Fertile allohexaploid Brassica hybrids obtained from crosses between B. oleracea and B. juncea via ovule rescue and colchicine treatment of cuttings

Margaret W. Mwathi, Mehak Gupta, Daniela Quezada-Martinez, Aneeta Pradhan, Jacqueline Batley, Annaliese S. Mason

Research output: Contribution to journalArticle

Abstract

An allohexaploid Brassica crop (2n = AABBCC) does not exist naturally, but is of interest for its potential to combine useful traits found in the six cultivated Brassica species which share combinations of the A, B and C genomes with additional allelic heterosis. In this study, we aimed to produce 2n = AABBCC hybrids by crosses between B. juncea and a number of Brassica C genome species. We used ovule rescue to overcome hybridization barriers and different colchicine treatment methods to induce chromosome doubling of ABC hybrids to AABBCC allohexaploids, thus restoring fertility. Only the cross B. oleracea × B. juncea was successful, with six triploid hybrids produced from one genotype combination. Colchicine-containing regeneration media was unsuccessful in doubling chromosome number in these hybrids, but treatment of cuttings with 0.05 to 0.25% colchicine successfully produced ~ 200 S1 allohexaploid seeds. The S1 plants produced 7–84% viable pollen and set 0–390 seeds per plant, with 23–27 bivalents and 0–3 univalents during metaphase I of meiosis. Our results highlight the difficulties in working with the wild C genome species, but showed that our methods have utility for producing euploid, chromosome-doubled progeny in this cross combination. Further, Brassica oleracea × B. juncea allohexaploid hybrids may contain useful genetic factors for improved meiotic stability and fertility in allohexaploid germplasm pools.

Original languageEnglish
JournalPlant Cell, Tissue and Organ Culture
DOIs
Publication statusE-pub ahead of print - 2 Nov 2019

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colchicine
Brassica juncea
Brassica oleracea
Brassica
ovules
genome
chromosomes
cole crops
triploidy
seed set
heterosis
metaphase
meiosis
chromosome number
germplasm
hybridization
pollen
genotype
seeds
methodology

Cite this

@article{8664ed970e7e4c408244245cef39e6e5,
title = "Fertile allohexaploid Brassica hybrids obtained from crosses between B. oleracea and B. juncea via ovule rescue and colchicine treatment of cuttings",
abstract = "An allohexaploid Brassica crop (2n = AABBCC) does not exist naturally, but is of interest for its potential to combine useful traits found in the six cultivated Brassica species which share combinations of the A, B and C genomes with additional allelic heterosis. In this study, we aimed to produce 2n = AABBCC hybrids by crosses between B. juncea and a number of Brassica C genome species. We used ovule rescue to overcome hybridization barriers and different colchicine treatment methods to induce chromosome doubling of ABC hybrids to AABBCC allohexaploids, thus restoring fertility. Only the cross B. oleracea × B. juncea was successful, with six triploid hybrids produced from one genotype combination. Colchicine-containing regeneration media was unsuccessful in doubling chromosome number in these hybrids, but treatment of cuttings with 0.05 to 0.25{\%} colchicine successfully produced ~ 200 S1 allohexaploid seeds. The S1 plants produced 7–84{\%} viable pollen and set 0–390 seeds per plant, with 23–27 bivalents and 0–3 univalents during metaphase I of meiosis. Our results highlight the difficulties in working with the wild C genome species, but showed that our methods have utility for producing euploid, chromosome-doubled progeny in this cross combination. Further, Brassica oleracea × B. juncea allohexaploid hybrids may contain useful genetic factors for improved meiotic stability and fertility in allohexaploid germplasm pools.",
keywords = "Allohexaploid, Brassica, Chromosome doubling, Colchicine, Interspecific hybridization, Ovule culture",
author = "Mwathi, {Margaret W.} and Mehak Gupta and Daniela Quezada-Martinez and Aneeta Pradhan and Jacqueline Batley and Mason, {Annaliese S.}",
year = "2019",
month = "11",
day = "2",
doi = "10.1007/s11240-019-01728-x",
language = "English",
journal = "Plant Cell, Tissue and Organ Culture",
issn = "0167-6857",
publisher = "Springer",

}

Fertile allohexaploid Brassica hybrids obtained from crosses between B. oleracea and B. juncea via ovule rescue and colchicine treatment of cuttings. / Mwathi, Margaret W.; Gupta, Mehak; Quezada-Martinez, Daniela; Pradhan, Aneeta; Batley, Jacqueline; Mason, Annaliese S.

