Wong L M, Abel S, Shen N, de la Foata M, Mall Y, Theologis A
Plant Gene Expression Center, Albany, CA 94710, USA.
Plant J. 1996 May;9(5):587-99. doi: 10.1046/j.1365-313x.1996.9050587.x.
The plant growth hormone auxin typified by indoleacetic acid (IAA) transcriptionally activates early genes in pea, PS-IAA4/5 and PS-IAA6, that are members of a multigene family encoding short-lived nuclear proteins. To gain first insight into the biological role of PS-IAA4/5 and PS-IAA6, promoter-beta-glucuronidase (GUS) gene fusions were constructed and their expression during early development of transgenic tobacco seedlings was examined. The comparative analysis reveals spatial and temporal expression patterns of both genes that correlate with cells, tissues, and developmental processes known to be affected by auxin. GUS activity in seedlings of both transgenic lines is located in the root meristem, sites of lateral root initiation and in hypocotyls undergoing rapid elongation. In addition, mutually exclusive cell-specific expression is evident. For instance, PS-IAA4/5-GUS but not PS-IAA6-GUS is expressed in root vascular tissue and in guard cells, whereas only PS-IAA6-GUS activity is detectable in glandular trichomes and redistributes to the elongating side of the hypocotyl upon gravitropic stimulation. Expression of PS-IAA4/5 and PS-IAA6 in elongating, dividing, and differentiating cell types indicates multiple functions during development. The common and yet distinct activity patterns of both genes suggest a combinatorial code of spatio-temporal co-expression of the various PS-IAA4/5-like gene family members in plant development that may mediate cell-specific responses to auxin.
以吲哚乙酸（IAA）为代表的植物生长激素生长素在转录水平上激活豌豆中的早期基因PS-IAA4/5和PS-IAA6，它们是一个多基因家族的成员，该家族编码寿命较短的核蛋白。为了初步了解PS-IAA4/5和PS-IAA6的生物学作用，构建了启动子- β-葡萄糖醛酸酶（GUS）基因融合体，并检测了它们在转基因烟草幼苗早期发育过程中的表达。比较分析揭示了这两个基因的时空表达模式，这些模式与已知受生长素影响的细胞、组织和发育过程相关。两个转基因系幼苗中的GUS活性位于根分生组织、侧根起始部位以及正在快速伸长的下胚轴中。此外，明显存在相互排斥的细胞特异性表达。例如，PS-IAA4/5-GUS在根维管组织和保卫细胞中表达，而PS-IAA6-GUS不表达，而仅在腺毛中可检测到PS-IAA6-GUS活性，并且在重力刺激下会重新分布到下胚轴的伸长侧。PS-IAA4/5和PS-IAA6在伸长、分裂和分化的细胞类型中的表达表明它们在发育过程中具有多种功能。这两个基因共同但又不同的活性模式表明，在植物发育过程中，各种PS-IAA4/5样基因家族成员的时空共表达组合密码可能介导细胞对生长素的特异性反应。
