Genetic diversity of pepper(Capsicum spp.) germplasm resources in China reflects selection for cultivar types and spatial distribution

Pepper（Capsicum spp.） is an important vegetable crop in the world. Now the pepper in China contributes one-third of the world＇s peppers production. Genetic diversity of the pepper germplasm of China is expected interesting to know. To explore the structure of genetic diversity in Chinese pepper germplasm resources and possible relationship with cultivar types or geographic origin, we sampled and compared 372 Gen Bank pepper accessions（local cultivars and landraces） from 31 provinces, autonomous regions and municipalities of China and 31 additional accessions from other countries. These accessions were genotyped using 28 simple sequence repeat（SSR） markers spanning the entire pepper genome. We then investigated the genetic structure of the sampled collection using model-based analysis in STRUCTURE v2.3.4 and examined genetic relationships by the unweighted pair-group method of mathematical averages（UPGMA） in MEGA. In addition to geographic origin, we evaluated eight plant and fruit traits. In total, 363 alleles were amplified using the 28 SSR primers. Gene diversity, polymorphism information content and heterozygosity of the 28 SSR loci were estimated as 0.09–0.92, 0.08–0.92 and 0.01–0.34, respectively. The UPGMA cluster analysis clearly distinguished Capsicum annuum L. from other cultivated pepper species. Population structure analysis of the 368 C. annuum accessions uncovered three genetic groups which also corresponded to distinct cultivar types with respect to the plant and fruit descriptors. The genetic structure was also related to the geographic origin of the landraces. Overall results indicate that genetic diversity of Chinese pepper landraces were structured by migration of genotypes followed by human selection for cultivar types in agreement with consumption modes and adaptation to the highly diversified agro-climatic conditions.

Chilli Pepper (<i>Capsicum</i>Spp.) Diversity, Production and Fungal Contamination Management in Benin

The present study was carried out in the form of a survey with the aim of listing and describing the technical itineraries of production, storage and conservation used in six departments of high production of chilli pepper in Benin. The survey was conducted on the basis of a questionnaire in the six departments of Benin: Ouémé, Plateau, Atlantic, Littoral, Zou and Collines. The survey collected information on the socio-economic characteristics of producers, the varieties of chilli pepper grown, and the current technical itineraries used for the production, storage and conservation of chilli pepper. On the other hand, it also gave an idea of the constraints that prevent the production of chilli pepper of good sanitary quality. The results of this survey show that three varieties of chilli peppers are the most produced and consumed in Benin. These are the Gbotakin variety (Capsicum chinense), the Afundja variety (Capsicum annuum) and the Danhomètakin variety (Capsicum frutescens). The technical itineraries related to the cultivation of these chilli peppers varieties are the same in the six study departments. Unfortunately, their contamination sometimes starts at the nursery stage, passing through the field where other contaminants are added and develop until harvest. After harvest, contamination can continue in storage and finally reach the consumer if proper measures are not taken. The inappropriate or inadequate use of phytosanitary products in the chilli pepper industry is also a source of illness for consumers of this vegetable fruit. Training of producers on the best technical itineraries for the production and storage of chilli peppers is essential to revitalize and develop this sector by improving the sanitary quality of the chilli peppers produced in Benin.

Resistance Evaluation of Capsicum spp. Germplasm to Meloidogyne incognita

[Objective] This study aimed to screen out hot pepper germplasms highly resistant to Meloidogyne incognita, thereby providing resistant resources for hot pep- per breeding. [Method] Comprehensive analysis combining cluster analysis and sub- ordinate function was conducted through determining related resistance indexes of 67 hot pepper germplasms 50 days after inoculated with M. incognita. [Result] The effects of M. incognita on related resistance indexes were significantly different am- ong the hot pepper germplasms. Egg index and gall index had abundant genetic variation with variation coefficients of 143.16% and 118.95%, respectively. Based on the gall indexes, cluster analysis of hot pepper germplasms was performed. The 67 hot pepper germplasms were divided into 4 groups （resistant, moderately resistant, susceptible and high susceptible）. The resistance intensity of the hot pepper germplasms were ranked according to the sum of subordinate function values of various resistance indexes. The total function values of Rela 2 and L506M were the largest （2.00）, indicating that these two germplasms were immune to M. incognita. The total function values of L287-2, L522-1M, L504M, L515-2, 13SM100-1, L512M, L292-1, L319, L316, L317, 13SM87-1 and Rela 5 were larger than 1.95, indicating that these germplasms were highly resistant to M. incognita. [Conclusion] This study could provide certain resistant resources for resistance breeding of hot pepper to M. incognita.

