Development and application of a suite of non-pungency markers for the Pun1 gene in pepper (Capsicum spp.)

Wyatt, Lindsay E.; Eannetta, Nancy T.; Stellari, Giulia M.; Mazourek, Michael

doi:10.1007/s11032-012-9716-9

Cited by 19 publications

(16 citation statements)

References 8 publications

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“…Even though two loss-of-function pun1 alleles have been reported in other Capsicum species, including pun1 2 in C. chinense and pun1 3 in C. frutescens, no additional pun1 allele has been identified among C. annuum (Stellari et al, 2010;Stewart et al, 2007;Wyatt et al, 2012). This finding indicates that breeding for non-pungent peppers is relying on the pun1 1 allele worldwide.…”

Section: Discussionmentioning

confidence: 90%

Non-pungency in a Japanese Chili Pepper Landrace (Capsicum annuum) is Caused by a Novel Loss-of-function Pun1 Allele

et al. 2017

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Pungency in peppers is due to the presence of the alkaloid capsaicin and its analogues, collectively known as capsaicinoids. These compounds are only produced in the Capsicum genus and function as deterrents to mammals from consuming the pepper fruits. Pungency in pepper is qualitatively controlled by the Pun1 locus, which encodes a putative acyltransferase enzyme. Mutations in the Pun1 gene result in a loss of pungency, and several Pun1 loss-of-function alleles have been identified in sweet peppers to date (pun1 [1][2][3] ). However, variations in pun1 alleles have not been completely elucidated. In the present study, we report a new type of loss-of-function pun1 allele, named pun1 4 , in a Japanese sweet pepper cultivar, 'Nara Murasaki' (C. annuum). Sequence analysis at the Pun1 locus revealed that this type of Pun1 allele is caused by a single adenine nucleotide insertion in the second exon region. This insertion is unique to 'Nara Murasaki' and is not present in wild-type Pun1. This insertion causes a frameshift mutation and a change in the amino acid sequence, resulting in a truncated protein. The results of gene expression analysis indicated that the expression of Pun1 in 'Nara Murasaki' was hardly detectable, while the transcripts of this gene were strongly expressed in a pungent cultivar. In a co-segregation test, the pun1 4 genotype perfectly co-segregated with non-pungency in 103 F 2 population plants of a cross between 'Nara Murasaki' and a pungent cultivar. 'Nara Murasaki' and a DNA marker to distinguish the pun1 4 allele will be informative for understanding the domestication process of sweet peppers.

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Section: Discussionmentioning

confidence: 90%

Non-pungency in a Japanese Chili Pepper Landrace (Capsicum annuum) is Caused by a Novel Loss-of-function Pun1 Allele

et al. 2017

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“…Pun1 encodes an acyltransferase that acylates vanillylamine with a fatty acid to form a capsaicinoid. Loss-of-function pun1 alleles lead to the complete shutdown of capsaicinoid production (Stewart et al, 2005(Stewart et al, , 2007Stellari et al, 2010;Wyatt et al, 2012;Kirii et al, 2017). In addition to pun1, loss-of-function mutation in putative aminotransferase (pAMT) and putative ketoacyl-ACP reductase (CaKR1) were reported as genetic factors leading to loss of pungency (Lang et al, 2009;Koeda et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Positional differences of intronic transposons in pAMT affect the pungency level in chili pepper through altered splicing efficiency

