wilting of Crossandra infundibuliformis in Jinniu Park in Haikou City, Hainan province. Plants with typical disease symptoms were random collected from Jinniu Park. The pathogen causing basal stem and root rot of C. infundibuliformis was identified as Fusarium solani from the isolates, based on morphological observation, rDNA-ITS, TEF1-α, and fRPB2 gene sequence analysis, and pathogenicity tests. This is the first report of F. solani causing basal stem and root rot on C. infundibuliformis. Keywords Crossandra infundibuliformis . Basal stem and root rot . Fusarium solani

Crossandra infundibuliformis-(Acanthaceae), flowering perennial shrub commo- nly known as firecracker flower, is native to Southern India, Sri Lanka, and Malaysia (Kaviya et al. 2012). The species is often planted in park or roadsides as it is an important ornamental flower plant. As a potted flower, it is planted 5000 pots in recent decades in Jinniu Park, Haikou, Hainan province, China. In April 2019, plants showed symptoms of rot at the base stem and roots, with an incidence of nearly 97%. The disease was primarily damaging the base stem. Initial symptoms include water-stained yellowbrown streaks on the basal stem. The streak gradually extended upward more than 10 cm and extended down to the main root and the lateral roots. Roots lesions became yellow-brown and then progressed to light-brown. When inspected, the cortex of stems and roots would easily peel off, and expose the xylem. Ultimately, infected plants withered and died en masse. This seriously affected the ornamental value. And it is extremely important to accurately identify the pathogen combining of morphological and molecular identification techniques so as to develop more effective prevention and control measures. * C. P. Xie [email protected] 1

Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests (Hainan University), Ministry of Education, College of Plant Protection, Hainan University, Haikou 570228, China

In April 2019, 20 random symptomatic C. infundibuliformis were collected from Jinniu Park (20°01′ N; 110°31′ E) in Haikou, Hainan province and washed with sterile water. Small pieces of tissue (4 × 4 mm) were cut from lesion borders, and were surfaced sterilized in 75% ethanol solution (v/v) for 30 s, followed by 3 min in 5% sodium hypochlorite. Tissue was then rinsed 3 times with sterile water, plated on potato dextrose agar (PDA), incubated at 25 °C ± 0.2 °C in constant light in a light incubator (Shanghai Hetu Technology Instrument Co., Ltd., China). Twenty isolates exhibiting similar morphological characteristics developed from all plated tissues after 4 days. We chose