Hauser B A, Cordonnier-Pratt M M, Pratt L H
Department of Botany, University of Georgia, Athens 30602, USA.
Plant J. 1998 May;14(4):431-9. doi: 10.1046/j.1365-313x.1998.00144.x.
Quantitative measurements of the absolute amounts of mRNAs transcribed from each of five phytochrome genes (PHYA, PHYB1, PHYB2, PHYE, PHYF) throughout the life cycle of a tomato plant and in response to changes in ambient light conditions are reported here. From their lowest level in unimbibed seed, all five transcripts increase by from 10- to 1000-fold during the first 24 h following the onset of imbibition, both in continuous darkness and in a greenhouse. In a greenhouse and on a whole-plant basis, all continue to increase throughout day 6, after which all but PHYE decline over the next week to a plateau at about one-half of the maximal value. PHYE mRNA differs in that in continues to increase in abundance during the first 2-3 weeks and thereafter remains at that maximal level. In adult plants, on a whole-plant basis and in decreasing order of abundance, PHYA, PHYB1, PHYE, PHYB2, and PHYF transcripts were present at approximately 120, 40, 40, 15, and 8 mumol microgram-1 of poly(A)(+)-enriched RNA, respectively. The data are consistent with the demonstrated roles of phytochromes A and B1 during seedling development and lead to the suggestion that phytochrome E might have a more important role in mature plants. Somewhat unexpectedly, PHYA and PHYB2 expression patterns are very similar. In seedlings, PHYA and PHYB2 exhibit the greatest increase in expression following a light-to-dark transition, as well as the greatest decrease following a dark-to-light transition. PHYA and PHYB2 are also similar in that both exhibit comparable variation on a natural diurnal cycle, while PHYB1 also exhibits variation but with a markedly different phase. The diurnal variation in expression of PHYA, PHYB1 and PHYB2 is consistent with the possibility that one or more of the phytochromes they encode is important with respect not only to photoperiodic behavior but also to the regulation of other events whose photosensitivity varies during a diurnal cycle.
本文报道了在番茄植株的整个生命周期中，以及对环境光照条件变化的响应下，对五个光敏色素基因（PHYA、PHYB1、PHYB2、PHYE、PHYF）各自转录的mRNA绝对量进行的定量测量。从未吸胀种子中的最低水平开始，在吸胀开始后的头24小时内，无论是在持续黑暗还是温室环境中，所有这五种转录本的含量都增加了10到1000倍。在温室中且以整株植物为基础，所有转录本在第6天全天都持续增加，此后除PHYE外，其他转录本在接下来的一周内下降至最大值的约一半并趋于平稳。PHYE mRNA的不同之处在于，其丰度在最初的2至3周内持续增加，此后保持在最大值水平。在成年植株中，以整株植物为基础且按丰度递减顺序排列，PHYA、PHYB1、PHYE、PHYB2和PHYF转录本分别以约120、40、40、15和8 μmol μg⁻¹的聚腺苷酸（poly(A)）富集RNA的形式存在。这些数据与光敏色素A和B1在幼苗发育过程中已证实的作用一致，并表明光敏色素E在成熟植株中可能具有更重要的作用。 somewhat unexpectedly（此处原文似乎有误，可能是Somewhat unexpectedly），PHYA和PHYB2的表达模式非常相似。在幼苗中，PHYA和PHYB2在从光到暗的转变后表达增加最多，在从暗到光转变后下降最多。PHYA和PHYB2还具有相似之处，即在自然昼夜周期中都表现出相当的变化，而PHYB1也表现出变化，但相位明显不同。PHYA、PHYB1和PHYB2表达的昼夜变化符合这样一种可能性，即它们编码的一种或多种光敏色素不仅对光周期行为很重要，而且对其他在昼夜周期中光敏性变化的事件的调节也很重要。
