Limits...
Comparative transcriptomics of Central Asian Vitis vinifera accessions reveals distinct defense strategies against powdery mildew.

Amrine KC, Blanco-Ulate B, Riaz S, Pap D, Jones L, Figueroa-Balderas R, Walker MA, Cantu D - Hortic Res (2015)

Bottom Line: To identify potential Ren1-dependent transcriptional responses and functions associated with the different levels of resistance, we sequenced and analyzed the transcriptomes of these Central Asian accessions at two time points of PM infection.Transcriptomes were compared to identify constitutive differences and PM-inducible responses that may underlie their disease resistant phenotype.This study provides a first exploration of the functions associated with varying levels of partial resistance to PM in V. vinifera accessions that can be exploited as sources of genetic resistance in grape breeding programs.

View Article: PubMed Central - PubMed

Affiliation: Department of Viticulture and Enology, University of California , Davis, Davis, CA 95616, USA.

ABSTRACT
Grape powdery mildew (PM), caused by the biotrophic ascomycete Erysiphe necator, is a devastating fungal disease that affects most Vitis vinifera cultivars. We have previously identified a panel of V. vinifera accessions from Central Asia with partial resistance to PM that possess a Ren1-like local haplotype. In this study, we show that in addition to the typical Ren1-associated late post-penetration resistance, these accessions display a range of different levels of disease development suggesting that alternative alleles or additional genes contribute to determining the outcome of the interaction with the pathogen. To identify potential Ren1-dependent transcriptional responses and functions associated with the different levels of resistance, we sequenced and analyzed the transcriptomes of these Central Asian accessions at two time points of PM infection. Transcriptomes were compared to identify constitutive differences and PM-inducible responses that may underlie their disease resistant phenotype. Responses to E. necator in all resistant accessions were characterized by an early up-regulation of 13 genes, most encoding putative defense functions, and a late down-regulation of 32 genes, enriched in transcriptional regulators and protein kinases. Potential Ren1-dependent responses included a hotspot of co-regulated genes on chromosome 18. We also identified 81 genes whose expression levels and dynamics correlated with the phenotypic differences between the most resistant accessions 'Karadzhandahal', DVIT3351.27, and O34-16 and the other genotypes. This study provides a first exploration of the functions associated with varying levels of partial resistance to PM in V. vinifera accessions that can be exploited as sources of genetic resistance in grape breeding programs.

No MeSH data available.


Related in: MedlinePlus

Characterization of PM susceptibility in the eight V. vinifera cv (a) Micrographs of E. necator infection at 14 dpi. Bars = 0.2 mm (b) Mean visual scores of PM susceptibility in the eight cultivars. Different letters depict significant differences based on ANOVA followed by Tukey’s HSD test (P ≤ 0.05). (c) Correlation between visual scores of disease susceptibility and E. necator biomass measured by qPCR.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4591678&req=5

fig1: Characterization of PM susceptibility in the eight V. vinifera cv (a) Micrographs of E. necator infection at 14 dpi. Bars = 0.2 mm (b) Mean visual scores of PM susceptibility in the eight cultivars. Different letters depict significant differences based on ANOVA followed by Tukey’s HSD test (P ≤ 0.05). (c) Correlation between visual scores of disease susceptibility and E. necator biomass measured by qPCR.

Mentions: Two wild and five cultivated Central Asian V. vinifera accessions that display partial resistance against PM were the subject of this study (Table 1). To describe their disease phenotype, fungal growth and development of symptoms were assessed after leaf inoculation with the virulent E. necator C-strain. The fully susceptible V. vinifera cv. ‘Carignan’ was evaluated in parallel as a positive control. Conidia germination and establishment of primary appressoria were detected at 1 day post-inoculation (1 dpi) on leaves of all accessions. By 5 dpi, extensive growth and branching of fungal mycelia were observed in the susceptible ‘Carignan’ leaves, whereas in all PM-partially resistant accessions mycelial growth was restricted (Supplementary Figure S1). At 14 dpi (Figure 1a), categorical visual scores were assigned to describe disease development (Figure 1b) and correlated strongly with qPCR measurements of E. necator biomass (R2 = 0.89; P = 0.00041; Figure 1c). The greatest amount of fungal biomass and conidiophores was observed on the surface of ‘Carignan’ leaves (Figure 1a), in addition to widespread PM symptoms (i.e., white dusty appearance). Localized necrotic spots associated with appressoria, suggestive of a hypersensitive response and programmed cell death (PCD), were evident in the inoculated leaves of all PM-resistant accessions (Figure 1a). However, despite their overall similar partial resistance to the disease, the abundance of E. necator biomass and the presence of reproductive structures varied significantly across the Central Asian accessions at 14 dpi (Figure 1a). These results suggest that different mechanisms may contribute to the resistance phenotype in the different genotypes. ANOVA analysis followed by Tukey’s HSD post-hoc test (P ≤ 0.05) of both visual symptoms and biomass accumulation divided the seven Central Asian accessions into three groups (Figure 1b). Leaves of ‘Late Vavilov’ were the most infected among the Central Asian accessions, followed by ‘Husseine’, ‘Sochal’, and ‘Khalchili’. The lowest amount of E. necator growth and reproduction were present in leaves from ‘Karadzhandal’ and DVIT3351.27. Based on biomass accumulation O34-16 had similar level of resistance to the other V. vinifera spp. sativa DVIT3351.27 (Figure 1c).


