Pollen tubes of Nicotiana alata express two genes from different β-glucan synthase families
Pollen tubes of Nicotiana alata express two genes from different β-glucan synthase families
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DOI：
10.1104/pp.125.4.2040
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发表时间：
2001-04-01
期刊：
影响因子：
7.4
通讯作者：
Read, SM
中科院分区：
文献类型：
--
作者：
Doblin, MS;De Melis, L;Read, SM
生长的花粉管沉积的壁含有两种类型的p -葡聚糖，(1,3)- β -葡聚糖胼胝质和(1,4)- β -葡聚糖纤维素，以及各种a-连接的果胶多糖。因此，我们利用观赏烟草Nicotiana alata Link et Otto的花粉管来鉴定可能编码胼胝质合成酶和纤维素合成酶催化亚基的基因。利用花粉管RNA和设计用于细菌和植物纤维素合酶（CesA）基因保守区域的引物进行逆转录聚合酶链反应（RT-PCR），扩增出一个与大量表达的纤维素合酶样基因NaCslD1相对应的片段。我们也扩增到了一个真正的CesA基因（NaCesA1）的片段，但在花粉管文库中无法鉴定到相应的cdna，这与NaCesA1基因的低表达水平一致。利用花花管RNA和引物设计到真菌FKS基因[编码(1,3)- β -葡聚糖合成酶]与其假定的植物同源基因（Gsl或葡聚糖合成酶样基因）之间的保守区域，进行RT-PCR扩增出了一个与大量表达的基因NaGsl1相对应的片段。通过RT-PCR检测到的第二个Gsl基因（NaGsl2）在未成熟花器官中低水平表达。介绍了NaCslD1、NaCesA1和NaGsl1的全长cdna的结构。NaCslD1和NaGsl1主要在雄性配子体（发育成熟的花粉和生长中的花粉管）中表达，我们认为它们编码了参与花粉管壁合成的两种p -葡聚糖合成酶的催化亚基。因此，沉积在一种细胞类型中的不同p -葡聚糖可能由来自不同基因家族的酶合成。
The walls deposited by growing pollen tubes contain two types of P-glucan, the (1,3)-beta -glucan callose and the (1, 4)-beta -glucan cellulose, as well as various a-linked pectic polysaccharides. Pollen tubes of Nicotiana alata Link et Otto, an ornamental tobacco, were therefore used to identify genes potentially encoding catalytic subunits of the callose synthase and cellulose synthase enzymes. Reverse transcriptase-polymerase chain reactions (RT-PCR) with pollen-tube RNA and primers designed to conserved regions of bacterial and plant cellulose synthase (CesA) genes amplified a fragment that corresponded to an abundantly expressed cellulose-synthase-like gene named NaCslD1. A fragment from a true CesA gene (NaCesA1) was also amplified, but corresponding cDNAs could not be identified in a pollen-tube library, consistent with the very low level of expression of the NaCesA1 gene. RT-PCR with pollen-tube RNA and primers designed to regions conserved between the fungal FKS genes [that encode (1,3)-beta -glucan synthases] and their presumed plant homologs (the Gsl or glucan-synthase-like genes) amplified a fragment that corresponded to an abundantly expressed gene named NaGsl1. A second Gsl gene detected by RT-PCR (NaGsl2) was expressed at low levels in immature floral organs. The structure of full-length cDNAs of NaCslD1, NaCesA1, and NaGsl1 are presented. Both NaCslD1 and NaGsl1 are predominantly expressed in the male gametophyte (developing and mature pollen and growing pollen tubes), and we propose that they encode the catalytic subunits of two P-glucan synthases involved in pollen-tube wall synthesis. Different P-glucans deposited in one cell type may therefore be synthesized by enzymes from different gene families.