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The stay-green trait is of considerable importance in extending the shelf life of green pepper fruit (Capsicum annuum L.) and in enhancing the appearance of ornamental plants. The study revealed the genetic and regulatory mechanisms of the stay-green trait in pepper, which will aid in the selection of ornamental pepper varieties. In this study, a pepper mutant with stay-green fruit named TNX348 was identified from a germplasm resource bank. Two segregating populations were constructed using the stay-green mutant TNX348 and then used in bulked segregant analysis combined with RNA sequencing and linkage analyses. The causal gene of the stay-green trait was mapped to an approximately 131-kb region, and a senescence-induced chloroplast protein gene, CaSGR1 (Capana01g000359), was identified as a candidate gene. Sequencing analysis revealed a G → A single-base mutation of CaSGR1 in TNX348 that led to early termination of translation. Based on the single-base mutation, a single nucleotide polymorphism (SNP) marker co-segregating with the stay-green trait was developed. Furthermore, in transcriptome analysis, expression patterns of 11 hormone transduction-related transcription factors, such as abscisic acid-insensitive (ABI), abscisic acidresponsive element-binding factor (ABF), and NAC transcription factor, were similar or opposite to that of CaSGR1. The results indicated that the transcription factors might mediate chlorophyll degradation by regulating the expression of CaSGR1. [ABSTRACT FROM AUTHOR]

Hot pepper (Capsicum annuum L.) is one of the most important vegetable crops in China, but floods bring substantial decreases in production over the past several decades. In order to investigate the mechanisms of waterlogging resistance in mutant hot pepper, we measured the agronomic traits of mutant and wild-type, as well as the activities of root antioxidant enzymes and the contents of osmotic regulation substance. At the same time, we did transcriptome sequencing on the plant roots, and screened for differentially expressed genes between mutant and wild-type. The results showed that, under waterlogging stress, the mutants could grow normally, and the activities of their superoxide dismutase, peroxidase, catalase, and glutathione reductase were significantly increased, as well as the contents of proline and soluble sugar. The accumulation of malondialdehyde and hydroxyl radical in mutants was significantly reduced. Among the 61 differentially expressed genes from transcriptome analysis, 24 genes were up-regulated and 37 genes were down-regulated in mutants. After functional analysis, we found 8 genes related to the metabolism of endogenous hormone and protective enzymes, among which, auxin-induced protein related gene cap.ARATH, ethylene response related gene Cap.RAP2, MYB family related gene Cap.MYB1R1, and the 4 genes related to peroxidase Cap.POD, were significantly up-regulated in mutants, while the Capana01g001329 gene was down-regulated. These results suggest that under waterlogging stress, the mutant could enhance its resistance to waterlogging by regulating the genes involved in metabolism of endogenous hormones and protective enzymes. This study provides the scientific basis for elucidating the gene regulation network of mutant pepper under waterlogging stress. [ABSTRACT FROM AUTHOR]

To illustrate the effects of domestication on wild pepper, we compared the seed micromorphology and germination characteristics of two wild pepper strains and their corresponding cultivars. The results showed that compared to their corresponding cultivars, wild pepper seeds are significantly smaller, have more groove and ridges on the surface, higher water imbibition rate, higher germination rate and higher α-amylase activity, and digest starch granules faster. The results indicate that the smaller wild seeds are easier to spread; more grooves and ridges on the surface and higher hilum ratio benefit their water imbibition, and rapid decomposition of starch granules and higher α-amylase activity are in favor to germination. By contrast, increased seed size will lead to a reduced germination rate and decreased adaptive ability to water environmental change. Thus, seed size is the result of natural and artificial selection, and whether larger seeds of various pepper cultivars are meaningful in evolution is debatable. [ABSTRACT FROM AUTHOR]

[Objective] The aim was to improve the genetic property of peppers, the mutant population of Capsicum annuum L cultivar "6421" was constructed. [Method] The seeds of "6421" were treated with 0.2% to 1.2% ethyl methane sulfonate to identified LD50, and then 10 000 LD50 of treated seeds were sowed to construct mutant population. The agronomic characters and genetic regularity of dwarf mutants in M4 generation were analyzed. [Result] Our results showed that GR and SSR were 45.2% and 40.2% respectively at 1.0% EMS, close to LD50 with Gl (17.6) and seed VI (19.7) being half of that of control; 562 M4 mutants were identified in 2015, and the mutation could be characterized according 11 major categories and 32 subcategories; Simultaneously, we found that plant height, plant width, diameter of main-stem, length of main-stem, the number of main-stem nodes and branch of lines E29, E58, E142 and E312 were all significantly different from that of the control. The mutation of lines E29, E58 and E312 was all controlled by a single recessive gene. [Conclusion] The study first created a pepper mutant population, which provides not only the germplasm resources for further breeding but also direct and effective materials for genomic study of the pepper. [ABSTRACT FROM AUTHOR]