Limits...
Two Theobroma cacao genotypes with contrasting pathogen tolerance show aberrant transcriptional and ROS responses after salicylic acid treatment.

Fister AS, O'Neil ST, Shi Z, Zhang Y, Tyler BM, Guiltinan MJ, Maximova SN - J. Exp. Bot. (2015)

Bottom Line: Varietal differences in defence responses provide insights into the mechanisms of resistance and are a key resource for plant breeders.Transient overexpression of TcNPR1, a major transcriptional regulator of the SA-dependent plant immune system, also increased pathogen tolerance in cacao leaves.These experiments revealed critical insights regarding the molecular differences between cacao varieties, which will allow a better understanding of defence mechanisms to help guide breeding programmes.

View Article: PubMed Central - PubMed

Affiliation: The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.

No MeSH data available.


Related in: MedlinePlus

Inoculation of SA pre-treated stage C leaves from ICS1 and SCA6 with Phytophthora tropicalis. Stage C leaves were inoculated with agar plugs containing P. tropicalis mycelium 24h after water or 1mM SA treatment. Representative images of (A) water-treated ICS1 leaves, (B) SA-treated ICS1 leaves, (C) water-treated SCA6 leaves and (D) SA-treated SCA6 leaves 3 d after inoculation. Scale bars, 1cm. (E) Average lesion areas in replicate leaves were evaluated by ImageJ. Data represent means ±SE of treated leaves from 24 replicates per genotype. Letters above bar chart show the significant differences (P<0.05) determined by Fisher’s PLSD analysis. (F) Relative pathogen biomass was measured by qPCR with DNA isolated 48h after inoculation and is expressed as the ratio of P. tropicalis actin to cacao actin. Bars represent means ±SE of four biological replicates, each with three technical replicates. Letters above the bar show the significant differences (P<0.05) determined by Fisher’s PLSD analysis.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4588882&req=5

Figure 1: Inoculation of SA pre-treated stage C leaves from ICS1 and SCA6 with Phytophthora tropicalis. Stage C leaves were inoculated with agar plugs containing P. tropicalis mycelium 24h after water or 1mM SA treatment. Representative images of (A) water-treated ICS1 leaves, (B) SA-treated ICS1 leaves, (C) water-treated SCA6 leaves and (D) SA-treated SCA6 leaves 3 d after inoculation. Scale bars, 1cm. (E) Average lesion areas in replicate leaves were evaluated by ImageJ. Data represent means ±SE of treated leaves from 24 replicates per genotype. Letters above bar chart show the significant differences (P<0.05) determined by Fisher’s PLSD analysis. (F) Relative pathogen biomass was measured by qPCR with DNA isolated 48h after inoculation and is expressed as the ratio of P. tropicalis actin to cacao actin. Bars represent means ±SE of four biological replicates, each with three technical replicates. Letters above the bar show the significant differences (P<0.05) determined by Fisher’s PLSD analysis.

Mentions: At the time of collection, the ICS1 and Sca6 leaves were very similar in appearance and texture, however at the end of the 24h incubation, most of the leaf surfaces of ICS1 became chlorotic, while Sca6 leaves remained green (Fig. 1A−D). This difference was apparent until the end of the pathogen infection period. By 3 d post-inoculation, all SA and water treated leaves of both genotypes developed necrotic lesions at the sites of infection (Fig. 1A−D). Lesion areas were measured using ImageJ software (Schneider et al., 2012). Symptoms were most severe in the water-treated ICS1 leaves. The average lesion areas of SA-treated ICS1 leaves was 20% smaller compared to the water treated ICS1 leaves, though the difference was not significant (Fig. 1E). Treatment of Sca6 leaves with SA resulted in a statistically significant reduction of lesion areas. The lesions of SA treated Sca6 leaves were ~60% smaller than those of Sca6 control leaves and 80% smaller than ICS1 controls. To assess pathogen growth we extracted genomic DNA from the lesions and performed qPCR with P. tropicalis—specific primers and primers for the cacao actin gene. SA treatment significantly (P<0.05) reduced pathogen growth in both genotypes (Fig. 1F). Pathogen biomass in control Sca6 leaves was similar to SA-treated ICS1, but was further reduced in SA-treated Sca6 tissue. These results confirmed that detached leaves of ICS1 are more susceptible to P. tropicalis than Sca6 at both basal and SA-induced states. Both genotypes demonstrated an SA response that resulted in decreased lesion size and pathogen growth, however, the SA effect was greater in Sca6 (4-fold reduction in pathogen biomass accumulation) than in ICS1 (1.7-fold) (Fig. 1E, F).


