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MUN ( MERISTEM UNSTRUCTURED ), encoding a SPC24 homolog of NDC80 kinetochore complex, affects development through cell division in Arabidopsis thaliana
Author(s) -
Shin Jinwoo,
Jeong Goowon,
Park JongYoon,
Kim Hoyeun,
Lee Ilha
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13823
Subject(s) - kinetochore , biology , centromere , chromosome segregation , arabidopsis , microbiology and biotechnology , genetics , cell division , mutant , chromosome , gene , cell
Summary Kinetochore, a protein super‐complex on the centromere of chromosomes, mediates chromosome segregation during cell division by providing attachment sites for spindle microtubules. The NDC 80 complex, composed of four proteins, NDC 80, NUF 2, SPC 24 and SPC 25, is localized at the outer kinetochore and connects spindle fibers to the kinetochore. Although it is conserved across species, functional studies of this complex are rare in Arabidopsis. Here, we characterize a recessive mutant, meristem unstructured‐1 ( mun‐1 ), exhibiting an abnormal phenotype with unstructured shoot apical meristem caused by ectopic expression of the WUSCHEL gene in unexpected tissues. mun‐1 is a weak allele because of the insertion of T‐ DNA in the promoter region of the SPC 24 homolog. The mutant exhibits stunted growth, embryo arrest, DNA aneuploidy, and defects in chromosome segregation with a low cell division rate. Null mutants of MUN from TALEN and CRISPR /Cas9‐mediated mutagenesis showed zygotic embryonic lethality similar to nuf2‐1 ; however, the null mutations were fully transmissible via pollen and ovules. Interactions among the components of the NDC 80 complex were confirmed in a yeast two‐hybrid assay and in planta co‐immunoprecipitation. MUN is co‐localized at the centromere with HTR 12/ CENH 3, which is a centromere‐specific histone variant, but MUN is not required to recruit HTR 12/ CENH 3 to the kinetochore. Our results support that MUN is a functional homolog of SPC 24 in Arabidopsis, which is required for proper cell division. In addition, we report the ectopic generations of stem cell niches by the malfunction of kinetochore components.