Department of Biology, Pennsylvania State University, University Park, PA 16802, USA.
Mol Plant. 2008 Jul;1(4):645-58. doi: 10.1093/mp/ssn029. Epub 2008 Jun 3.
Mitogen-activated protein kinase (MAPK) and leucine-rich repeat receptor-like kinase (LRR-RLK) signaling pathways have been shown to regulate diverse aspects of plant growth and development. In Arabidopsis, proper anther development relies on intercellular communication to coordinate cell proliferation and differentiation. Two closely related genes encoding MAPKs, MPK3 and MPK6, function redundantly in regulating stomatal patterning. Although the mpk6 mutant has reduced fertility, the function of MPK3 and MPK6 in anther development has not been characterized. Similarly, the ERECTA (ER), ERECTA-LIKE1 (ERL1) and ERL2 genes encoding LRR-RLKs function together to direct stomatal cell fate specification and the er-105 erl1-2 erl2-1 triple mutant is sterile. Because the mpk3 mpk6 double null mutant is embryo lethal, anther development was characterized in the viable mpk3/+ mpk6/- and er-105 erl1-2 erl2-1 mutants. We found that both mutant anthers usually fail to form one or more of the four anther lobes, with the er-105 erl1-2 erl2-1 triple mutant exhibiting more severe phenotypes than those of the mpk3/+ mpk6/- mutant. The somatic cell layers of the differentiated mutant lobes appeared larger and more disorganized than that of wild-type. In addition, the er-105 erl1-2 erl2-1 triple mutant has a reduced number of stamens, the majority of which possess completely undifferentiated or under-differentiated anthers. Furthermore, sometimes, the mpk3/+ mpk6/- mutant anthers do not dehisce, and the er-105 erl1-2 erl2-1 anthers were not observed to dehisce. Therefore, our results indicate that both ER/ERL1/ERL2 and MPK3/MPK6 play important roles in normal anther lobe formation and anther cell differentiation. The close functional relationship between these genes in other developmental processes and the similarities in anther developmental phenotypes of the two types of mutants reported here further suggest the possibility that these genes might also function in the same pathway to regulate anther cell division and differentiation.
丝裂原活化蛋白激酶 (MAPK) 和富含亮氨酸重复受体样激酶 (LRR-RLK) 信号通路已被证明可调节植物生长和发育的各个方面。在拟南芥中，适当的花药发育依赖于细胞间通讯来协调细胞增殖和分化。两个密切相关的基因编码 MAPK，MPK3 和 MPK6，在调节气孔模式形成中具有冗余功能。尽管 mpk6 突变体的育性降低，但 MPK3 和 MPK6 在花药发育中的功能尚未得到表征。同样，编码 LRR-RLK 的 ERECTA (ER)、 ERECTA-LIKE1 (ERL1) 和 ERL2 基因共同作用以指导气孔细胞命运特化，而 er-105 erl1-2 erl2-1 三突变体是不育的。由于 mpk3 mpk6 双缺失突变体是胚胎致死的，因此在存活的 mpk3/+ mpk6/-和 er-105 erl1-2 erl2-1 突变体中对花药发育进行了表征。我们发现，这两种突变体的花药通常不能形成一个或多个四个花药裂片，而 er-105 erl1-2 erl2-1 三突变体的表型比 mpk3/+ mpk6/-突变体更严重。分化突变裂片的体细胞层比野生型更大且更紊乱。此外，er-105 erl1-2 erl2-1 三突变体的雄蕊数量减少，其中大多数具有完全未分化或未充分分化的花药。此外，有时，mpk3/+ mpk6/-突变体的花药不裂开，而 er-105 erl1-2 erl2-1 的花药则未观察到裂开。因此，我们的结果表明，ER/ERL1/ERL2 和 MPK3/MPK6 都在正常花药裂片形成和花药细胞分化中发挥重要作用。这些基因在其他发育过程中的密切功能关系以及这两种类型突变体在花药发育表型上的相似性进一步表明，这些基因也可能在同一途径中发挥作用，以调节花药细胞分裂和分化。
