Capsicum annuum
Creators: name: Mohammadbagheri, Leila
name: Nasr-Esfahani, Mehdi
name: Abdossi, Vahid
name: Naderi, Davood
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Solanales
Solanaceae
Capsicum
Capsicum annuum

description: 2.2. Disease severity assessment of resistant and susceptible C. annuum
The results of pathogenicity trials showed a significant difference on disease severity percentage among resistant and susceptible C. annuum genotypes to P. capsici infection, but control plants (non-inoculated C. annuum) showed no infection (Table 3) (P ≤ 0.01). The highest infection rate 100 % was on susceptible genotypes ‘37ChilP-Paleo’, ‘19OrnP-PBI’ and ‘23CherryP-Orsh’, whereas the lowest infection rate 2 % was on resistant genotypes ‘37ChilP-Paleo’, followed by ‘19OrnP-PBI’ and ‘23CherryP-Orsh’, both by 13 % disease severity (Table 4).
2.3. ISSR markers analysis
The results of tests on markers indicated that nineteen primers out of twenty one implicated primers showed a very distinct banding pattern in which 188 bands were scored and 185 bands were polymorphic. The number of bands varied from 4 bands for MBP-15 and MBP-19 primers to 18 bands for MBP-21 primer, showing the ability of these primers to distinguish the C. annuum accessions clearly. Polymorphism percentage (P%) varied in the range of 78–100 % for MBP-10 and the 21 primers used. The average P% was calculated to be 98.5 % (Supplementary Table 1) (Figs. 1 and 2). Marker index (MI) ranged from 2.00 to 6.61 and MBP-21 primer with MI = 6.61 had the highest marker index, which indicates the high efficiency of this primer in revealing polymorphism in the genotypes studied in the present investigation. (Supplementary Table 1) (Figs 1 and 2). The dendrograms were designed on similarity coefficients following Cophenetic coefficient according to which Jaccard similarity coefficient was invoked as a high similarity coefficient, and UPGMA as the best clustering algorithm, according to ISSR markers, ranged from 0.31 to 0.92. The greatest similarity was observed between the C. annuum accessions ‘20GreenP-PBI’ and ‘21OrnP-Banana’ (SC = 0.92) (Figs 1 and 2). Based on the dendrogram depicted in Fig. 1, the C. annuum accessions were divided into five main groups.
Principal Coordinate Analysis (PCA) showed a strong agreement with the results of ISSR markers, dividing the C. annuum accessions into five distinct genetics variable groups (Fig. 2), of which three groups had the most accessions. The first group contained all resistant and partially resistant genotypes; the second group contained all very susceptible genotypes, and the third group contained all susceptible genotypes. The presence of the resistant genotype, ‘37ChilP-Paleo’ in the susceptible group indicates that this C. annuum accession is similar to the susceptible genotypes in terms of the genetic parameters, despite its difference with the other cluster C. annuum accessions in reaction to RCR disease (Figs. 1 and 2), indicating there was no correlation, r = 0.058 ns between resistant and genetic variability of the C. annuum accessions.
* = Significant at 5 % probability level, ** = Significant at 1 % probability level, ns = Not significant, DF = degree of freedom, CV = coefficient of variation.
- Means in each column having same letter are not significantly different according to LSD test. - The heights and diameters are in centimeter (cm.) weights in grams (gr.) and volumes in millimeters (mm 3.).
2.4. Assessment of enzyme activity
Peroxidase (POX) activity was significantly induced 1 week after inoculation with P. capsici in the resistant and susceptible C. annuum, compared with the controls (Fig. 3A) (P ≤ 0.05). However, the increase was much more pronounced in resistant ‘37ChilP-Paleo’ by 1.8-fold, followed by resistant ‘23CherryP-Orsh’ and ‘19OrnP-PBI’, with 1.5- and 1.6-fold increases, respectively. By contrast, there was no significant increase in the inoculated susceptible genotypes, 1 week after inoculation in comparison to controls (Fig. 3A).
