Tetrad pollen formation in quartet mutants of Arabidopsis thaliana is associated with persistence of pectic polysaccharides of the pollen mother cell wall
Tetrad pollen formation in quartet mutants of Arabidopsis thaliana is associated with persistence of pectic polysaccharides of the pollen mother cell wall
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DOI：
10.1046/j.1365-313x.1998.00183.x
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发表时间：
1998-07-01
期刊：
影响因子：
7.2
通讯作者：
Somerville, CR
中科院分区：
文献类型：
--
作者：
Rhee, SY;Somerville, CR
拟南芥的四联体（qrt）突变体产生四分体花粉，其中小孢子在花粉发育过程中不能分离。由于胼胝质沉积量之间的小孢子是与四分体花粉形成在其他物种，因为果胶是牵连发挥作用的细胞粘附，这些细胞壁成分在野生型和突变体花药可视化免疫荧光显微镜在不同阶段的小孢子发生。在野生型中，在减数分裂开始时在花粉母细胞周围和四分体时期在小孢子周围检测到胼胝质。小孢子在胼胝质消失时释放到药室内。在四分体花粉形成过程中，qrt1和qrt2突变体中胼胝质的沉积和降解与野生型没有区别。在四分体阶段从野生型小孢子中酶促去除胼胝质没有释放小孢子，表明胼胝质去除不足以分散野生型中的小孢子。在花粉母细胞的初生壁中检测到果胶成分。在四分体时期，该壁围绕着花粉母细胞和小孢子周围的胼胝质壁。在野生型，果胶成分的这一壁不再检测到在小孢子释放的时间。然而，在qrt1和qrt2突变体，果胶成分的这壁坚持胼胝质降解后。这一结果表明，在花粉母细胞壁中果胶降解的失败与qrt突变体中四分体花粉的形成有关，并表明QRT 1和ORT2可能是细胞类型特异性果胶降解分离小孢子所必需的。
The quartet (qrt) mutants of Arabidopsis thaliana produce tetrad pollen in which microspores fail to separate during pollen development. Because the amount of callose deposition between microspores is correlated with tetrad pollen formation in other species, and because pectin is implicated as playing a role in cell adhesion, these cell-wall components in wild-type and mutant anthers were visualized by immunofluorescence microscopy at different stages of microsporogenesis. In wild-type, callose was detected around the pollen mother cell at the onset of meiosis and around the microspores during the tetrad stage. Microspores were released into the anther locule at the stage where callose was no longer detected. Deposition and degradation of callose during tetrad pollen formation in qrt1 and qrt2 mutants were indistinguishable from those in wild-type. Enzymatic removal of callose from wild-type microspores at the tetrad stage did not release the microspores, suggesting that callose removal is not sufficient to disperse the microspores in wild-type. Pectic components were detected in the primary wall of the pollen mother cell. This wall surrounded the callosic wall around the pollen mother cell and the microspores during the tetrad stage. In wild-type, pectic components of this wall were no longer detectable at the time of microspore release. However, in qrt1 and qrt2 mutants, pectic components of this wall persisted after callose degradation. This result suggests that failure of pectin degradation in the pollen mother cell wall is associated with tetrad pollen formation in qrt mutants, and indicates that QRT1 and ORT2 may be required for cell type-specific pectin degradation to separate microspores.