Huang J C, Lin S M, Wang C S
Graduate Institute of Agricultural Biotechnology, National Chung Hsing University, Taichung, Taiwan.
Plant Cell Physiol. 2000 Apr;41(4):477-85. doi: 10.1093/pcp/41.4.477.
A cDNA clone encoding a desiccation-induced protein (LLA23) has been isolated from the mature pollen of a Lilium longiflorum cDNA library. Sequence analysis revealed significant similarity between the predicted LLA23 polypeptide, particularly at the C-terminal half of the sequence and a group of water-deficit/ripening-induced proteins. The expression of LLA23 gene is pollen-specific and the transcript accumulates only at the later stage of pollen maturation prior to anthesis. Premature drying of developing pollen confirmed that the accumulation of LLA23 transcripts was associated with desiccation. The LLA23 proteins decreased their levels when pollen/pollen tubes grew in the germination buffer. Treatments of pollen with abscisic acid (ABA) and polyethylene glycol (PEG)-8000 during germination greatly retarded the disappearance of LLA23 proteins and mRNAs. The LLA23 transcripts decreased their levels in pollen tubes grown both in vitro and in vivo, but the disappearance of LLA23 transcripts in tube cells grown in vivo was slower than those grown in vitro. In situ localization using anti-chicken immunoglobulin G conjugated with gold particles confirmed that LLA23 was located in the cytoplasm of pollen grains. The protective function of the desiccation-related proteins in the cytoplasm of pollen grains is proposed.
已从麝香百合cDNA文库的成熟花粉中分离出一个编码脱水诱导蛋白（LLA23）的cDNA克隆。序列分析显示，预测的LLA23多肽之间存在显著相似性，尤其是在序列的C端一半与一组水分亏缺/成熟诱导蛋白之间。LLA23基因的表达具有花粉特异性，转录本仅在花粉成熟后期、开花前积累。发育中的花粉过早干燥证实LLA23转录本的积累与脱水有关。当花粉/花粉管在萌发缓冲液中生长时，LLA23蛋白水平下降。在萌发过程中用脱落酸（ABA）和聚乙二醇（PEG）-8000处理花粉极大地延缓了LLA23蛋白和mRNA的消失。LLA23转录本在体外和体内生长的花粉管中水平均下降，但在体内生长的管细胞中LLA23转录本的消失比体外生长的要慢。使用与金颗粒偶联的抗鸡免疫球蛋白G进行原位定位证实LLA23位于花粉粒的细胞质中。提出了脱水相关蛋白在花粉粒细胞质中的保护功能。
