Commercial Pepper Cultivars Research Articles

Symptoms and disease virulence assessment in commercial pepper cultivars caused by Pepper chat fruit viroid

Symptoms and disease virulence assessment in commercial pepper cultivars caused by Pepper chat fruit viroid

Molecular detection of resistance‐breaking strain Cucumber mosaic virus (rbCMV) (Cucumovirus; Bromoviridae) on resistant commercial pepper cultivars in Turkey

AbstractThe cultivation of pepper (Capsicum annuum), a significant crop worldwide, is severely affected by a number of viral agents. In Antalya province, it was observed that pepper varieties possessing the cmr1 allele that provides resistance against CMV‐P0 isolate of CMV were affected in 2019 and 2020. Typical symptoms of CMV are emerging at an alarming rate in resistant pepper plants. Afterward, virus mechanical inoculation was carried out under controlled conditions on the five commercial resistant and susceptible varieties. The success of the inoculation studies was determined by RT‐PCR using CMV CPG‐specific primers. All commercial varieties carrying the resistance cmr1 gene showed disease symptoms. For complete genome analysis, RNA from a pepper plant carrying the cmr1 gene was sequenced using Illumina‐HiSeq 2000. BLAST analyses of the obtained complete genome sequence were carried out. The breaking (CMV‐P1) and non‐breaking isolates (CMV‐P0), which were previously described in conducted studies, were analysed and aligned for SNPs. SNP mutations in these nucleotide regions were similar to resistance‐breaking and completely different from non‐breaking isolates. Our study results revealed that the CMV‐P1 isolate obtained from pepper samples carrying cmr1 resistance has been shown to be able to overcome both field and laboratory conditions. To our knowledge, this is the first report of resistance‐breaking CMV‐P1 strain on pepper varieties in Turkey.

Screening for pathotype-specific resistance to broad bean wilt virus 2 and cucumber mosaic virus in pepper (Capsicum annuum L.)

AbstractTwo aphid-transmitted RNA viruses, broad bean wilt virus 2 (BBWV2) and cucumber mosaic virus (CMV), are the most prevalent viruses in Korean pepper fields and cause chronic damage in pepper production. In this study, we employed a screening system for pathotype-specific resistance of pepper germplasm to BBWV2 and CMV by utilizing infectious cDNA clones of different pathotypes of the viruses (two BBWV2 strains and three CMV strains). We first examined pathogenic characteristics of the BBWV2 and CMV strains in various plant species and their phylogenetic positions in the virus population structures. We then screened 34 commercial pepper cultivars and seven accessions for resistance. While 21 pepper cultivars were resistant to CMV Fny strain, only two cultivars were resistant to CMV P1 strain. We also found only one cultivar partially resistant to BBWV2 RP1 strain. However, all tested commercial pepper cultivars were susceptible to the resistance-breaking CMV strain GTN (CMV-GTN) and BBWV2 severe strain PAP1 (BBWV2-PAP1), suggesting that breeding new cultivars resistant to these virus strains is necessary. Fortunately, we identified several pepper accessions that were resistant or partially resistant to CMV-GTN and one symptomless accession despite systemic infection with BBWV2-PAP1. These genetic resources will be useful in pepper breeding programs to deploy resistance to BBWV2 and CMV.

Boron and maturity effects on biochemical parameters and antioxidant activity of pepper ( Capsicum annuum L.) cultivars

Pepper fruit (Capsicum annuum L.) is one of the best sources of carotenoids, carbohydrates, flavonoids, phenols, and antioxidant activity important in the human diet. The levels of bioactive compounds are variable and may be affected by cultivar, maturity stage, and boron concentration in the soil solution. A greenhouse experiment was conducted with the pepper cultivars Solario, Osho, Odysseo, and Arlequin treated with 5 boron concentrations (0.5, 1, 2.5, 5, and 10 mg B L -1 ) for 70 days. Fruits were sampled at 40 and 70 days and the concentration of carbohydrates, carotenoids, flavonoids, total phenols, and antioxidant activity (FRAP, DPPH) were measured. The experiment included 10 plants per B treatment and cultivar, with a total of 200 plants. The results obtained in this study showed that B toxicity reduced the level of carbohydrates in four commercial pepper cultivars grown in Greece and in other countries. The levels of carotenoids, flavonoids, and phenols were a function of pepper cultivar and boron treatment. Fruit maturation increased the level of carbohydrates, phenols, flavonoids, and antioxidant capacity. The cultivar Solario had the highest phenol concentration and also the highest FRAP value among the tested cultivars. In conclusion, boron toxicity decreased carbohydrate concentration and modified antioxidant activity in pepper fruit.

