Pollen-Specific SKP1-Like Proteins are Components of Functional SCF Complexes and Essential for Lily Pollen Tube Elongation
Pollen-Specific SKP1-Like Proteins are Components of Functional SCF Complexes and Essential for Lily Pollen Tube Elongation
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DOI：
10.1093/pcp/pcp100
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发表时间：
2009-08-01
影响因子：
4.9
通讯作者：
Jauh, Guang-Yuh
中科院分区：
文献类型：
--
作者：
Chang, Liang-Chi;Guo, Cian-Ling;Jauh, Guang-Yuh
泛素蛋白酶体途径介导蛋白质降解，并参与植物发育和分化的各个方面，包括花粉管伸长和自交不亲和性。我们的特点是三个百合（百合）SKP 1-like基因，LSK 1 LSK 3，这是专门在花粉发育后期和伸长的花粉管中表达。LSK 1 LSK 3与拟南芥ASK 1具有高度同源性，其N端和C端分别含有一个与CUL 1和F-box相互作用的结构域。酵母双杂交和体外亲和结合试验表明，LSK与百合CULLIN 1相关。此外，LSK基因可以在功能上补充酵母skp 1缺失突变体YDR 328 C。为了研究它们在花粉管伸长中的生物学功能，建立了一种绿色荧光蛋白（GFP）标记的显性负性LSK 1 LSK 3的体内方法。用N-末端截短的LSK 1 LSK 3（LSK 1 LSK 3GFP）基因枪法处理花粉12 h后，在离体萌发和体内自花授粉和异花授粉中，均显著延缓了花粉管的伸长。有趣的是，在自花授粉花柱中，含有过表达LSK 2GFP和LSK 3GFP的花粉管的伸长基本上被抑制。大多数转LSK 2 GFP基因的花粉管只能在花柱柱头表面萌发，与对照相比，表现出显著的生长停滞。百合表现出典型的配子体自交不亲和通过一个未知的机制，但LSK 2和LSK 3可能参与这一复杂的机制。这些结果表明，LSK 1 LSK 3在调节基本的花粉管伸长在体外和体内的关键作用，26 S蛋白酶体介导的蛋白质途径在花粉管伸长中起着重要作用。
The ubiquitinproteasome pathway mediates protein degradation and is involved in diverse aspects of plant development and differentiation, including pollen tube elongation and self-incompatibility. We characterized three lily (Lilium longiflorum) SKP1-like genes, LSK1LSK3, that are specifically expressed in late pollen developmental stages and the elongating pollen tube. The encoded peptide sequences reveal that LSK1LSK3 share high identity with Arabidopsis ASK1 and contain a putative N-terminal CUL1- and a C-terminal F-box-interacting domain. Yeast two-hybrid and in vitro affinity binding assays revealed that the LSKs associate with lily CULLIN1. In addition, the LSK genes can functionally complement the yeast skp1 deletion mutant YDR328C. To investigate their biological functions in pollen tube elongation, an in vivo approach for green fluorescent protein (GFP)-tagged dominant-negative LSK1LSK3 was developed. Microprojectile bombardment with N-terminally truncated LSK1LSK3 (LSK1LSK3GFP) significantly retarded pollen tube elongation in both in vitro germination and in vivo self- and cross-pollination after 12h incubation. Interestingly, elongation of pollen tubes harboring overexpressed LSK2GFP and LSK3GFP was substantially inhibited within the self-pollinated styles. The elongation of most LSK2GFP-transformed pollen tubes could germinate only on the stigmatic surface of self style and showed statistically significant growth arrest as compared with control pollen tubes. Lily exhibits typical gametophytic self-incompatibility via an unknown mechanism, but LSK2 and LSK3 may be involved in this complex machinery. These results suggest critical roles for LSK1LSK3 in regulating fundamental pollen tube elongation in vitro and in vivo and that the 26S proteasome-mediated protein pathway plays an important role in pollen tube elongation.