Effects of Chlorine Dioxide Gas on Postharvest Physiology and Storage Quality of Green Bell Pepper (Capsicum frutescens L.var.Longrum)

The effects of treatment of chlorine dioxide （C1Oz） gas on postharvest physiology and preservation quality of green bell peppers were studied. Green bell peppers were collected in bags and treated with 0, 5, 10, 20, and 50 mg L^-1 ClO2 gas at 10±0.5℃ for over 40 d, and the changes in postharvest physiology and preservation quality of the peppers were evaluated during the storage. The inhibition of rot of the peppers was observed for all the tested ClO2 gas treatments. The rot rates of the treated samples were 50% lesser than those of the control after day 40 of storage. The highest inhibitory effect was obtained after 50 mg L^-1 ClO2 gas treatment, where the peppers did not decay until day 30 and showed only one-fourth of the rot rate of the control at day 40 of storage. The respiratory activity of the peppers was significantly （P〈0.05） inhibited by 20 and 50 mg L^-1 ClO2 treatments, whereas no significant effects on respiratory activity were observed with 5 and 10 mg L^-1 ClO2 treatments （P〉0.05）. Except for 50 mg L^-1 ClO2, malondialdenyde （MDA） contents in the peppers treated with 5, 10, or 20 mg L^-1 ClO2 were not significantly （P〉0.05） different from those in the control. Degradation of chlorophyll in the peppers was delayed by 5 mg L-1ClO2, but promoted by 10, 20, or 50 mg L^-1 ClO2. The vitamin C content, titratable acidity, and total soluble solids of the peppers treated by all the tested ClO2 gas did not significantly change during the storage. The results suggested that ClO2 gas treatment effectively delayed the postharvest physiological transformation of green peppers, inhibited decay and respiration, maintained some nutritional and sensory quality, and retarded MDA accumulation.

Combining Ability Analyses of Net Photosynthesis Rate in Pepper (Capsicum annuum L.)

In perspective of breeding high-yield hybrid pepper varieties, combining ability analysis of net photosynthesis rate at different phases of flowering and fruit setting in pepper was made with 15 cross combinations from 6 parents by （1/2） n （n- 1） diallel crosses. There are relatively large differences not only in general combining ability （GCA） effect among different parents and at different phases of flowering and fruit setting, but also in specific combining ability （SCA） effect among different hybrids. There are relatively large GCA effects in late parents but relatively less GCA effects in early parents. No obvious laws have been found in the relationship between SCA effects and maturity of hybrids. Variances of SCA are larger than those of GCA. Heritability is less but influence of environment is larger. Correlation analysis of combining ability between net photosynthesis rate and agronomic character or resistances to main diseases has showed that correlation coefficients of GCA are relatively large at the medium phase and the late phase of flowering and fruit setting. Net photosynthesis rate is more relative to leaf characters and fruit characters. Correlation coefficients of SCA are relatively large at the early phase and the late phase of flowering and fruit setting. Net photosynthesis rate is more relative to leaf characters and plant characters at the early phase but to plant characters and fruit characters at the late phase. Correlation coefficients of SCA between net photosynthesis rate and resistances to main diseases are larger than those of GCA. The combining abilities of net photosynthesis rate at different phases of flowering and fruit setting are positively correlated with those of yield per plant. The combining ability is an important parameter of breeding of high photosynthesis hybrid pepper varieties.

