Chen Xiong-Yan, Liu Lin, Lee Eunkyoung, Han Xiao, Rim Yeonggil, Chu Hyosub, Kim Seon-Won, Sack Fred, Kim Jae-Yean
Division of Applied Life Science (BK21 Program), Graduate School of Gyeongsang National University, Plant Molecular Biology and Biotechnology Research Center, Environmental Biotechnology National Core Research Center, Jinju 660-701, Korea.
Plant Physiol. 2009 May;150(1):105-13. doi: 10.1104/pp.108.133918. Epub 2009 Mar 13.
Cytokinesis is the division of the cytoplasm and its separation into two daughter cells. Cell plate growth and cytokinesis appear to require callose, but direct functional evidence is still lacking. To determine the role of callose and its synthesis during cytokinesis, we identified and characterized mutants in many members of the GLUCAN SYNTHASE-LIKE (GSL; or CALLOSE SYNTHASE) gene family in Arabidopsis (Arabidopsis thaliana). Most gsl mutants (gsl1-gsl7, gsl9, gsl11, and gsl12) exhibited roughly normal seedling growth and development. However, mutations in GSL8, which were previously reported to be gametophytic lethal, were found to produce seedlings with pleiotropic defects during embryogenesis and early vegetative growth. We found cell wall stubs, two nuclei in one cell, and other defects in cell division in homozygous gsl8 insertional alleles. In addition, gsl8 mutants and inducible RNA interference lines of GSL8 showed reduced callose deposition at cell plates and/or new cell walls. Together, these data show that the GSL8 gene encodes a putative callose synthase required for cytokinesis and seedling maturation. In addition, gsl8 mutants disrupt cellular and tissue-level patterning, as shown by the presence of clusters of stomata in direct contact and by islands of excessive cell proliferation in the developing epidermis. Thus, GSL8 is required for patterning as well as cytokinesis during Arabidopsis development.
胞质分裂是细胞质的分裂并将其分离成两个子细胞的过程。细胞板生长和胞质分裂似乎需要胼胝质，但仍缺乏直接的功能证据。为了确定胼胝质及其合成在胞质分裂过程中的作用，我们鉴定并表征了拟南芥中葡聚糖合酶样（GSL；或胼胝质合酶）基因家族许多成员的突变体。大多数gsl突变体（gsl1 - gsl7、gsl9、gsl11和gsl12）表现出大致正常的幼苗生长和发育。然而，之前报道为配子体致死的GSL8突变体被发现会产生在胚胎发生和早期营养生长期间具有多效性缺陷的幼苗。我们在纯合gsl8插入等位基因中发现了细胞壁残端、一个细胞中有两个细胞核以及细胞分裂中的其他缺陷。此外，gsl8突变体和GSL8的诱导型RNA干扰株系在细胞板和/或新细胞壁处的胼胝质沉积减少。这些数据共同表明，GSL8基因编码一种胞质分裂和幼苗成熟所需的假定胼胝质合酶。此外，gsl8突变体破坏了细胞和组织水平的模式形成，如发育中的表皮中存在直接接触的气孔簇以及过度细胞增殖的岛状区域所示。因此，在拟南芥发育过程中，GSL8对于模式形成以及胞质分裂都是必需的。