Demography and population projection of Myzus persicae (Sulz.) (Hemiptera: Aphididae) on five pepper (Capsicum annuum L.) cultivars

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is a major pest of pepper. In this study, we collected data on the development, survival, fecundity, and proportion of apterous and alate forms of green peach aphid reared on five commercial pepper cultivars (Amiral, Erciyes, Mert, Mertcan, and Naz) at 25 ± 1°C, 60 ± 5% RH, and a photoperiod of 16:8 (L:D) h. We analyzed the life history raw data by using the age-stage, two-sex life table. The shortest development time (6.66 days) and highest fecundity (62.68 individuals) occurred on the Erciyes cultivar. The highest intrinsic rate of increase (r = 0.332 d−1), finite rate of increase (λ = 1.394 d−1), net reproductive rate (R0 = 62.7 offspring) and shortest mean generation time (T = 12.45 d) also occurred on the Erciyes cultivar; while the lower fitness occurred on the Amiral, Mertcan and Naz cultivars. Our results compared differences in the population growth rate of M. persicae on different pepper cultivars. This information will be useful to individuals working in pest management programs particularly those involving M. persicae.

Etiological and epidemiological concerns about Pepper root and lower stem rot caused by Fusarium oxysporum f. sp. radicis-capsici f. sp. nova

Inoculum sources of Fusarium oxysporum f. sp. radicis-capsici and host susceptibility were studied in commercial pepper cultivars and related Capsicum spp. The pathogen could not be identified in irrigation water or in the microbiologically enriched potting medium, or associated with the seeds used in the nursery where the disease was initially reported in Spain. Although the disease was asymptomatic on older pepper plants, pathogenic strains could still be isolated from the soil of those greenhouses where the disease had been previously observed. Host susceptibility in commercial pepper cultivars and related Capsicum spp. was studied. All pepper cultivars tested (n = 19), including three rootstocks, developed symptoms when inoculated with Fusarium oxysporum f. sp. radicis-capsici. Three C. baccatum accessions and one C. annuum accession exhibited resistance, whereas two C. chinense accessions showed only partial resistance. The disease symptoms could not be distinguished from those caused by one F. oxysporum f. sp. capsici isolate, and molecular analysis also showed identical tef sequences for both formae speciales.

Screening of Wild and Cultivated Capsicum Germplasm Reveals New Sources of Verticillium Wilt Resistance.

Verticillium wilt caused by Verticillium dahliae is an important soilborne disease of pepper (Capsicum species) worldwide. Most commercial pepper cultivars lack resistance to this pathogen. Our objective was to identify resistance to two V. dahliae isolates in wild and cultivated Capsicum accessions from the core collection of the National Plant Germplasm System of the USDA. Screening of 397 Capsicum accessions against two V. dahliae isolates (Vdca59 and VdCf45) was performed in a greenhouse. Seventy-eight accessions selected from this screen were further evaluated in a follow-up experiment. In total, 21 (26.9%) and 13 (16.6%) Capsicum accessions tested were resistant to Verticillium wilt when inoculated with V. dahliae isolates VdCa59 and VdCf45, respectively. Eight accessions (Grif 9073, PI 281396, PI 281397, PI 438666, PI 439292, PI 439297, PI 555616, and PI 594125) were resistant to Verticillium wilt against both V. dahliae isolates. On the basis of Germplasm Resources Information Network data, two of the Capsicum annuum accessions (Grif 9073 and PI 439297) were also resistant to Phytophthora root rot disease. These sources of multiple disease resistance will be useful to pepper breeding programs.

Evaluation of Pepper Fruit for Resistance to Phytophthora capsici in a Recombinant Inbred Line Population, and the Correlation with Fruit Shape.