Investigation of the Effects of Radio Frequency Water Treatment on Some Characteristics of Growth in Pepper (<i>Capsicum annuum</i>) Plants

The aim of the present study was to investigate the effect of electromagnetic radio frequency treatment of water on the growth of pepper (Capsicum annuum) plants. For this experiment, one hundred one-week old plants were divided into two groups. The first group of plants was watered with water subjected to radio frequency electromagnetic radiation from an internet router for one hour a day, while the other group was watered with tap water (control). The overall results showed changes of growth characters of plant watered with electromagnetic water. The length of pepper plants is significantly affected by the treated water, where the length of shoot was lower in plants grown under the effect of treated water (22.43 ± 7.17 cm) than those grown without treated water (28.11 ± 8.57 cm). The results revealed that the stem diameter of control plants (1.74 ± 0.39 cm) was significantly higher than that of the treated plants (1.66 ± 0.35 cm). In addition, the root length was lower in plants grown under the effect of treated water than those grown without treated water. Pepper plants watered with electromagnetic treated water exhibited marked decreases in health index, fresh and dry weight, relative water content, number of flowers and fruits/plant as well as number of seeds/fruit. In addition, the current experiment showed a significant decrease in the number of leaves, branch and flower per plant when watered with electromagnetic treated water. The results revealed that the first flowering time for plants in treated group was remarkably decelerated when compared to other plants in control group.

Disease-resistant Mechanism of Pepper against Root-Knot Nematode(Meloidogyne spp.)

The biological characteristics,damage symptoms,pathogenic mechanism,prevention and control methods of Meloidogyne spp.in pepper,as well as identification and study of pepper resistance against Meloidogyne spp.are reviewed and summarized.

AFLP Analysis of Mitochondrial DNA from a Cytoplasmic Male Sterility Line and its Maintainer in Pepper (Capsicum annuum L.)

Cytoplasmic male sterility (CMS) is a maternally inherited trait characterized by the inability of a plant to produce functional pollen, which is widespread among higher plants. CMS system is a valuable tool for plant

Purification and Biochemical Characterization of a Protease Inhibitor Ⅱ Family from Jalapeno Pepper(Capsicum annuum L.)

Capsicum annuum L. was initially domesticated in Mexico and northern Central America, and represented an ancient Neotropical plant food complex. The purpose of this paper is to report the isolation and purification of a novo-member of a protease inhibitor from jalape&ntildeo pepper (Capsicum annuum L.) (PIJP). The molecular weight of PIJP inhibitor is 5.95 kDa with 56 amino acids and 6 Cys residues with high inhibitory activity to trypsin with a Ki value of 95 nM. This inhibitor according to the alignment with homologous from NCBI and Pfam databases is a member of proteinase inhibitors II. It is worthwhile to mention a major compositional difference between the proteinase inhibitor II families which have 8 Cys residues. PIJP is the first purified proteinase inhibitor, member of this family with only 6 Cys residues.

辣椒属(Capsicum)不同野生种的组织培养与植株再生

以日本京都大学采自拉美各国的部分野生辣椒为材料,共计5个种、9个变种:C.annuum,var.annuum,C.annuum,var.mininum,C.baccatum,var.baccatum,C.baccatum,var.pendulum,C.chinense,C.frutescens,和 C.pubescens。愈伤组织诱导培养基以 MS 附加2.0mg/l NAA,0.3mg/l 6BA 较好。其中,C.baccatum,var.baccatum 和可栽培利用的 C.annuum,var.annuum 的子叶愈伤组织在 MS+0.1mg/l NAA+0.05mg/l IAA+6.6mg/l 6BA,以及 MS+0.4mg/l NAA+0.1mg/l IAA,0.1mg/l 6BA 分化培养基上均能获得再生绿苗。

膜透气性参数对朝天椒(Capsicum annuum var.conoides)自发气调包装冷藏效果的影响

以红熟期朝天椒为材料,结合自发气调包装(modified atmosphere packaging,MAP)和(9±0. 5)℃低温贮藏技术,研究了不同透气性参数的聚乙烯包装膜对朝天椒低温贮藏保鲜效果的影响。结果表明,MAP处理可有效降低朝天椒贮藏过程中的失重率,包装膜透气性参数对包装后朝天椒的贮藏品质影响具有明显差异。MAP处理中除E处理[包装膜O2和CO2透过率分别为1 865 cm3/(m2·24 h·0.1 MPa)和7 214 cm3/(m2·24 h·0.1 MPa)]加速了朝天椒的腐烂外,其他4个处理均能不同程度抑制朝天椒贮藏过程中组织相对电导率的升高,减少腐烂的发生,延缓外观品质的劣变。其中,C处理[包装膜O2和CO2透过率分别为8 087 cm3/(m2·24 h·0. 1 MPa)和31 520 cm3/(m2·24 h·0. 1 MPa)]在贮藏30 d时朝天椒商品性最好。

