Söderman E M, Brocard I M, Lynch T J, Finkelstein R R
Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, California 93106, USA.
Plant Physiol. 2000 Dec;124(4):1752-65. doi: 10.1104/pp.124.4.1752.
We have characterized developmental, environmental, and genetic regulation of abscisic acid-insensitive (ABI)4 gene expression in Arabidopsis. Although expressed most strongly in seeds, ABI4 transcripts are also present at low levels in vegetative tissue; vegetative expression is not induced by abscisic acid (ABA) or stress treatments. Comparison of transcript levels in mature seeds of ABA-insensitive, ABA-hypersensitive, ABA-deficient, or heterochronic mutants indicates that ABI4 expression is altered in only two of the backgrounds, the ABA-insensitive mutants abi1-1 and abi3-1. To determine whether ABI4 is necessary and/or sufficient for ABA response, we assayed the effects of loss of ABI4 function and ectopic ABI4 expression on growth and gene expression. We examined genetic interactions among three ABA response loci, ABI3, ABI4, and ABI5, by comparing phenotypes of mutants, ectopic expression lines, mutants carrying an ectopically expressed transgene, and the corresponding wild-type lines. Our results indicate some cross-regulation of expression among ABI3, ABI4, and ABI5 and suggest that they function in a combinatorial network, rather than a regulatory hierarchy, controlling seed development and ABA response.
我们已经对拟南芥中脱落酸不敏感（ABI）4基因表达的发育、环境和遗传调控进行了表征。尽管ABI4转录本在种子中表达最为强烈，但在营养组织中也有低水平表达；营养组织中的表达不受脱落酸（ABA）或胁迫处理的诱导。对ABA不敏感、ABA超敏感、ABA缺陷或异时突变体成熟种子中转录本水平的比较表明，只有在两种背景下ABI4的表达发生了改变，即ABA不敏感突变体abi1-1和abi3-1。为了确定ABI4对于ABA应答是否必要和/或充分，我们检测了ABI4功能缺失和异位表达对生长和基因表达的影响。我们通过比较突变体、异位表达系、携带异位表达转基因的突变体以及相应野生型系的表型，研究了三个ABA应答位点ABI3、ABI4和ABI5之间的遗传相互作用。我们的结果表明ABI3、ABI4和ABI5之间存在一些表达的交叉调控，并表明它们在一个控制种子发育和ABA应答的组合网络中发挥作用，而不是在一个调控层次中发挥作用。
