The Effects of Inorganic Elements on the Reduction of Phytophthora Stem Rot Disease of Soybean, the Growth Rate and Zoospore Release of Phytophthora sojae

Abstract

The effects of several inorganic elements contained in B5 medium on Phytophthora stem rot disease reduction of Glycine max (L.) Merr. cv. Chusei-Hikarikuro, fungal growth of Phytophthora sojae isolate and zoospore release were investigated. Application of B5 solution and macro inorganic nutrients in the B5 medium prior to inoculation significantly inhibited infection, compared with controls. Various concentrations of KNO 3 , (NH 4 ) 2 SO 4 , MgSO 4 , CaCl 2 and NaH 2 PO 4 in the presence of macro inorganic nutrients were investigated in an effort to determine the elements most effective in suppressing the incidence of disease. A concentration of 2.47-24.7 mm KNO 3 and 0.1-10.2 mm CaCl 2 greatly inhibited infection. Although mycelium growth of the isolate was affected by the potassium and calcium concentration, no significant relationship was observed between inhibition of the growth rate and disease reduction at 2.47 mm KNO 3 and 0.1-5.1 mm CaCl 2 application. Disease suppression recorded in laboratory experiments using pathogen mycelium was due to the response of plant tissues rather than a direct inhibition of pathogen fungal growth by the application of potassium or calcium. The extent of disease reduction was related to an increased potassium and calcium uptake by plants, suggesting that the effective elements in reducing Phytophthora stem rot were potassium and calcium. The presence of 2.47-247 mm KNO 3 and 5.1-10.2 mm CaCl 2 decreased the release of zoospores, although 0.1-2.5 mm CaCl 2 significantly induced zoospore release. These results suggest that applying a solution containing more than 2.47 mm of potassium and 5.1 mm of calcium can decrease the incidence of disease in agricultural fields by the inhibition of zoospore release.

Genetic analysis and identification of DNA markers linked to a novel Phytophthora sojae resistance gene in the Japanese soybean cultivar Waseshiroge

“…Methods for managing economic losses to Phytophthora include fungicides (Anderson and Buzzell 1982), planting cultivars with race-specific or partial resistance (Dorrance et al 2003), soil drainage (Schmitthenner 1985), tillage practices (Workneh et al 1998), and calcium applications (Sugimoto et al 2005(Sugimoto et al , 2007(Sugimoto et al , 2008b(Sugimoto et al , 2009(Sugimoto et al , 2010. Schmitthenner (1999) reported that the most effective method to reduce damage would be to plant resistant cultivars, and genes conditioning resistance to P. sojae (Rps genes) have been widely used in commercial soybean cultivars for controlling Phytophthora stem and root rot disease (Dorrance and Schmitthenner 2000).…”

Identification of SSR markers linked to the Phytophthora resistance gene Rps1‐d in soybean

“…These isolates were tested using the virulence test on G. max ÔTanbakuroÕ and PI103091. Virulence evaluations of isolates were performed using the agar medium inoculation method, and conducted in a test bottle (width = 8 cm, height = 20 cm) using mycelia and not zoospores (Sugimoto et al 2006(Sugimoto et al , 2007. PI103091 was strongly resistant, but ÔTanbakuroÕ was susceptible to all 51 isolates.…”

“…Although this disease has been controlled with fungicides (Anderson and Buzzell 1982), calcium application (Sugimoto et al. 2005, 2007), partial resistance (Dorrance et al.…”

“…Although this disease has been controlled with fungicides (Anderson and Buzzell 1982), calcium application (Sugimoto et al 2005(Sugimoto et al , 2007, partial resistance (Dorrance et al 2003), soil drainage (Schmitthenner 1985) and tillage practices (Workneh et al 1998) for over 40 years, the most effective method to reduce the damage would be to develop resistant and tolerant cultivars of soybeans (Schmitthenner 1999). Breeding cultivars to combine Phytophthora resistance with the desirable features of ÔTanbakuroÕ is important for minimizing losses from this disease and, simultaneously, to increase farmersÕ income.…”

Analyses of the community compositions of root rot pathogenic fungi in the soybean rhizosphere soil

“…In USA, the main pathogens that cause root rot disease in soybean are Fusarium and Pythium (Ellis et al, 2013). The main pathogenic fungi in Japan are Pythium (Sugimoto et al, 2007), while the main pathogenic fungi in Canada are F. oxysporum and F. graminearum (Thomas et al, 2007). In China, the main pathogens that cause soybean root rot are Fusarium (Ding et al, 2011;Guo et al, 2011;, among these, F. solani is the dominant strain in Shandong (Wu et al, 2008;Pan et al, 2010), F. episphaeria, F. tricinctum and F. oxysporum are the main pathogens in Anhui Province, Huaibei area ), Phytophthora, F. oxysporum, F. solani (Cui et al, 2010 are the dominant pathogens in Fujian Province, and Fusarium, Rhizoctonia, Pythium, and Phytophthora are the dominant pathogens in the Xinjiang autonomous region (Qiao et al, 2007).…”