Genetic Dissection of Phomopsis Stem Canker Resistance in Cultivated Sunflower Using High Density SNP Linkage Map.

Zahirul I Talukder,Gerald J Seiler,Christopher G Misar,Xiwen Cai,William Underwood,Guojia Ma,Lili Qi

doi:10.3390/ijms21041497

Abstract

Phomopsis stem canker (PSC) caused by Diaporthe helianthi is increasingly becoming a global threat for sunflower production. In this study, the genetic basis of PSC resistance was investigated in a recombinant inbred line (RIL) population developed from a cross between HA 89 (susceptible) and HA-R3 (resistant). The RIL population was evaluated for PSC disease incidence (DI) in seven screening trials at multiple locations during 2016–2018. The distribution of PSC DI in the RIL population was continuous, confirming a polygenic inheritance of the trait. A moderately high broad-sense heritability (H2, 0.76) was estimated for the trait across environments. In the combined analysis, both the genotype and the genotype × environment interactions were highly significant. A linkage map spanning 1505.33 cM was constructed using genotyping-by-sequencing derived markers. Marker–trait association analysis identified a total of 15 quantitative trait loci (QTL) associated with PSC resistance on 11 sunflower chromosomes, each explaining between 5.24 and 17.39% of the phenotypic variation. PSC resistance QTL were detected in two genomic regions each on chromosomes 3, 5, 13, and 17, while one QTL each was detected in the remaining seven chromosomes. Tightly linked single nucleotide polymorphism (SNP) markers flanking the PSC resistance QTL will facilitate marker-assisted selection in PSC resistance sunflower breeding.

Highlights

Phomopsis stem canker (PSC) caused by the Ascomycete fungus Diaporthe helianthi Munt.-Cvet., Mihaljc. & M
Prevalence of PSC disease was observed in all seven environments where the parents and the HA 89/HA-R3 recombinant inbred line (RIL) population were evaluated
The highest PSC incidence was observed in the Rothsay 2017 environment, followed by Crookston 2016 and Crookston 2017, suggesting that the climatic conditions were more conducive for PSC disease development in Crookston in both 2016 and 2017 and Rothsay in 2017 (Figure 1 and Figure S1)

Summary

Introduction

Phomopsis stem canker (PSC) caused by the Ascomycete fungus Diaporthe helianthi Munt.-Cvet., Mihaljc. & M. The disease was first reported in the USA in 1980, it has not been considered a serious threat to USA sunflower production until recently. A gradual increase of PSC severity has been observed in the USA since 2005 [6,7]. A dramatic increase in the prevalence of PSC disease in the USA Northern Great Plains has been reported since 2009 in the annual sunflower crop survey coordinated by the National Sunflower Association [7,8,9,10,11]. Significant damage to sunflower crops was reported in 2009 in parts of Australia, especially in areas with extended wet periods [12,13], indicating that PSC is becoming a global threat to sunflower production

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