Potential for suppression of Rhizoctonia root rot is influenced by nutrient (N and P) and carbon inputs in a highly calcareous coarse-textured topsoil

Rhizoctonia solani anastomosis groups (AG)-8 and AG-2-1 and R. oryzae are ubiquitous in cereal-based cropping systems of the Columbia Plateau of the Inland Pacific Northwest and commonly infect wheat. AG-8 and R. oryzae, causal agents of Rhizoctonia root rot and bare patch, are most commonly found in fields in the low-precipitation zone, whereas R. solani AG-2-1 is much less virulent on wheat and is distributed in fields throughout the low-, intermediate-, and high-precipitation zones. Fluorescent Pseudomonas spp. that produce the antibiotic phenazine-1-carboxylic acid (PCA) also are abundant in the rhizosphere of crops grown in the low-precipitation zone but their broader geographic distribution and effect on populations of Rhizoctonia is unknown. To address these questions, we surveyed the distribution of PCA producers (Phz+) in 59 fields in cereal-based cropping systems throughout the Columbia Plateau. Phz+ Pseudomonas spp. were detected in 37 of 59 samples and comprised from 0 to 12.5% of the total culturable heterotrophic aerobic rhizosphere bacteria. The frequency with which individual plants were colonized by Phz+ pseudomonads ranged from 0 to 100%. High and moderate colonization frequencies of Phz+ pseudomonads were associated with roots from fields located in the driest areas whereas only moderate and low colonization frequencies were associated with crops where higher annual precipitation occurs. Thus, the geographic distribution of Phz+ pseudomonads overlaps closely with the distribution of R. solani AG-8 but not with that of R. oryzae or R. solani AG-2-1. Moreover, linear regression analysis demonstrated a highly significant inverse relationship between annual precipitation and the frequency of rhizospheres colonized by Phz+ pseudomonads. Phz+ pseudomonads representative of the four major indigenous species (P. aridus, P. cerealis, P. orientalis, and P. synxantha) suppressed Rhizoctonia root rot of wheat when applied as seed treatments. In vitro, mean 50% effective dose values for isolates of AG-8 and AG-2-1 from fields with high and low frequencies of phenazine producers did not differ significantly, nor was there a correlation between virulence of an isolate and sensitivity to PCA, resulting in rejection of the hypothesis that tolerance in Rhizoctonia spp. to PCA develops in nature upon exposure to Phz+ pseudomonads.

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Characterizing and Mapping Resistance in Synthetic-Derived Wheat to Rhizoctonia Root Rot in a Green Bridge Environment

Phytopathology ◽

10.1094/phyto-02-16-0055-fi ◽

2016 ◽

Vol 106 (10) ◽

pp. 1170-1176 ◽

Cited By ~ 10

Author(s):

A. K. Mahoney ◽

E. M. Babiker ◽

T. C. Paulitz ◽

D. See ◽

P. A. Okubara ◽

...

Keyword(s):

Pacific Northwest ◽

Root Rot ◽

Recombinant Inbred Lines ◽

Genetic Resistance ◽

Genotyping By Sequencing ◽

Interval Mapping ◽

Environmentally Sustainable ◽

Soilborne Disease ◽

Rhizoctonia Root Rot ◽

Green Bridge

Root rot caused by Rhizoctonia spp. is an economically important soilborne disease of spring-planted wheat in growing regions of the Pacific Northwest (PNW). The main method of controlling the disease currently is through tillage, which deters farmers from adopting the benefits of minimal tillage. Genetic resistance to this disease would provide an economic and environmentally sustainable resource for farmers. In this study, a collection of synthetic-derived genotypes was screened in high-inoculum and low-inoculum field environments. Six genotypes were found to have varying levels of resistance and tolerance to Rhizoctonia root rot. One of the lines, SPBC-3104 (‘Vorobey’), exhibited good tolerance in the field and was crossed to susceptible PNW-adapted ‘Louise’ to examine the inheritance of the trait. A population of 190 BC1-derived recombinant inbred lines was assessed in two field green bridge environments and in soils artificially infested with Rhizoctonia solani AG8. Genotyping by sequencing and composite interval mapping identified three quantitative trait loci (QTL) controlling tolerance. Beneficial alleles of all three QTL were contributed by the synthetic-derived genotype SPCB-3104.

