TY - JOUR
T1 - Meiotic chromosome axis remodelling is critical for meiotic recombination in Brassica rapa
AU - Cuacos, Maria
AU - Lambing, Christophe
AU - Pachon Penalba, Miguel
AU - Osman, Kim
AU - Armstrong, Susan
AU - Henderson, Ian
AU - Sanchez-Moran, Eugenio
AU - Franklin, Chris
AU - Heckmann, Stefan
PY - 2021/1/27
Y1 - 2021/1/27
N2 - Meiosis generates genetic variation through homologous recombination (HR) that is harnessed during breeding. HR occurs in the context of meiotic chromosome axes and the synaptonemal complex. To study the role of axis remodelling in crossover (CO) formation in a crop species, we characterized mutants of the axis-associated protein ASY1 and the axis-remodelling protein PCH2 in Brassica rapa. asy1 plants form meiotic chromosome axes that fail to synapse. CO formation is almost abolished, and residual chiasmata are proportionally enriched in terminal chromosome regions, particularly in the nucleolar organizing region (NOR)-carrying chromosome arm. pch2 plants show impaired ASY1 loading and remodelling, consequently achieving only partial synapsis, which leads to reduced CO formation and loss of the obligatory CO. PCH2-independent chiasmata are proportionally enriched towards distal chromosome regions. Similarly, in Arabidopsis pch2, COs are increased towards telomeric regions at the expense of (peri-) centromeric COs compared with the wild type. Taken together, in B. rapa, axis formation and remodelling are critical for meiotic fidelity including synapsis and CO formation, and in asy1 and pch2 CO distributions are altered. While asy1 plants are sterile, pch2 plants are semi-sterile and thus PCH2 could be an interesting target for breeding programmes.
AB - Meiosis generates genetic variation through homologous recombination (HR) that is harnessed during breeding. HR occurs in the context of meiotic chromosome axes and the synaptonemal complex. To study the role of axis remodelling in crossover (CO) formation in a crop species, we characterized mutants of the axis-associated protein ASY1 and the axis-remodelling protein PCH2 in Brassica rapa. asy1 plants form meiotic chromosome axes that fail to synapse. CO formation is almost abolished, and residual chiasmata are proportionally enriched in terminal chromosome regions, particularly in the nucleolar organizing region (NOR)-carrying chromosome arm. pch2 plants show impaired ASY1 loading and remodelling, consequently achieving only partial synapsis, which leads to reduced CO formation and loss of the obligatory CO. PCH2-independent chiasmata are proportionally enriched towards distal chromosome regions. Similarly, in Arabidopsis pch2, COs are increased towards telomeric regions at the expense of (peri-) centromeric COs compared with the wild type. Taken together, in B. rapa, axis formation and remodelling are critical for meiotic fidelity including synapsis and CO formation, and in asy1 and pch2 CO distributions are altered. While asy1 plants are sterile, pch2 plants are semi-sterile and thus PCH2 could be an interesting target for breeding programmes.
KW - ASY1
KW - Brassica rapa
KW - PCH2
KW - crossover
KW - meiosis
KW - meiotic chromosome axis remodelling
KW - meiotic recombination
KW - synaptonemal complex
UR - http://www.scopus.com/inward/record.url?scp=85105071725&partnerID=8YFLogxK
U2 - 10.1093/jxb/erab035
DO - 10.1093/jxb/erab035
M3 - Article
SN - 0022-0957
VL - 2021
SP - 3012
EP - 3027
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
IS - 00
M1 - erab035
ER -