title: Introgressing Subgenome Components fromBrassica rapaandB. carinatatoB. junceafor Broadening Its Genetic Base and Exploring Intersubgenomic Heterosis.
abstract: Brassica juncea(AjAjBjBj), is an allotetraploid that arose from two diploid species,B. rapa(ArAr) andB. nigra(BnBn). It is an old oilseed crop with unique favorable traits, but the genetic improvement on this species is limited. We developed an approach to broaden its genetic base within several generations by intensive selection. The Arsubgenome from the Asian oil cropB. rapa(ArAr) and the Bcsubgenome from the African oil cropB. carinata(BcBcCcCc) were combined in a synthesized allohexaploid (ArArBcBcCcCc), which was crossed with traditionalB. junceato generate pentaploid F1hybrids (ArAjBcBjCc), with subsequent self-pollination to obtain newly synthesizedB. juncea(Ar/jAr/jBc/jBc/j). After intensive cytological screening and phenotypic selection of fertility and agronomic traits, a population of new-typeB. junceawas obtained and was found to be genetically stable at the F6generation. The new-typeB. junceapossesses good fertility and rich genetic diversity and is distinctly divergent but not isolated from traditionalB. juncea, as revealed by population genetic analysis with molecular markers. More than half of its genome was modified, showing exotic introgression and novel variation. In addition to the improvement in some traits of the new-typeB. juncealines, a considerable potential for heterosis was observed in inter-subgenomic hybrids between new-typeB. juncealines and traditionalB. junceaaccessions. The new-typeB. junceaexhibited a stable chromosome number and a novel genome composition through multiple generations, providing insight into how to significantly broaden the genetic base of crops with subgenome introgression from their related species and the potential of exploring inter-subgenomic heterosis for hybrid breeding.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Zili
authors.initials: Z
authors.lastname: Wei
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Shihao
authors.initials: S
authors.lastname: Chang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wu
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Peifa
authors.initials: P
authors.lastname: Liu
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Jinling
authors.initials: J
authors.lastname: Meng
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, College of Plant Science & Technology, Huazhong Agricultural University Wuhan, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
keywords: Brassica juncea; Development of new-type Brassica juncea with introgression of subgenomes from related oilseed species.; genetic diversity; heterosis; interspecific hybridization; novel population; subgenomic introgression