Comparative transcriptomics of Central Asian Vitis vinifera accessions reveals distinct defense strategies against powdery mildew.

Amrine KC, Blanco-Ulate B, Riaz S, Pap D, Jones L, Figueroa-Balderas R, Walker MA, Cantu D - Hortic Res (2015)

Characterization of PM susceptibility in the eight V. vinifera cv (a) Micrographs of E. necator infection at 14 dpi. Bars = 0.2 mm (b) Mean visual scores of PM susceptibility in the eight cultivars. Different letters depict significant differences based on ANOVA followed by Tukey’s HSD test (P ≤ 0.05). (c) Correlation between visual scores of disease susceptibility and E. necator biomass measured by qPCR.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591678&req=5

fig1: Characterization of PM susceptibility in the eight V. vinifera cv (a) Micrographs of E. necator infection at 14 dpi. Bars = 0.2 mm (b) Mean visual scores of PM susceptibility in the eight cultivars. Different letters depict significant differences based on ANOVA followed by Tukey’s HSD test (P ≤ 0.05). (c) Correlation between visual scores of disease susceptibility and E. necator biomass measured by qPCR.
Mentions: Two wild and five cultivated Central Asian V. vinifera accessions that display partial resistance against PM were the subject of this study (Table 1). To describe their disease phenotype, fungal growth and development of symptoms were assessed after leaf inoculation with the virulent E. necator C-strain. The fully susceptible V. vinifera cv. ‘Carignan’ was evaluated in parallel as a positive control. Conidia germination and establishment of primary appressoria were detected at 1 day post-inoculation (1 dpi) on leaves of all accessions. By 5 dpi, extensive growth and branching of fungal mycelia were observed in the susceptible ‘Carignan’ leaves, whereas in all PM-partially resistant accessions mycelial growth was restricted (Supplementary Figure S1). At 14 dpi (Figure 1a), categorical visual scores were assigned to describe disease development (Figure 1b) and correlated strongly with qPCR measurements of E. necator biomass (R2 = 0.89; P = 0.00041; Figure 1c). The greatest amount of fungal biomass and conidiophores was observed on the surface of ‘Carignan’ leaves (Figure 1a), in addition to widespread PM symptoms (i.e., white dusty appearance). Localized necrotic spots associated with appressoria, suggestive of a hypersensitive response and programmed cell death (PCD), were evident in the inoculated leaves of all PM-resistant accessions (Figure 1a). However, despite their overall similar partial resistance to the disease, the abundance of E. necator biomass and the presence of reproductive structures varied significantly across the Central Asian accessions at 14 dpi (Figure 1a). These results suggest that different mechanisms may contribute to the resistance phenotype in the different genotypes. ANOVA analysis followed by Tukey’s HSD post-hoc test (P ≤ 0.05) of both visual symptoms and biomass accumulation divided the seven Central Asian accessions into three groups (Figure 1b). Leaves of ‘Late Vavilov’ were the most infected among the Central Asian accessions, followed by ‘Husseine’, ‘Sochal’, and ‘Khalchili’. The lowest amount of E. necator growth and reproduction were present in leaves from ‘Karadzhandal’ and DVIT3351.27. Based on biomass accumulation O34-16 had similar level of resistance to the other V. vinifera spp. sativa DVIT3351.27 (Figure 1c).

Bottom Line: To identify potential Ren1-dependent transcriptional responses and functions associated with the different levels of resistance, we sequenced and analyzed the transcriptomes of these Central Asian accessions at two time points of PM infection.Transcriptomes were compared to identify constitutive differences and PM-inducible responses that may underlie their disease resistant phenotype.This study provides a first exploration of the functions associated with varying levels of partial resistance to PM in V. vinifera accessions that can be exploited as sources of genetic resistance in grape breeding programs.

View Article: PubMed Central - PubMed

Affiliation: Department of Viticulture and Enology, University of California , Davis, Davis, CA 95616, USA.

ABSTRACT
Grape powdery mildew (PM), caused by the biotrophic ascomycete Erysiphe necator, is a devastating fungal disease that affects most Vitis vinifera cultivars. We have previously identified a panel of V. vinifera accessions from Central Asia with partial resistance to PM that possess a Ren1-like local haplotype. In this study, we show that in addition to the typical Ren1-associated late post-penetration resistance, these accessions display a range of different levels of disease development suggesting that alternative alleles or additional genes contribute to determining the outcome of the interaction with the pathogen. To identify potential Ren1-dependent transcriptional responses and functions associated with the different levels of resistance, we sequenced and analyzed the transcriptomes of these Central Asian accessions at two time points of PM infection. Transcriptomes were compared to identify constitutive differences and PM-inducible responses that may underlie their disease resistant phenotype. Responses to E. necator in all resistant accessions were characterized by an early up-regulation of 13 genes, most encoding putative defense functions, and a late down-regulation of 32 genes, enriched in transcriptional regulators and protein kinases. Potential Ren1-dependent responses included a hotspot of co-regulated genes on chromosome 18. We also identified 81 genes whose expression levels and dynamics correlated with the phenotypic differences between the most resistant accessions 'Karadzhandahal', DVIT3351.27, and O34-16 and the other genotypes. This study provides a first exploration of the functions associated with varying levels of partial resistance to PM in V. vinifera accessions that can be exploited as sources of genetic resistance in grape breeding programs.

No MeSH data available.


Related in: MedlinePlus