Expression of resistance gene analogs in woodland strawberry (Fragaria vesca) during infection with Phytophthora cactorum

Abstract

Important losses in strawberry production are often caused by the oomycete Phytophthora cactorum, the causal agent of crown rot. However, very limited studies at molecular levels exist of the mechanisms related to strawberry resistance against this pathogen. To begin to rectify this situation, a PCR-based approach (NBS profiling) was used to isolate strawberry resistance gene analogs (RGAs) with altered expression in response to P. cactorum during a time course (2, 4, 6, 24, 48, 96 and 192 h post-infection). Twenty-three distinct RGA fragments of the NB-LRR type were identified from a resistance genotype (Bukammen) of the wild species Fragaria vesca. The gene transcriptional profiles after infection showed that the response of most RGAs was quicker and stronger in the resistance genotype (Bukammen) than in the susceptible one (FDP821) during the early infection stage. The transcriptional patterns of one RGA (RGA109) were further monitored and compared during the P. cactorum infection of two pairs of resistant and susceptible genotype combinations (Bukammen/FDP821 and FDR1218/1603). The 5′ end sequence was cloned, and its putative protein was characteristic of NBS-LRR R protein. Our results yielded a first insight into the strawberry RGAs responding to P. cactorum infection at molecular level.

Lineage-specific duplications of NBS-LRR genes occurring before the divergence of six Fragaria species

“…Presentations of different responses to the same pathogens were commonly found in genetically heterogeneous accessions or varieties in strawberries [ 44 – 46 ]. For P .…”

“…The transcriptional responses of NBS-LRR genes showed more sensitive and fast-growing expression levels in less-susceptible cultivar ‘Sweet Charlie’ compared with those in susceptible ‘Jiuxiang’ [ 47 ]. For strawberry infection with P. cactorum , the NBS genes responded more quickly and strongly in the resistance genotype ‘Bukammen’ than in the susceptible FDP821 [ 46 ].…”

A Single-Nucleotide Polymorphism in the Promoter of a Hairpin RNA Contributes to Alternaria alternata Leaf Spot Resistance in Apple (Malus × domestica)

“…Disease resistance and susceptibility in plants are determined by the expression levels of NB-LRR genes. For instance, NB-LRR genes are expressed at higher levels in resistant than in susceptible varieties of wild strawberry (Fragaria vesca) and banana (Musa spp) during pathogen infection (Bai et al, 2013;Chen et al, 2016). Moreover, increasing NB-LRR gene expression improves plant disease resistance (Harris et al, 2013;Inoue et al, 2013).…”

De Novo Transcriptome Sequencing of the Deep-Sea-Derived Fungus Dichotomomyces cejpii and Analysis of Gliotoxin Biosynthesis Genes

“…The qRT-PCR thermal cycling condition for all reactions was 95 °C for 1 min 50 s, followed by 40 cycles at 95 °C for 10 s and 55 °C for 33 s. All reactions were conducted in biological triplicates, and the results were expressed as relative expression levels to the GAPDH gene. The C t (cycles threshold) values obtained were used as the original data to calculate the relative expression level of different genes to GAPDH gene by the 2 −ΔΔ C t method [ 29 , 30 , 31 ]. Each sample was analyzed in biological triplicate.…”