Study on Agrobacterium-Mediated Transformation of Pepper with Barnase and Cre Gene

This study was designed to control plant fertility by cell lethal gene Barnase expressing at specific developmental stage and in specific tissue of male organ under the control of Cre/lox system, for heterosis breeding of chili pepper （Capsicum annuum L.）. Chili pepper inbred lines （A, D, E, and I） were transformed with Cre gene and Barnase gene situated between loxp, separately, by means of Agrobacterium co-culture. In this study, we had established a high transformation system by extensive study of affecting factors including genotype, selection of marker, and lethal dose. Cotyledon with petiole from 9-11-day-old seeding was pre-cultured on media MR[MB（MS mineral＋vitamine B5）＋BA（6-Benzyladenine） 5.0 mg·L^-1 ＋IAA（indoleacetic acid） 1.0 mg·L^-1＋GA3（gibberellic acid） 1.0mg·L^-1＋sucrose 3%＋agar 6.5g·L^-1] for 2d. The explants were infected by Agrobacterium tumefaciens when their OD600（optical density at 600 nm）reached 0.6-0.9. After co-cultured for 4-5 d on media MC [MB＋BA5.0 mg·L^-1＋IAA 1.0 mg·L^-1 ＋GA3 1.0 mg·L^-1＋sucrose 3% ＋agar 6.5 g·L^-1＋AS （acetosyringone） 200μmol·L^-1, these cotyledons with petiole were cultured on selective differentiation medium in the media MT[MB medium supplemented with BA [5.0 mg·L^-1＋ IAA 1.0 mg·L^-1＋ GA3 1.0 mg·L^-1＋ AgNO3 5.0 mg·L^-1＋ CW （coconut water） 5% ＋ Km （kanamycin） 65 mg·L^-1＋ Cb （carbenicillin） 500 mg·L^-1＋ 3% sucrose ＋ agar 6.5 g·L^-1].The Kmr （kanamycin resistant） bud rosettes were elongated on selective elongation medium and rooted on rooting medium. PCR and Southern blotting analysis of Kmr plantlet indicated that the foreign genes had been integrated into the genome of pepper. The transgenic plants with Cre gene developed well, blossomed out, and set fruit normally. The transgenic plants with Barnase gene grew well with normal appearance of flower, but they showed different fertility from complete sterility, partial sterility to complete fertility, and similar results were obtained from in vitro pollen germination experiments.

Reference quality assembly of the 3.5-Gb genome of Capsicum annuum from a single linked-read library

Linked-Read sequencing technology has recently been employed successfully for de novo assembly of human genomes,however,the utility of this technology for complex plant genomes is unproven.We evaluated the technology for this purpose by sequencing the 3.5-gigabase(Gb)diploid pepper(Capsicum annuum)genome with a single Linked-Read library.Plant genomes,including pepper,are characterized by long,highly similar repetitive sequences.Accordingly,significant effort is used to ensure that the sequenced plant is highly homozygous and the resulting assembly is a haploid consensus.With a phased assembly approach,we targeted a heterozygous F1 derived from a wide cross to assess the ability to derive both haplotypes and characterize a pungency gene with a large insertion/deletion.The Supernova software generated a highly ordered,more contiguous sequence assembly than all currently available C.annuum reference genomes.Over 83%of the final assembly was anchored and oriented using four publicly available de novo linkage maps.A comparison of the annotation of conserved eukaryotic genes indicated the completeness of assembly.The validity of the phased assembly is further demonstrated with the complete recovery of both 2.5-Kb insertion/deletion haplotypes of the PUN1 locus in the F1 sample that represents pungent and nonpungent peppers,as well as nearly full recovery of the BUSCO2 gene set within each of the two haplotypes.The most contiguous pepper genome assembly to date has been generated which demonstrates that Linked-Read library technology provides a tool to de novo assemble complex highly repetitive heterozygous plant genomes.This technology can provide an opportunity to cost-effectively develop high-quality genome assemblies for other complex plants and compare structural and gene differences through accurate haplotype reconstruction.

