Table 1.
Morphological characteristics of Capsicum fruits.
Fig 1.
Morphological diversity of Capsicum species.
Selected Capsicum germplasm from North East India showing contrasting phenotypes for fruit morphology, color, and fruiting habits. Accessions in 1-3rd rows are contrasting Bhut jolokia genotypes (C. chinense), 4th and 5th row contains C. chinense, C. frutescens and C. annuum accessions.
Fig 2.
SHU range of different Capsicum species.
Total capsaicinoids content observed in C. chinense (63 accessions), C. frutescens (17 accessions) and C. annuum (56 accessions) accessions in Scoville Heat Unit (SHU).
Fig 3.
Metabolite range of different Capsicum species.
Metabolite range of C. chinense, C. frutescens and C. annuum varieties.
Fig 4.
Range of antioxidant activity of different Capsicum species.
Anti-oxidant activity using DPPH assay obtained for C. chinense, C. frutescens and C. annuum varieties and represented in 25mg/ml dilutions.
Fig 5.
Principal component analysis of metabolites identified using gas chromatography–mass spectrometry (GC–MS) analysis.
For GC–MS, different genotypes of C. chinense [Acc 1–63 (major accession formed red circle)], C. frutescens [Acc 64–80 (major accession formed blue circle)] and C. annuum [Acc 81–136 (major accession formed brown circle)] were analysed and the correlation variances explained by the PC1 and PC2 components are 51% and 11%, respectively.
Table 2.
Pearson correlation co-efficient values observed between different metabolites on the basis of their peak intensities.
Fig 6.
Pungency and capsaicinoid biosynthesis gene expression analysis.
(A) Pungency analysis of selected Capsicum genotypes (B) Quantitative real time PCR analysis to analyze the expression of candidate genes involved in capsaicinoid biosynthesis pathway in highly pungent Bhut jolokia (Acc 23 and Acc 50), moderately pungent C. frutescens (Acc 65) and low pungent C. annuum (Acc 93 and Acc 95) accessions. The expression analysis was done in leaf, flowers, and three different stages of fruit developmental i.e. green (20 days after anthesis), Breaker (30–45 days after anthesis) and Mature stage of each genotype. The majority of the important genes involved in the capsaicinoid biosynthesis pathway (Pun 1, AMT, ACS, ACL, KAS and BCAT) were expressed very high in C. chinense accessions followed by C. frutescens. The low pungent C. annuum accessions showed very low expression of these genes. The other genes (PAL, COMT, FatA and C4H) were expressed variably among the three species. ***P<0.001