Phytophthora capsici causes fruit, root, and foliar blight on pepper (Capsicum annuum) in field production. Breeding for disease-resistant commercial pepper cultivars is essential to long-term management of P. capsici. In this study, the severity of Phytophthora fruit rot was evaluated in an F6 recombinant inbred line population between CM334, a landrace from Mexico, and the commercial 'Early Jalapeño'. The two parents and 67 progeny lines were evaluated for fruit rot resistance at 3 and 5 days post inoculation (dpi) using three P. capsici isolates. Fruit shape was also evaluated for each line, and the correlation between shape and disease symptoms was investigated. Significant differences were detected among lines in lesion area measured 3 and 5 dpi, and in phenotypic traits (fruit length, width, and shape index). Of the fruit phenotypic traits measured, only fruit shape index had a significant, albeit weak (r = 0.2892, P = 0.02), correlation with lesion area when inoculated, and with only one of the three isolates of P. capsici evaluated. These results suggest that breeding for fruit rot resistance in pepper will have minimal linkage with fruit shape in the CM334 background.

국내 시판 고추 품종의 역병 저항성

2008년도부터 2010년도에 걸쳐 국내에 판매되고 있는 고추 품종의 역병 저항성을 평가하였으며 특히 2010년도에는 대표적인 고추 재배지역에서 수집한 3개의 역병균주에 전년도의 시험에서 선발된 품종을 접종하여 저항성과 아울러 품종과 균주간의 특이적 반응을 조사하였다. 국내에 판매되는 품종들은 비교적 높은 수준의 저항성에서 이병성 품종에 이러는 연속적 분포를 보였다. 특히 품종명에 역병 저항성을 의미하는 '역강' 혹은 'PR'을 앞에 붙인 품종들 중에 역병 저항성이 매우 낮거나 없는 품종도 다수 발견되어 품종선택에 재배농가의 주의가 요망되었으며, 국가의 품종등록 및 보급체계에서 품종의 저항성인증체계의 도입도 필요한 것으로 나타났다. 2008-2009년도의 시험에서 선발된 품종을 3개 지역균주에 접종한 결과 Pc005(밀양) 균주에는 대목용 품종인 '탄탄'을 제외한 모든 노지재배용 품종들은 모두 이병성을 나타내었다. Pc003(영양) 균주보다 Pc002(괴산) 균주가 병원력이 더 강한 것으로 나타났으며, 품종의 균주에 특이적인 반응도 관찰되어 몇 가지 품종은 영양균주에는 저항성으로 나타났으나 괴산균주에는 이병성으로 나타났다. 병원균의 병원성 변이와 품종과 병원균간 특이적 반응에 대응한 농가지도와 품종 육종방안에 대하여 논의하였다. Resistance to Phytophthora blight (Phytophthora capsici Leonian) of commercial cultivars of Capsicum pepper in Korea were evaluated from 2008 to 2010. In 2008 and 2009, the cultivars were tested for resistance to the Pc003 isolate collected in Youngyang, Gyeongbuk province. In 2010, the selected cultivars in the previous years were tested by inoculating with 3 isolates obtained from the pepper plants in Miryang in Gyeongnam province, Youngyang in Gyeongbuk province, and Goesan in Chungbuk province. A continuous variation in resistance from highly resistant to susceptible was observed among the commercial pepper cultivars. It was also noted that some cultivars, although their names were initiating with 'Yeokgang' or 'PR' meaning Phytophthora resistance, were very low in resistance or susceptible. When the resistant cultivars selected in 2008 and 2009 experiment were inoculated with the 3 isolates, all the commercial cultivars except a rootstock, 'Tantan', succumbed to the exceptionally virulent Pc005 (Miryang) isolate. Pc002 (Goesan) was a little more virulent than Pc003 (Youngyang). A few cultivars resistant to Pc003 (Youngyang) were severely infected by Pc002 (Goesan). Significant interaction in analysis of variance suggested the differential interactions between cultivars and pathogen isolates. Strategies to breed cultivars having high level of resistance to the highly variable pathogenic fungus, Phytophthora capsici, were discussed.