Comparative Transcriptome Analysis between Cytoplasmic Male-sterile Line and Its Maintainer During the Floral Bud Development of Pepper

The male-sterile line has been largely used in the hybrid seed production of pepper, which can effectively improve the efficiency of hybrid seed production. However, the formation mechanism of male sterility in pepper remains unclear. In the present study, we compared the gene expression patterns between pepper cytoplasmic male sterile line 9704 A and its maintainer 9704 B during floral bud development using RNA sequencing technology. A total of 547 976 and 2 416 Differentially Expressed Genes(DEGs) were identified in the stage S1, S2 and S3, respectively,and more than 70% of the DEGs were down-regulated in the sterile line. Gene Ontology(GO), and Kyoto Encyclopedia of Genes and Genomes(KEGG) enrichment analyses were performed to further understand the functions of these identified DEGs. The results showed that the DEGs were mainly enriched in pathways of starch and sucrose metabolism, pentose and glucuronate interconversions. A number of genes, such as MS1, PME5, ATPB, and lots of transcription factors were found down-regulated in the sterile line, and we also identified a series of genes with large differences in expression patterns between sterile line and maintainer line. Collectively, our findings laid a foundation for further molecular breeding in pepper and provided new insights into its mechanism underlying the male sterility.

Lactic Acid Fermentation of Peppers

Different peppers fermentations (Capsicum annum, grossum variety) were assayed: spontaneous, native microflora supplemented individually with Lactobacillus plantarum N8, Leuconostoc mesentereroides L. or Pediococcus pentosaceus 12p and by pure or combined cultures of these lactic acid bacteria (LAB). In order to eliminate the native flora, different kinds of heat treatment were assayed. The treatment selected was heating in autoclaved after research 3/4 atmosphere and to turn off. Fermentations were carried out at 22?C and 30?C and the culture media contained 2% or 0.2% glucose and 4% NaCl. Sugar consumption, pH reduction and acid production were higher at 30℃ than at 22℃. At both temperatures, spontaneous fermentation showed a slower rate reduction in pH than inoculated samples. Diminution in pH in presence of 2% glucose was faster than at 0.2%, but minimum pH was in both case lower than 3.0. Maximum growth was reached between 2 and 5 days of fermentation in all the samples assayed. After 30 days of incubation in presence of 2% glucose the survival of LAB was nearly 5 log ufc/ml. The survival was higher at the lower temperature assayed for both glucose concentrations. Organoleptic properties of peppers fermented with a mixed culture of Leuconostoc mesenteroides and Pediococcus pentosaceus were found best by a human panel. This sample has a relation lactic acid/acetic acid of nearly 3 in the conditions assayed.

A <i>Comt</i>1 Loss of Function Mutation Is Insufficient for Loss of Pungency in <i>Capsicum</i>

The participation of O-methyltransferase (COMT) in phenylpropanoid-mediated capsaicinoid biosynthesis has long been proposed. Ferulic acid, a phenylpropanoid intermediate, is a precursor of capsaicinoid biosynthesis and is produced from caffeic acid by the action of COMT. As previously reported that silencing Comt expression caused a drastic decrease in capsaicinoid accumulation, it was presumed that a Comt loss-of-function mutation would cause loss of pungency in Capsicum. This hypothesis was tested by cloning Comt1 and Comt2 from the placenta tissue of the pungent cultivar Habanero. The phylogenetic analysis and comparison of critical amino-acid residues for enzyme function showed that the two COMTs had high similarity with the COMTs of other plant species. Moreover, as the two Comts were both expressed in placenta tissue and expressed prior to the accumulation of capsaicinoids, the two genes could be candidates for capsaicinoid biosynthesis. Second, Comt1 loss-of-function mutants were screened from the germplasm. A truncated Comt1 transcript was expressed in non-pungent pepper No.3341 caused by deletion of the genomic region. The predicted No.3341 COMT1 lacked His-265, which was absolutely necessary for enzymatic activity. Contrary to our expectations, the Comt1 mutation was not related to non-pungency of No.3341, as the deletion of Comt1 did not co-segregate with non-pungency in the F2 population obtained from crossing No.3341 with Habanero. This result was confirmed by screening several pungent accessions harboring the same Comt1 deletion mutation. Although the participation of COMT in phenylpropanoid-mediated capsaicinoid biosynthesis has long been proposed, our present study shows that Comt1 can not be a target for controlling fruit pungency.

