Resolvase OsGEN1 Mediates DNA Repair by Homologous Recombination

Abstract

Yen1/GEN1 are canonical Holliday junction resolvases that belong to the RAD2/XPG family. In eukaryotes, such as budding yeast, mice, worms, and humans, Yen1/GEN1 work together with Mus81-Mms4/MUS81-EME1 and Slx1-Slx4/SLX1-SLX4 in DNA repair by homologous recombination to maintain genome stability. In plants, the biological function of Yen1/GEN1 remains largely unclear. In this study, we characterized the loss of function mutants of OsGEN1 and OsSEND1, a pair of paralogs of Yen1/GEN1 in rice (Oryza sativa). We first investigated the role of OsGEN1 during meiosis and found a reduction in chiasma frequency by ;6% in osgen1 mutants, compared to the wild type, suggesting a possible involvement of OsGEN1 in the formation of crossovers. Postmeiosis, OsGEN1 foci were detected in wild-type microspore nuclei, but not in the osgen1 mutant concomitant with an increase in double-strand breaks. Persistent double-strand breaks led to programmed cell death of the male gametes and complete male sterility. In contrast, depletion of OsSEND1 had no effects on plant development and did not enhance osgen1 defects. Our results indicate that OsGEN1 is essential for homologous recombinational DNA repair at two stages of microsporogenesis in rice.

A Multiprotein Complex Regulates Interference-Sensitive Crossover Formation in Rice

“…The residual chiasmata in osshoc1-2 were randomly distributed, indicating that OsSHOC1 is involved in the formation of class I COs. Consistently, a further decrease in the number of COs was observed in the double mutant of OsSHOC1 and OsGEN1, the latter of which encodes a resolvase required for class II CO formation (Wang et al, 2017).…”

“…The hypothesized upstream function of OsSHOC1 in rice CO formation in relation to other ZMM proteins was investigated by genetic analysis. The mean chiasma frequency in oshei10 (6.06 6 2.86, n 5 167), as determined by Wang et al (2017), was much higher than that in osshoc1-2 (3.40 6 1.89, n 5 142) or osptd-1 (3.12 6 1.76, n 5 113). Moreover, the mean chiasma frequency in osshoc1-2 oshei10 double mutants (3.36 6 1.90, n 5 94) was similar to that in osshoc1-2, osptd-1, and osshoc1-2 osptd-1 (Table 1).…”

“…OsGEN1 is considered to function in the interferenceinsensitive CO pathway in rice (Wang et al, 2017). A significant reduction in the chiasma frequency was detected in the osshoc1-2 osgen1 double mutant (2.43 6 1.71, n 5 117) compared with that in the osshoc1-2 single mutant (3.40 6 1.89, n 5 142), and the distribution of residual chiasmata in osshoc1-2 osgen1 was consistent with a Poisson distribution (Kolmogorov-Smirnov test, P .…”

“…By highthroughput sequencing, an 11-bp deletion was detected within the coding region of LOC_Os02g42910. osgen1 and oshei10 were described previously (Wang et al, 2017). Four double mutants, osshoc1-2 oshei10, osshoc1-2 oszip4, osshoc1-2 osptd-1, and osshoc1-2 osgen1, were generated by crossing heterozygous plants of osshoc1-2 with the other heterozygous plants, respectively, and were identified from F2 populations.…”

Genome editing in wheat microspores and haploid embryos mediated by delivery of ZFN proteins and cell‐penetrating peptide complexes

“…There are a scarce number of reports indicating the preferred DNA repair pathway (non‐homologous end joining versus homologous recombination) in uninucleate microspores. It has been shown that the cells are sensitive to mutation of OsGEN1 gene involved in homologous recombination DNA repair in rice and initiate programmed cell death during the first asymmetric mitotic division (Wang et al , ). This can potentially suggest that the HR pathway is essential for male gametogenesis and microspores possess an active DNA repair mechanism.…”