Plant & Animal Genomes XVI Conference

January 12-16, 2008
Town & Country Convention Center
San Diego, CA

QTL Analysis Of Isothiocyanate Content In A Brassica Interspecific Hybrid

Dan Qiu¹ , Muqiang Gao² , Cori Ellison³ , Genyi Li⁴ , Fenglian Huang¹ , J. Erron Haggard¹ , Florence Negre-Zakharov¹ , Ferdinando Branca⁵ , Carlos Quiros¹

¹  Department of Plant Sciences, University of California, Davis, CA 95616

²  Department of Agronomy, University of Kentucky, Lexington, KY 40546

³  Div. of Plant Biology, University of California, Davis, CA 95616

⁴  Department of Plant Science, University of Manitoba, Winnipeg Manitoba, Canada R3T 2N2

⁵  DOFATA, Universita de Catania, Catania, Italy

We used for this study an F2 population of 160 plants constructed by crossing doubled haploid broccoli DH ‘Early Big’ (B. oleracea) and its related wild species B. macrocarpa. The wild species produces high amounts of the aliphatic glucosinolate (GSL) sinigrin and upon hydrolysis it yields high amounts of allyl isothiocyanate. The broccoli parent produces mostly the aliphatic GSL glucoraphanin, which is hydrolyzed in small amounts to the isothiocyanate (ITC) sulforaphane. This compound has been involved in cancer protection in mammals. The long term objective of this project is to recombine the genes of both parents to produce broccoli lines with high sulforaphane content. We constructed a linkage map containing 53 SSR, 94 SRAP markers and 10 major Brassica genes involved in the GSL pathway and their hydrolysis products, which include BoCS-lyase, BoGS-OH, BoCYP79F1, BoS-GT, BoGSL-ALK, BoGSL-ELONG, BoGSL-PRO, Bo-CYP83A1, Bo-ESP and Bo-ESM1. This genetic map has 157 markers arranged in 9 linkage groups covering 653 cM. QTL analysis for GSL and ITC content was performed in the mapping population. The genes BoGS-OH, BoGSL-ALK, BoGSL-ELONG and BoGSL-PRO fell into QTL regions associated to specific aliphatic GSL compounds in general agreement with their assigned function . Of the two genes reported to control GSL hydrolysis into ITC , namely Bo-ESP and Bo-ESM1, only the latter fell into two QTL (LOD>3.0). These QTL associated to presence of sulforaphane were on linkage groups O5 and O7. The genes in this pathway display a significant net of interactions revealing a complex relationship of different QTL for aliphatic GSL biosynthesis and hydrolysis and ITC. However, it was possible to advance lines from this interspecific population with high content of sulforaphane or allyl ITC, surpassing the amounts of these compounds normally observed in Brassica crops.