In: Plant Cell, Tissue and Organ Culture, 02.11.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Fertile allohexaploid Brassica hybrids obtained from crosses between B. oleracea and B. juncea via ovule rescue and colchicine treatment of cuttings

AU - Mwathi, Margaret W.

AU - Gupta, Mehak

AU - Quezada-Martinez, Daniela

AU - Pradhan, Aneeta

AU - Batley, Jacqueline

AU - Mason, Annaliese S.

PY - 2019/11/2

Y1 - 2019/11/2

N2 - An allohexaploid Brassica crop (2n = AABBCC) does not exist naturally, but is of interest for its potential to combine useful traits found in the six cultivated Brassica species which share combinations of the A, B and C genomes with additional allelic heterosis. In this study, we aimed to produce 2n = AABBCC hybrids by crosses between B. juncea and a number of Brassica C genome species. We used ovule rescue to overcome hybridization barriers and different colchicine treatment methods to induce chromosome doubling of ABC hybrids to AABBCC allohexaploids, thus restoring fertility. Only the cross B. oleracea × B. juncea was successful, with six triploid hybrids produced from one genotype combination. Colchicine-containing regeneration media was unsuccessful in doubling chromosome number in these hybrids, but treatment of cuttings with 0.05 to 0.25% colchicine successfully produced ~ 200 S1 allohexaploid seeds. The S1 plants produced 7–84% viable pollen and set 0–390 seeds per plant, with 23–27 bivalents and 0–3 univalents during metaphase I of meiosis. Our results highlight the difficulties in working with the wild C genome species, but showed that our methods have utility for producing euploid, chromosome-doubled progeny in this cross combination. Further, Brassica oleracea × B. juncea allohexaploid hybrids may contain useful genetic factors for improved meiotic stability and fertility in allohexaploid germplasm pools.

AB - An allohexaploid Brassica crop (2n = AABBCC) does not exist naturally, but is of interest for its potential to combine useful traits found in the six cultivated Brassica species which share combinations of the A, B and C genomes with additional allelic heterosis. In this study, we aimed to produce 2n = AABBCC hybrids by crosses between B. juncea and a number of Brassica C genome species. We used ovule rescue to overcome hybridization barriers and different colchicine treatment methods to induce chromosome doubling of ABC hybrids to AABBCC allohexaploids, thus restoring fertility. Only the cross B. oleracea × B. juncea was successful, with six triploid hybrids produced from one genotype combination. Colchicine-containing regeneration media was unsuccessful in doubling chromosome number in these hybrids, but treatment of cuttings with 0.05 to 0.25% colchicine successfully produced ~ 200 S1 allohexaploid seeds. The S1 plants produced 7–84% viable pollen and set 0–390 seeds per plant, with 23–27 bivalents and 0–3 univalents during metaphase I of meiosis. Our results highlight the difficulties in working with the wild C genome species, but showed that our methods have utility for producing euploid, chromosome-doubled progeny in this cross combination. Further, Brassica oleracea × B. juncea allohexaploid hybrids may contain useful genetic factors for improved meiotic stability and fertility in allohexaploid germplasm pools.

KW - Allohexaploid

KW - Brassica

KW - Chromosome doubling

KW - Colchicine

KW - Interspecific hybridization

KW - Ovule culture

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U2 - 10.1007/s11240-019-01728-x

DO - 10.1007/s11240-019-01728-x

M3 - Article

JO - Plant Cell, Tissue and Organ Culture

JF - Plant Cell, Tissue and Organ Culture

SN - 0167-6857

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