Activity of Superoxide dismutase (SOD) also increased significantly in the treated C. annuum resistant to P. capsici (Fig. 3B) (P ≤ 0.05). Increases in SOD activity in resistant and susceptible genotypes occurred 1 week after inoculation. The highest SOD activity was recorded in the leaves of the resistant C. annuum ‘23CherryP-Orsh’ (10-fold compared to controls), followed by ‘37ChilP-Paleo’ with 4-fold increase, and ‘19OrnP-PBI’ with 2-fold 1 week after inoculation. There was no significant difference in SOD activity in susceptible ‘26BP-Rstarlet’, ‘2BP-PBI’ and ‘24BP-301’ compared to the controls.
Screening tests were performed for all genotypes in a greenhouse with average temperature of 25 ± 2 ◦ C, relative humidity of about 60 % and a photoperiod of approximately 12–14 h daylight.*Bell Pepper-Red-Hybrid –Starlet.**The Joy of Plants.CO.UK. Means in each column having same letter are not significantly different according to LSD test.
- C.V = 12.4 %.
- Means in each column having same letter are not significantly different according to LSD test.
Activity of Polyphenol oxidase (PPO) in the C. annuum genotypes, resistant and or susceptible to P. capsici was significantly induced by inoculation with other fungi (Fig. 3C) (P ≤ 0.05), but this induction was higher in the resistant ‘37ChilP-Paleo’, ‘23CherryP-Orsh’ and ‘19OrnPPBI’ by almost 2-fold, when compared to the susceptible genotypes, 1 week after inoculation. There was no significant variation in PPO activity between the susceptible genotypes and controls 1 week after inoculation.
Catalase (CAT) activities showed the same trend in both inoculated resistant and susceptible C. annuum genotypes (Fig. 3D) (P ≤ 0.05). The highest activity was recorded in C. annuum ‘23CherryP-Orshat’ by 1.5- fold 1 week after inoculation. However, no significant increase was observed in the rest of the inoculated resistant and susceptible C. annuum genotypes (Fig. 3D).
Phenylalanine ammonia-lyase (PAL) activity increased significantly (P ≤ 0.05) in the resistant and susceptible C. annuum genotypes (Fig. 3E). The highest PAL activity (5.5-fold) was observed in the resistant ‘19OrnP-PBI’, followed by ‘23CherryP-Orshat’ by 5.3-fold and ‘37ChilP-Paleo’ with 2.6-fold increase. For all other genotypes there was no significant increase after inoculation (Fig. 3E).
Glucanase activities also showed the same trend in both inoculated resistant and susceptible C. annuum genotypes (Fig. 3F) (P ≤ 0.05). The highest activity was recorded in C. annuum ‘19OrnP-PBI’ by 2.1-fold 1 week after inoculation, followed by ‘37ChilP-Paleo’, 1.5-fold. However, there was a reduction trend in the three inoculated susceptible C. annuum genotypes by 1.0, 1.9 and 2.2-fold compared to non-inocutated controls (Fig. 3F).
Phenolic content was also significantly induced by inoculation with P. capsici in the resistant and susceptible C. annuum (Fig. 3G) (P ≤ 0.05). However, the increase was much more pronounced in resistant genotypes by 1.6, 1.7 and 1.4 respectively. There was also a significant increase in the inoculated susceptible genotypes ‘26BP-RStarlet’ and ‘2BP-PB’ I by 1.2 and 1.1-fold compared to non-inocutated controls, and decrease in ‘24BP-301’ by 1.5-fold (Fig. 3G).
There was no significant correlation (r = 0.058 ns) between resistance and genetic variability, and also between genetic variability and enzyme activity levels. But, in contrast, there was a highly significant and direct correlation between the resistance, bio-mass parameters and enzyme activity levels.
description: Published as part of Mohammadbagheri, Leila, Nasr-Esfahani, Mehdi, Abdossi, Vahid & Naderi, Davood, 2021, Genetic diversity and biochemical analysis of Capsicum annuum (Bell pepper) in response to root and basal rot disease, Phytophthora capsici, pp. 1-10 in Phytochemistry (112884) (112884) 190 on pages 2-6, DOI: 10.1016/j.phytochem.2021.112884, http://zenodo.org/record/8257941