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Registration of FC709‐2 and FC727 Sugarbeet Germplasms Resistant to Rhizoctonia Root Rot and Cercospora Leaf Spot

Crop Science ◽

10.2135/cropsci1999.0011183x003900010071x ◽

1999 ◽

Vol 39 (1) ◽

pp. 298-299 ◽

Cited By ~ 13

Author(s):

Lee Panella

Keyword(s):

Leaf Spot ◽

Root Rot ◽

Cercospora Leaf Spot ◽

Rhizoctonia Root Rot

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Effects of cultivation on Rhizoctonia root rot, cereal cyst nematode, common root rot and yield of wheat in the Victorian Mallee

Australian Journal of Experimental Agriculture ◽

10.1071/ea9910367 ◽

1991 ◽

Vol 31 (3) ◽

pp. 367 ◽

Cited By ~ 9

Author(s):

RFde Boer ◽

JF Kollmorgen ◽

BJ Macauley ◽

PR Franz ◽

Boer RF De

Keyword(s):

Grain Yield ◽

Root Rot ◽

Dry Weight ◽

Cyst Nematode ◽

Cereal Cyst Nematode ◽

Common Root ◽

Common Root Rot ◽

Root Diseases ◽

Rhizoctonia Root Rot ◽

Direct Drilling

The effects of method, time and number of cultivations on root diseases and yield of wheat were studied in a field experiment, in 1985, on a calcareous sandy loam in the Victorian Mallee. The incidence and severity of rhizoctonia root rot (Rhizoctonia solani) were higher in direct-drilled wheat than in wheat sown after cultivation. Compared with direct drilling, the severity of rhizoctonia root rot in seedlings was reduced by 40% with cultivation 20 weeks before sowing; by 70% with cultivation 1 day before sowing; and by 90% with 2 cultivations, the first at 16 weeks and the second 1 day before sowing. Cultivation generally increased the incidence of common root rot (Bipolaris sorokiniana) but had no significant effects on the severity of damage by the cereal cyst nematode (Heterodera avenae) or the number of nematode cysts produced, compared with direct drilling. The incidence and severity of root diseases, and the number of H. avenae cysts produced, were not significantly different in wheat sown after rotary hoeing than in wheat sown after scarifying. The severity of damage by H. avenae, the number of nematode cysts and the incidence of common root rot were higher (45, 70 and 36%, respectively) when scarifying was done 1 day before sowing, compared with scarifying 20 weeks earlier. Differences in sowing depth probably caused this effect since seed was sown deeper (as indicated by subcrown internode lengths) and plant emergence was less in the latter treatment. The timing and number of cultivations with a rotary hoe, however, did not significantly affect the severity of damage by H. avenae, the number of nematode cysts or the incidence of common root rot. The incidence of common root rot was correlated (r = 0.71) with the subcrown internode lengths, indicating that the deeper the seed was sown the greater the proportion of plants with the disease. Dry weight of seedlings and grain yield were negatively correlated (r = -0.79 and -0.66) with the severity of damage caused by H. avenae. Plant dry weight and grain yield were, however, not correlated with the severity of rhizoctonia root rot or the incidence of common root rot.

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Registration of FC725, FC726, and FC728 Sugarbeet Germplasms Resistant to Rhizoctonia Root Rot and Moderately Resistant to Cercospora Leaf Spot

Crop Science ◽

10.2135/cropsci1996.0011183x003600030070x ◽

1996 ◽

Vol 36 (3) ◽

pp. 819-820 ◽

Cited By ~ 2

Author(s):

L. W. Panella ◽

E. G. Ruppel

Keyword(s):

Leaf Spot ◽

Root Rot ◽

Cercospora Leaf Spot ◽

Rhizoctonia Root Rot ◽

Moderately Resistant

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Pseudomonas synxantha 2-79 Transformed with Pyrrolnitrin Biosynthesis Genes Has Improved Biocontrol Activity Against Soilborne Pathogens of Wheat and Canola

Phytopathology ◽

10.1094/phyto-09-19-0367-r ◽

2020 ◽

Vol 110 (5) ◽

pp. 1010-1017

Author(s):

Jibin Zhang ◽

Dmitri V. Mavrodi ◽

Mingming Yang ◽

Linda S. Thomashow ◽

Olga V. Mavrodi ◽

...

Keyword(s):

Root Rot ◽

Fusarium Culmorum ◽

Pythium Ultimum ◽

Gaeumannomyces Graminis ◽

Wild Type ◽

Wheat Roots ◽

Recombinant Strains ◽

Rhizoctonia Root Rot ◽

Take All

A four-gene operon (prnABCD) from Pseudomonas protegens Pf-5 encoding the biosynthesis of the antibiotic pyrronitrin was introduced into P. synxantha (formerly P. fluorescens) 2-79, an aggressive root colonizer of both dryland and irrigated wheat roots that naturally produces the antibiotic phenazine-1-carboxylic acid and suppresses both take-all and Rhizoctonia root rot of wheat. Recombinant strains ZHW15 and ZHW25 produced both antibiotics and maintained population sizes in the rhizosphere of wheat that were comparable to those of strain 2-79. The recombinant strains inhibited in vitro the wheat pathogens Rhizoctonia solani anastomosis group 8 (AG-8) and AG-2-1, Gaeumannomyces graminis var. tritici, Sclerotinia sclerotiorum, Fusarium culmorum, and F. pseudograminearum significantly more than did strain 2-79. Both the wild-type and recombinant strains were equally inhibitory of Pythium ultimum. When applied as a seed treatment, the recombinant strains suppressed take-all, Rhizoctonia root rot of wheat, and Rhizoctonia root and stem rot of canola significantly better than did wild-type strain 2-79.

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