Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan.
Int Rev Cell Mol Biol. 2013;301:37-94. doi: 10.1016/B978-0-12-407704-1.00002-6.
LLA23, a member of the abscisic acid-, stress-, and ripening-induced (ASR) protein family, was previously isolated from lily (Lilium longiflorum) pollen. The lily ASR is induced through desiccation-associated ABA signaling transduction in the pollen. ASRs are highly hydrophilic and intrinsically unstructured proteins with molecular masses generally less than 18 kDa. LLA23 is abundant in the cytoplasm and nuclei of both vegetative and generative cells of pollen grains. The protein in the nucleus and in the cytoplasm is partly regulated by dehydration. A dual role is proposed for LLA23, as a regulator and a protective molecule, upon exposure to water deficits. This chapter reviews the current state of literature on Asr genes, protein structure, function, and their responses to various stresses. In a study, a genome-wide microarray was used to monitor the expression of LLA23-regulated genes, focusing on the relationship between ASR-, glucose-, and drought-inducible genes, and outlined the difference and cross talk of gene expression among these signaling networks. A strong association was observed in the expression of stress-responsive genes and found 25 genes that respond to all three treatments. Highly inducible genes were also found in each specific stress treatment. Promoter sequence analysis of LLA23-inducible genes enabled us not only to identify possible known cis-acting elements in the promoter regions but also to expect the existence of novel cis-acting elements involved in ASR-responsive gene expression. ASR can be used to improve crops and economically important plants against various environmental stresses.
LLA23 是脱落酸、胁迫和成熟诱导（ASR）蛋白家族的成员，先前从百合（Lilium longiflorum）花粉中分离得到。百合 ASR 是通过花粉中与干燥相关的 ABA 信号转导诱导产生的。ASR 是高度亲水的、内在无结构的蛋白质，分子量通常小于 18 kDa。LLA23 在花粉营养细胞和生殖细胞的细胞质和核中都很丰富。核内和细胞质内的蛋白质部分受脱水调节。LLA23 被提出具有双重作用，既是调节分子，也是在暴露于水分亏缺时的保护分子。本章综述了 Asr 基因、蛋白质结构、功能及其对各种胁迫响应的最新文献。在一项研究中，使用全基因组微阵列监测 LLA23 调控基因的表达，重点关注 ASR、葡萄糖和干旱诱导基因之间的关系，并概述了这些信号网络中基因表达的差异和串扰。观察到应激响应基因的表达存在很强的相关性，发现 25 个基因对这三种处理均有响应。在每种特定的胁迫处理中也发现了高度诱导的基因。LLA23 诱导基因启动子序列分析不仅使我们能够识别启动子区域中可能存在的已知顺式作用元件，而且还可以预期参与 ASR 响应基因表达的新顺式作用元件的存在。ASR 可用于提高作物和经济上重要的植物对各种环境胁迫的抗性。
