QTLmapping for capsaicin and dihydrocapsaicin content in a population ofCapsicum annuum‘NB1’ × Capsicum chinense‘Bhut Jolokia’

Abstract

AbstractCapsaicinoids are pungent compounds used for industrial and medical purposes including food, medicine and cosmetics. The Indian local variety ‘Bhut Jolokia’ (Capsicum chinenseJacq.) is one of the world's hottest chilli peppers. It produces more than one million Scoville heat units (SHUs) in total capsaicinoids. In this study, our goal was to identify quantitative trait loci (QTLs) responsible for the high content of capsaicin and dihydrocapsaicin in ‘Bhut Jolokia’.Capsicum annuum‘NB1’, a Korean pepper inbred line containing 14 000SHUs, was used as a maternal line. An F2population derived by crossing between ‘NB1’ and ‘Bhut Jolokia’ was generated to mapQTLs for capsaicinoids content. A total of 234 markers, including 201HRM, 21SSR, 2CAPSand 10 gene‐based markers of the capsaicinoid synthesis pathway, were mapped. The final map covered a total distance of 1175.2cMand contained 12 linkage groups corresponding to the basic chromosome number of chilli pepper. Capsaicin and dihydrocapsaicin content were analysed in 175 F2pepper fruits using theHPLCmethod. The maximum total capsaicinoids content was 1389 mg per 100g DW (dry weight), and the minimum content was 11 mg per 100g DW. TwoQTLs (qcap3.1andqcap6.1) for capsaicin content were identified onLG3 andLG6, and twoQTLs (qhdc2.1andqdhc2.2) for dihydrocapsaicin content were located onLG2. We did not detectQTLs for total capsaicinoids content. TheQTLpositions for capsaicin content were different from those for dihydrocapsaicin content. These results indicate that the complexity of selecting for more pungent chilli peppers must be considered in a chilli pepper breeding programme. TheQTL‐linked markers identified here will be helpful to develop more pungent pepper varieties from ‘Bhut Jolokia’, a very hot pepper.