The distinct functions of two classical arabinogalactan proteins BcMF8 and BcMF18 during pollen wall development in Brassica campestris
The distinct functions of two classical arabinogalactan proteins BcMF8 and BcMF18 during pollen wall development in Brassica campestris
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两种经典阿拉伯半乳聚糖蛋白 BcMF8 和 BcMF18 在油菜花粉壁发育过程中的不同功能
DOI：
10.1111/tpj.13842
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发表时间：
2018-04-01
期刊：
影响因子：
7.2
通讯作者：
Cao, Jiashu
中科院分区：
文献类型：
--
作者：
Lin, Sue;Yue, Xiaoyan;Cao, Jiashu
阿拉伯半乳聚糖蛋白（AGPs）是广泛糖基化的富含羟脯氨酸的糖蛋白，广泛存在于所有植物组织和细胞中。AtAGP 6和AtAGP 11是拟南芥花粉特异性的经典AGP编码基因，在小孢子发育过程中具有冗余功能。从白菜中分离的BcMF 18和BcMF 8分别是AtAGP 6和AtAGP 11的直系同源物。与AtAGP 6和AtAGP 11的功能冗余相反，BcMF 8的单基因破坏导致B. campestris中具有异常内壁发育和异位孔形成的变形花粉粒。在此，我们进一步探讨了BcMF 18的作用及其与BcMF 8的关系。BcMF 18在小孢子发育后期的花粉中特异表达。BcMF 18基因缺失的反义RNA转基因株系，花粉粒纤维素分布异常，缺乏内壁、细胞质和细胞核。具有BcMF 8和BcMF 18两者的抑制性表达的转基因植物显示杂交表型，表达单基因敲除植物系的表型的混合物。此外，我们确定了BcMF 18/BcMF 8和AtAGP 6/AtAGP 11之间的功能多样性，主要体现在BcMF 18和BcMF 8对花粉壁形成的特定贡献。这些结果表明，与拟南芥中的AtAGP 6和AtAGP 11基因不同，BcMF 18和BcMF 8都参与了B.campestris花粉的生物发生，在小孢子发育过程中通过独立的途径发挥作用。我们的研究结果表明，与AtAGP 6和AtAGP 11在拟南芥中具有冗余功能不同，它们在油菜中的直系同源基因BcMF 18和BcMF 8都是花粉生物发生所必需的，在花粉壁发育过程中通过独立的途径发挥作用，这表明BcMF 8和BcMF 18在小孢子发育中发挥着重要且多样化的作用。
Arabinogalactan proteins (AGPs) are extensively glycosylated hydroxyproline-rich glycoproteins ubiquitous in all plant tissues and cells. AtAGP6 and AtAGP11, the only two functionally known pollen-specific classical AGP encoding genes in Arabidopsis, are reported to have redundant functions in microspore development. BcMF18 and BcMF8 isolated from Brassica campestris are the orthologues of AtAGP6 and AtAGP11, respectively. In contrast to the functional redundancy of AtAGP6 and AtAGP11, single-gene disruption of BcMF8 led to deformed pollen grains with abnormal intine development and ectopic aperture formation in B.campestris. Here, we further explored the action of BcMF18 and its relationship with BcMF8. BcMF18 was specifically expressed in pollen during the late stages of microspore development. Antisense RNA transgenic lines with BcMF18 reduction resulted in aberrant pollen grains with abnormal cellulose distribution, lacking intine, cytoplasm and nuclei. Transgenic plants with repressive expression of both BcMF8 and BcMF18 showed a hybrid phenotype, expressing a mixture of the phenotypes of the single gene knockdown plant lines. In addition, we identified functional diversity between BcMF18/BcMF8 and AtAGP6/AtAGP11, mainly reflected by the specific contribution of BcMF18 and BcMF8 to pollen wall formation. These results suggest that, unlike the orthologous genes AtAGP6 and AtAGP11 in Arabidopsis, BcMF18 and BcMF8 are both integral to pollen biogenesis in B.campestris, acting through independent pathways during microspore development.Significance Statement Arabinogalactan proteins (AGPs) are cell wall-associated glycoproteins which have been identified to be implicated in microspore development. The findings of our manuscript show that unlike AtAGP6 and AtAGP11 which have redundant functions in Arabidopsis, their orthologous genes BcMF18 and BcMF8 in Brassica campestris are both integral to pollen biogenesis, acting through independent pathways during pollen wall development, suggesting an essential and diversified role for BcMF8 and BcMF18 in microspore development.