Two Theobroma cacao genotypes with contrasting pathogen tolerance show aberrant transcriptional and ROS responses after salicylic acid treatment.

Fister AS, O'Neil ST, Shi Z, Zhang Y, Tyler BM, Guiltinan MJ, Maximova SN - J. Exp. Bot. (2015)

Inoculation of SA pre-treated stage C leaves from ICS1 and SCA6 with Phytophthora tropicalis. Stage C leaves were inoculated with agar plugs containing P. tropicalis mycelium 24h after water or 1mM SA treatment. Representative images of (A) water-treated ICS1 leaves, (B) SA-treated ICS1 leaves, (C) water-treated SCA6 leaves and (D) SA-treated SCA6 leaves 3 d after inoculation. Scale bars, 1cm. (E) Average lesion areas in replicate leaves were evaluated by ImageJ. Data represent means ±SE of treated leaves from 24 replicates per genotype. Letters above bar chart show the significant differences (P<0.05) determined by Fisher’s PLSD analysis. (F) Relative pathogen biomass was measured by qPCR with DNA isolated 48h after inoculation and is expressed as the ratio of P. tropicalis actin to cacao actin. Bars represent means ±SE of four biological replicates, each with three technical replicates. Letters above the bar show the significant differences (P<0.05) determined by Fisher’s PLSD analysis.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4588882&req=5

Figure 1: Inoculation of SA pre-treated stage C leaves from ICS1 and SCA6 with Phytophthora tropicalis. Stage C leaves were inoculated with agar plugs containing P. tropicalis mycelium 24h after water or 1mM SA treatment. Representative images of (A) water-treated ICS1 leaves, (B) SA-treated ICS1 leaves, (C) water-treated SCA6 leaves and (D) SA-treated SCA6 leaves 3 d after inoculation. Scale bars, 1cm. (E) Average lesion areas in replicate leaves were evaluated by ImageJ. Data represent means ±SE of treated leaves from 24 replicates per genotype. Letters above bar chart show the significant differences (P<0.05) determined by Fisher’s PLSD analysis. (F) Relative pathogen biomass was measured by qPCR with DNA isolated 48h after inoculation and is expressed as the ratio of P. tropicalis actin to cacao actin. Bars represent means ±SE of four biological replicates, each with three technical replicates. Letters above the bar show the significant differences (P<0.05) determined by Fisher’s PLSD analysis.
Mentions: At the time of collection, the ICS1 and Sca6 leaves were very similar in appearance and texture, however at the end of the 24h incubation, most of the leaf surfaces of ICS1 became chlorotic, while Sca6 leaves remained green (Fig. 1A−D). This difference was apparent until the end of the pathogen infection period. By 3 d post-inoculation, all SA and water treated leaves of both genotypes developed necrotic lesions at the sites of infection (Fig. 1A−D). Lesion areas were measured using ImageJ software (Schneider et al., 2012). Symptoms were most severe in the water-treated ICS1 leaves. The average lesion areas of SA-treated ICS1 leaves was 20% smaller compared to the water treated ICS1 leaves, though the difference was not significant (Fig. 1E). Treatment of Sca6 leaves with SA resulted in a statistically significant reduction of lesion areas. The lesions of SA treated Sca6 leaves were ~60% smaller than those of Sca6 control leaves and 80% smaller than ICS1 controls. To assess pathogen growth we extracted genomic DNA from the lesions and performed qPCR with P. tropicalis—specific primers and primers for the cacao actin gene. SA treatment significantly (P<0.05) reduced pathogen growth in both genotypes (Fig. 1F). Pathogen biomass in control Sca6 leaves was similar to SA-treated ICS1, but was further reduced in SA-treated Sca6 tissue. These results confirmed that detached leaves of ICS1 are more susceptible to P. tropicalis than Sca6 at both basal and SA-induced states. Both genotypes demonstrated an SA response that resulted in decreased lesion size and pathogen growth, however, the SA effect was greater in Sca6 (4-fold reduction in pathogen biomass accumulation) than in ICS1 (1.7-fold) (Fig. 1E, F).

Bottom Line: Varietal differences in defence responses provide insights into the mechanisms of resistance and are a key resource for plant breeders.Transient overexpression of TcNPR1, a major transcriptional regulator of the SA-dependent plant immune system, also increased pathogen tolerance in cacao leaves.These experiments revealed critical insights regarding the molecular differences between cacao varieties, which will allow a better understanding of defence mechanisms to help guide breeding programmes.

View Article: PubMed Central - PubMed

Affiliation: The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA.

No MeSH data available.


Related in: MedlinePlus