期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：33
DOI：10.1073/pnas.2021970118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Meiotic recombination plays a fundamental role in shaping genetic diversity in eukaryotes. Extensive variation in crossover rate exists between populations and species. The identity of modifier loci and their roles in genome evolution remain incompletely understood. We explored natural variation in
Arabidopsis crossover and identified
SNI1 as the causal gene underlying a major modifier locus. To date, SNI1 had no known role in crossover. SNI1 is a component of the SMC5/6 complex that is closely related to cohesin and condensin.
Arabidopsis sni1 and other SMC5/6 mutants show similar effects on the interference-independent crossover pathway. Hence, our findings demonstrate that the SMC5/6 complex, which is known for its role in DNA damage repair, is also important for control of meiotic crossover.
The frequency and distribution of meiotic crossovers are tightly controlled; however, variation in this process can be observed both within and between species. Using crosses of two natural
Arabidopsis thaliana accessions, Col and L
er, we mapped a crossover modifier locus to semidominant polymorphisms in
SUPPRESSOR OF NPR1-1 INDUCIBLE 1 (
SNI1), which encodes a component of the SMC5/6 complex. The
sni1 mutant exhibits a modified pattern of recombination across the genome with crossovers elevated in chromosome distal regions but reduced in pericentromeres. Mutations in
SNI1 result in reduced crossover interference and can partially restore the fertility of a Class I crossover pathway mutant, which suggests that the protein affects noninterfering crossover repair. Therefore, we tested genetic interactions between SNI1 and both RECQ4 and FANCM DNA helicases, which showed that additional Class II crossovers observed in the
sni1 mutant are FANCM independent. Furthermore, genetic analysis of other SMC5/6 mutants confirms the observations of crossover redistribution made for
SNI1. The study reveals the importance of the SMC5/6 complex in ensuring the proper progress of meiotic recombination in plants.
