title: Comparative Analysis of Fruit Metabolites and Pungency Candidate Genes Expression between Bhut Jolokia and Other Capsicum Species.
abstract: Bhut jolokia, commonly known as Ghost chili, a native Capsicum species found in North East India was recorded as the naturally occurring hottest chili in the world by the Guinness Book of World Records in 2006. Although few studies have reported variation in pungency content of this particular species, no study till date has reported detailed expression analysis of candidate genes involved in capsaicinoids (pungency) biosynthesis pathway and other fruit metabolites. Therefore, the present study was designed to evaluate the diversity of fruit morphology, fruiting habit, capsaicinoids and other metabolite contents in 136 different genotypes mainly collected from North East India. Significant intra and inter-specific variations for fruit morphological traits, fruiting habits and 65 fruit metabolites were observed in the collected Capsicum germplasm belonging to three Capsicum species i.e., Capsicum chinense (Bhut jolokia, 63 accessions), C. frutescens (17 accessions) and C. annuum (56 accessions). The pungency level, measured in Scoville Heat Unit (SHU) and antioxidant activity measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay showed maximum levels in C. chinense accessions followed by C. frutescens accessions, while C. annuum accessions showed the lowest value for both the traits. The number of different fruit metabolites detected did not vary significantly among the different species but the metabolite such as benzoic acid hydroxyl esters identified in large percentage in majority of C. annuum genotypes was totally absent in the C. chinense genotypes and sparingly present in few genotypes of C. frutescens. Significant correlations were observed between fruit metabolites capsaicin, dihydrocapsaicin, hexadecanoic acid, cyclopentane, α-tocopherol and antioxidant activity. Furthermore, comparative expression analysis (through qRT-PCR) of candidate genes involved in capsaicinoid biosynthesis pathway revealed many fold higher expression of majority of the genes in C. chinense compared to C. frutescens and C. annuum suggesting that the possible reason for extremely high pungency might be due to the higher level of candidate gene(s) expression although nucleotide variation in pungency related genes may also be involved in imparting variations in level of pungency.
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Sarpras
authors.initials: S
authors.lastname: M
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Rashmi
authors.initials: R
authors.lastname: Gaur
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Vineet
authors.initials: V
authors.lastname: Sharma
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Sushil Satish
authors.initials: SS
authors.lastname: Chhapekar
authors.affiliation: Department of Biological Science, Gauhati University, Guwahati, Assam, India.
authors.forename: Jharna
authors.initials: J
authors.lastname: Das
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.|Department of Plant Science, School of Biological Sciences, Central University of Kerala, Periya, Kasaragod, Kerala, India.
authors.forename: Ajay
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Centre for Genetic Manipulation of Crop Plants, University of Delhi South Campus, Benito Juarez Road, New Delhi, India.
authors.forename: Satish Kumar
authors.initials: SK
authors.lastname: Yadava
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Nitin
authors.affiliation: School of Computational and Integrative Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Vijaya
authors.initials: V
authors.lastname: Brahma
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Suresh K
authors.initials: SK
authors.lastname: Abraham
authors.affiliation: Translational and Evolutionary Genomics Lab, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Nirala
authors.initials: N
authors.lastname: Ramchiary
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D002211:Capsaicin / Q000031:analogs & derivatives / Q000032:analysis / Q000378:metabolism*; D002212:Capsicum / Q000033:anatomy & histology / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005638:Fruit / Q000033:anatomy & histology / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D007194:India
chemical_list: D000975:Antioxidants; D002211:Capsaicin