RAPD Technique Used to Determine the Purity of Hybrid Hot Pepper Seeds

Two hybrid hot pepper varieties Xiangyan 5 and Xiangyan 10, and their parents were analyzed the polymerase chain reaction with MJ /PT 200 Peltrier Themal Cycler and DS 800 White-ultravilot Transilluminator to set up a RAPD system adaptable to the purity determination of the hy-brid seeds. Among the 39 random primers, 2 and 4 primers were found to be used effectively in Xiangyan 5 and Xiangyan 10 respectively.

Inactivation of Salmonella Species on New Mexico Green Chile Peppers by Flame Roasting

Salmonella spp. have been implicated in foodborne disease outbreaks involving chile peppers, usually in combination foods such as chile rellenos, salsa, pico de gallo, guacamole and others where the source of contamination is uncertain. Salmonella Typhimurium ATCC 14028 was used in this study to artificially inoculate green chile peppers. Green chile peppers were weighed and artificially contaminated by applying the calculated inoculation volumes of 4 o,L per g of pepper. No presumptive salmonellae were found on any of the peppers prior to inoculation with S. Typhimurium. Twenty inoculated chiles were transferred to a custom built lab-scale roaster and then flame roasted for five minutes until they were blistered on the surface, as is commonly at New Mexico supermarkets. The surface temperature of representative chiles was measured with an infrared thermometer. Flame roasting of green chile peppers is effective in reducing bacterial contaminants on fresh green chile peppers. Based on the TSAYE counts where inoculated chile peppers had a mean plate count of 7.21 and the roasted chile peppers 2.71 and 2.75, a 4.5 log reduction was seen. Results reveal the effectiveness of flame roasting on the microbiological safety and quality of roasted green chile peppers.

Technology for Hybrid Pepper Seed Production in China

History of hybrid pepper seed production, the status of annually balanced production, and innovative techniques for the large-scale seed production in China are reviewed. Helped by the technological breakthroughs in these fields, China has been the largest base for hybrid pepper seed production in the world.

辣椒种质资源PMMoV抗性基因检测与抗性鉴定

辣椒轻斑驳病毒(Pepper mild mottle virus,PMMoV)是世界范围内最严重的病原体之一,目前已报道的PMMoV包括P_(0)、P_(1)、P_(1,2)、P_(1,2,3)、P_(1,2,3,4)五种致病型。辣椒轻斑驳病毒寄主范围广、致病力强,严重影响辣椒的产量和品质,开展抗病育种是防治该病毒最为经济有效的手段。本课题组前期研究已明确了感染海南儋州辣椒种质资源圃的PMMoV为P_(1,2)致病型,为了筛选抗PMMoV的辣椒种质资源,以110份种质为材料,利用已报道的与L^(3)连锁的分子标记对辣椒种质进行检测。结果表明:在110份材料中共检测到46份辣椒种质含有与L^(3)连锁的分子标记。采用苗期人工接种鉴定方法,对含有抗性分子标记的46份辣椒种质接种PMMoV P_(1,2)致病型进行抗性鉴定。接种5 d后调查局部症状,接种20 d后调查系统症状,计算病情指数。结果表明:不同的辣椒种质在抗病性上存在显著差异,各种质的病情指数在8.86~60.00之间,对PMMoV P_(1,2)致病型表现高抗(HR)的种质为CF19-34m和19FB6-1;表现抗病(R)的种质为CCJ93-1;表现中抗(MR)的种质包括17YB32、17SCa28m、15SM39-2、14SM555×14SM1、14SM567-2、14SM526-1、14SM565-1、14SM502-1、14SM519-1、14SM504m、14SM503m、14SM519-3、14SM518-2、14SM519-2、CCJ52-1等34份;表现感病(S)的种质包括14SM514m、CCJ22-1、CCJ113-2、CCJ135-1、CCJ157-1、L537-1m、L545、CCJ87-2、CCJ133-1,获得的高抗、抗病、中抗种质占总鉴定材料的80.43%。本研究结果为创制抗辣椒轻斑驳病毒种质资源和培育抗性品种奠定基础。