Kim Min-Jung, Kim Mirim, Lee Mi Rha, Park Soon Ki, Kim Jungmook
Department of Plant Biotechnology, Chonnam National University, Gwangju, 500-757, Korea.
Plant J. 2015 Mar;81(5):794-809. doi: 10.1111/tpj.12767.
During male gametophyte development in Arabidopsis thaliana, the microspores undergo an asymmetric division to produce a vegetative cell and a generative cell, which undergoes a second division to give rise to two sperm cells. SIDECAR POLLEN/LATERAL ORGAN BOUNDARIES DOMAIN (LBD) 27 plays a key role in the asymmetric division of microspores. Here we provide molecular genetic evidence that a combinatorial role of LBD10 with LBD27 is crucial for male gametophyte development in Arabidopsis. Expression analysis, genetic transmission and pollen viability assays, and pollen development analysis demonstrated that LBD10 plays a role in the male gametophyte function primarily at germ cell mitosis. In the mature pollen of lbd10 and lbd10 expressing a dominant negative version of LBD10, LBD10:SRDX, aberrant microspores such as bicellular and smaller tricellular pollen appeared at a ratio of 10-15% with a correspondingly decreased ratio of normal tricellular pollen, whereas in lbd27 mutants, 70% of the pollen was aborted. All pollen in the lbd10 lbd27 double mutants was aborted and severely shrivelled compared with that of the single mutants, indicating that LBD10 and LBD27 are essential for pollen development. Gene expression and subcellular localization analyses of LBD10:GFP and LBD27:RFP during pollen development indicated that posttranscriptional and/or posttranslational controls are involved in differential accumulation and subcellular localization of LBD10 and LBD27 during pollen development, which may contribute in part to combinatorial and distinct roles of LBD10 with LBD27 in microspore development. In addition, we showed that LBD10 and LBD27 interact to form a heterodimer for nuclear localization.
在拟南芥雄配子体发育过程中，小孢子进行不对称分裂产生一个营养细胞和一个生殖细胞，生殖细胞再进行一次分裂产生两个精细胞。侧车花粉/侧生器官边界结构域（LBD）27在小孢子的不对称分裂中起关键作用。在此，我们提供分子遗传学证据表明，LBD10与LBD27的组合作用对拟南芥雄配子体发育至关重要。表达分析、遗传传递和花粉活力测定以及花粉发育分析表明，LBD10主要在生殖细胞有丝分裂时对雄配子体功能起作用。在lbd10以及表达显性负性形式LBD10（LBD10:SRDX）的lbd10成熟花粉中，出现了异常小孢子，如双细胞和较小的三细胞花粉，比例为10%-15%，正常三细胞花粉的比例相应降低，而在lbd27突变体中，70%的花粉败育。与单突变体相比，lbd10 lbd27双突变体中的所有花粉均败育且严重皱缩，这表明LBD10和LBD27对花粉发育至关重要。花粉发育过程中LBD10:GFP和LBD27:RFP的基因表达和亚细胞定位分析表明，转录后和/或翻译后调控参与了花粉发育过程中LBD10和LBD27的差异积累和亚细胞定位，这可能部分有助于LBD10与LBD27在小孢子发育中的组合和不同作用。此外，我们还表明LBD10和LBD27相互作用形成异源二聚体进行核定位。