et al. 2019

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Summary Capsaicinoids are unique compounds that give chili pepper fruits their pungent taste. Capsaicinoid levels vary widely among pungent cultivars, which range from low pungency to extremely pungent. However, the molecular mechanisms underlying this quantitative variation have not been elucidated. Our previous study identified various loss‐of‐function alleles of the pAMT gene which led to low pungency. The mutations in these alleles are commonly defined by Tcc transposon insertion and its footprint. In this study, we identified two leaky pamt alleles (pamtL1 and pamtL2) with different levels of putative aminotransferase (pAMT) activity. Notably, both alleles had a Tcc transposon insertion in intron 3, but the locations of the insertions within the intron were different. Genetic analysis revealed that pamtL1, pamtL2 and a loss‐of‐function pamt allele reduced capsaicinoid levels to about 50%, 10% and less than 1%, respectively. pamtL1 and pamtL2 encoded functional pAMT proteins, but they exhibited lower transcript levels than the functional type. RNA sequencing analysis showed that intronic transposons disrupted splicing in intron 3, which resulted in simultaneous expression of functional pAMT mRNA and non‐functional splice variants containing partial sequences of Tcc. The non‐functional splice variants were more dominant in pamtL2 than in pamtL1. This suggested that the difference in position of the intronic transposons could alter splicing efficiency, leading to different pAMT activities and reducing capsaicinoid content to different levels. Our results provide a striking example of allelic variations caused by intronic transposons; these variations contribute to quantitative differences in secondary metabolite contents.

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“…Previous studies on various pepper varieties reported that pun1 1 was widely distributed among non-pungent C. annuum varieties, which is economically the most important domesticated species worldwide (Lee et al 2005). To date, three loss-of-function alleles of pun1 (pun1 1-3 ) have been identified in Capsicum (Stewart et al 2005(Stewart et al , 2007Stellari et al 2010;Wyatt et al 2012). In spite of the qualitative effects of Pun1 on pungency, the content of capsaicinoids has been controlled by quantitative trait loci (QTLs) (Blum et al 2003;Ben-Chaim et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Multiple loss-of-function putative aminotransferase alleles contribute to low pungency and capsinoid biosynthesis in Capsicum chinense

et al. 2015

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Capsicum chinense is a domesticated hot pepper species in the Capsicum genus that originated in the Amazon and is consumed in USA, the Caribbean and South America. Although a characteristic of this species is high pungency, some non-pungent or lowpungent strains, called ''Aji Dulce'' (sweet pepper in Spanish), exist in the Caribbean region. In the present study, low-pungent C. chinense accessions were analyzed in order to elucidate the genetic mechanisms responsible for low pungency. All low-pungent C. chinense accessions in this study carried non-functional alleles of putative aminotransferase (pAMT), which catalyzes the formation of vanillylamine from vanillin in the capsaicinoid biosynthetic pathway. These low-pungent accessions produced capsinoids, low-pungent capsaicinoid analogs. The pamt mutation in each strain was characterized using allele-specific markers, and one novel pamt allele (pamt 7 ) was identified. The pamt 7 had a new hAT family transposon insertion in the second exon region, which caused the loss of pAMT expression. pamt 7 is apparently an ancestral allele for pamt 6 because the 7-bp insertion in pamt 6 can be regarded as a footprint of the transposon. A phylogenetic analysis of pamt alleles was performed to examine their relationships. Combined with previously reported pamt alleles, the Tcc family transposon insertion and its excision were involved in the generation of various pamt alleles in C. chinense. A phylogenetic analysis of pamt alleles showed that at least five occurred within C. chinense after speciation of the Capsicum genus. In conclusion, the results of the present study identified pamt as the main and most frequent gene controlling low pungency in C. chinense. Allelic variations in loss-of function pamt and their wide distribution demonstrated the potential of C. chinense bioresources for genetic improvements to pungency and metabolic profiles in hot pepper breeding programs.

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Development and application of a suite of non-pungency markers for the Pun1 gene in pepper (Capsicum spp.)

Cited by 19 publications

References 8 publications

Non-pungency in a Japanese Chili Pepper Landrace (<i>Capsicum annuum</i>) is Caused by a Novel Loss-of-function <i>Pun1</i> Allele

Non-pungency in a Japanese Chili Pepper Landrace (<i>Capsicum annuum</i>) is Caused by a Novel Loss-of-function <i>Pun1</i> Allele

Positional differences of intronic transposons in pAMT affect the pungency level in chili pepper through altered splicing efficiency

Multiple loss-of-function putative aminotransferase alleles contribute to low pungency and capsinoid biosynthesis in Capsicum chinense

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