Characterization of two recessive genes controlling resistance to all races of bacterial spot in peppers

Bacterial spot, one of the most damaging diseases of pepper, is caused by Xanthomonas euvesicatoria. This pathogen has worldwide distribution and it is particularly devastating in tropical and sub-tropical regions where high temperatures and frequent precipitation provide ideal conditions for disease development. Three dominant resistance genes have been deployed singly and in combination in commercial cultivars, but have been rendered ineffectual by the high mutation rate or deletion of the corresponding cognate effector genes. These genes are missing in race P6, and their absence makes this race virulent on all commercial pepper cultivars. The breeding line ECW12346 is the only source of resistance to race P6 in Capsicum annuum, and displays a non-hypersensitive type of resistance. Characterization of this resistance has identified two recessive genes: bs5 and bs6. Individual analysis of these genes revealed that bs5 confers a greater level of resistance than bs6 at 25 degrees C, but in combination they confer full resistance to P6 indicating at least additive gene action. Tests carried out at 30 degrees C showed that both resistances are compromised to a significant extent, but in combination they provide almost full resistance to race P6 indicating a positive epistatic interaction at high temperatures. A scan of the pepper genome with restriction fragment length polymorphism and AFLP markers led to the identification of a set of AFLP markers for bs5. Allele-specific primers for a PCR-based bs5-marker have been developed to facilitate the genetic manipulation of this gene.

Resistance of Pepper Cultivars and Accessions of Capsicum spp. to Sclerotinia sclerotiorum.

Sclerotinia stem and fruit rot, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a potentially serious disease of bell peppers (Capsicum annuum L.), affecting both seedlings and mature plants. Management options for the disease are limited and information is not available on resistance in Capsicum spp. to this pathogen. The level of resistance of 12 commercial pepper cultivars and 110 Capsicum spp. accessions to Sclerotinia sclerotiorum was determined by using limited-term and ascospore inoculation methods. None of the commercial cultivars tested were resistant to Sclerotinia stem rot. Stem rot incidence among the Capsicum spp. accessions tested by ascospore inoculation ranged from 0 to 100%. Fifty-eight accessions had significantly less stem disease than the susceptible commercial cultivar Marengo. There was no correlation between results of the limited-term and ascospore inoculation tests. These results demonstrate for the first time that a high level of Sclerotinia stem rot resistance exists among the Capsicum spp. accessions. Several accessions may be suitable for use in breeding programs to increase resistance in commercial pepper cultivars.

Field Isolates of Tomato spotted wilt virus Overcoming Resistance in Pepper and Their Spread to Other Hosts in Italy.

Isolates of Tomato spotted wilt virus (TSWV) severely and systemically infecting commercial pepper cultivars with resistance introgressed from Capsicum chinense PI152225 were found in Albenga (northwestern Italy) in July 2000. Experimentally, these resistance-breaking (RB) isolates overcame the resistance in C. chinense PI152225, but they produced infection in other hosts similarly to non-RB isolates from the same area. The RB isolates were indistinguishable from TSWV by serology and electron microscopy, and they were efficiently transmitted by Frankliniella occidentalis. Such isolates were recovered on the same farm in tomato, pepper, and artichoke 2 and 12 months later, suggesting natural spread from the resistant plants and survival. The RB isolates survived in experimental mixed infections with a non-RB isolate in susceptible pepper and C. chinense, but cross-protection in pepper acted against them. Commercial TSWV-resistant pepper but not resistant tomato cultivars from different companies were susceptible to these RB isolates after mechanical inoculation. Similar isolates were not detected among TSWV samples collected from 1993 to 2000 in the area. The management of TSWV and thrips using resistant pepper cultivars is discussed.

A Tobamovirus Causing Heavy Losses in Protected Pepper Crops in Spain

AbstractDuring a four‐year (1982–1985) survey of plant viruses infecting pepper cultivars grown under plastic in the Southeastern region of Spain, a tobamovirus was found to be the major disease agent of this crop. The virus produces slight or no symptoms on the leaves, but causes chlorotic mottling, malformation and reduction in size with occasional necrosis on the fruits and was able to infect all commercial pepper cultivars tested, including those resistant to other tobamoviruses, causing a catastrophic disease. The biological and serological characterization of the virus showed that it is very similar to pepper mild mottle virus (PMMV) (Wetteret al. 1984) and therefore we have termed it as Spanish strain of PMMV (PMMV‐S). The need of grouping all the so‐called “pepper strains” of tobacco mosaic virus (TMV) as a new distinct member of the tobamovirus group with the name of PMMV is emphasized.