Identification of Nine Pathotype-Specific Genes Conferring Resistance to Fusiform Rust in Loblolly Pine (Pinus taeda L.)

Henry Amerson,C Nelson,Saul Garcia,E Kuhlman,Thomas Kubisiak

doi:10.3390/f6082739

Henry Amerson, C Nelson + Show 3 more

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https://doi.org/10.3390/f6082739

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Abstract

Nearly two decades of research on the host-pathogen interaction in fusiform rust of loblolly pine is detailed. Results clearly indicate that pathotype-specific genes in the host interacting with pathogen avirulence cause resistance as defined by the non-gall phenotype under favorable environmental conditions for disease development. In particular, nine fusiform rust resistance genes (Fr genes) are described here including the specific methods to determine each and their localization on the reference genetic map of loblolly pine. Understanding how these and other apparent Fr genes in loblolly pine and other rust-susceptible pines impact resistance screening, parental and progeny selection, and family and clonal deployment is an important area in forest genetics research and

Highlights

Fusiform rust disease incited by the biotrophic, macrocyclic, heteroecious fungus Cronartium quercuum (Berk.) Miyabe ex Shirai f.sp. fusiforme (Cumm.) Burds. & Snow (Cqf) is endemic to oaks and pines of the southeastern United States
Focusing first on Families 10-5 and A and Isolates SC20-21 and NC2-40, the interpretation of the data in Table 1 is that Isolate SC20-21 is avirulent to a corresponding resistance gene (Fr1) that is segregating in Family 10-5
Isolate NC2-40 is avirulent to a different frequency of the resistance (Fr) gene (Fr2) that is segregating in Family A, but virulent to gene Fr1. This gene (Fr1) segregating in Family 10-5, while

Summary

Introduction

Fusiform rust disease incited by the biotrophic, macrocyclic, heteroecious fungus Cronartium quercuum (Berk.) Miyabe ex Shirai f.sp. fusiforme (Cumm.) Burds. & Snow (Cqf) is endemic to oaks and pines of the southeastern United States. Erythrobalanus, i.e., red oaks) is confined to leaf spotting, whereas damage on the aecial or non-repeating host (subgenus Pinus section Trifoliae subsection Australes, i.e., southern yellow pines) results in the formation of swollen galls on stems and/or branches of infected trees. These swellings can disrupt water flow and directly kill infected trees or weaken the stem and predispose them to future damage. Several studies have attempted to estimate the economic impact of losses due to fusiform rust disease [1,2,3]. Estimates vary considerably depending upon the criteria used for devaluation, losses throughout the southeast are likely on the order of 100s of millions of dollars annually

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