Seyedi Mahdi, Selstam Eva, Timko Michael P., Sundqvist Christer
Botanical Institute, Department of Plant Physiology, Box 461, SE-40530 Göteborg, Sweden Department of Plant Physiology, University of Umeå, SE-901 87 Umeå, Sweden Department of Biology, University of Virginia, Charlottesville, VA 22901, USA.
Physiol Plant. 2001 Jun;112(2):261-272. doi: 10.1034/j.1399-3054.2001.1120215.x.
When grown in darkness the photomorphogenic lip1 mutant of pea (Pisum sativum L.) has a slender stem, expanded leaves, prolamellar body (PLB) lacking plastids with the size of chloroplasts and a low level of phytochrome A. The lack of PLBs in a dark-grown material (lip1) created a possibility to further study the regulation of their formation in relation to plant development. Inclusion of a cytokinin, 2-isopentenyladenine (2iP), in a medium supporting growth of the pea seedlings in darkness was found to reduce epicotyl length in the wild type. In lip1 the formation of a slender stem was inhibited and a short epicotyl developed. Furthermore, leaf expansion was inhibited, the plastid size reduced and the formation of PLBs induced. The PLB formation in lip1 was not accompanied by an increase in the amount of protochlorophyllide (Pchlide) or Pchilde oxidoreductase (POR). In the presence of 2iP the level of phytochrome A protein was increased in lip1 and the POR mRNA levels decreased in both lip1 and wild-type plants. The chloroplast characteristic trans-3-hexadecenoate acyl group of phosphatidylglycerol, present in the plastids of dark-grown lip1, was not influenced by 2iP. Thus, not all photomorphogenic processes reacted similarly in the lip1 mutant, but leaf expansion and plastid differentiation, including PLB formation, seemed to be regulated by the same signal transduction chain. Exogenously applied brassinolide could rescue neither dark- nor light-grown defects of the lip1 mutant. Thus, cytokinins but not brassinolides seem to be involved in the regulation of certain characteristic traits of skotomorphogenesis in pea, including plastid development and PLB formation.
在黑暗中生长时，豌豆（Pisum sativum L.）的光形态建成突变体lip1具有细长的茎、展开的叶片、缺乏类叶绿体大小质体的原片层体（PLB）以及低水平的光敏色素A。黑暗生长的材料（lip1）中缺乏PLB，这为进一步研究其形成与植物发育的关系创造了可能性。发现在支持豌豆幼苗在黑暗中生长的培养基中添加细胞分裂素2-异戊烯腺嘌呤（2iP）可缩短野生型的上胚轴长度。在lip1中，细长茎的形成受到抑制，短上胚轴发育。此外，叶片扩展受到抑制，质体大小减小，PLB的形成被诱导。lip1中PLB的形成并未伴随着原叶绿素酸酯（Pchlide）或Pchlide氧化还原酶（POR）含量的增加。在2iP存在的情况下，lip1中光敏色素A蛋白水平升高，lip1和野生型植物中POR mRNA水平均降低。黑暗生长的lip1质体中存在的磷脂酰甘油的叶绿体特征性反式-3-十六碳烯酸酰基不受2iP影响。因此，并非所有光形态建成过程在lip1突变体中的反应都相似，但叶片扩展和质体分化，包括PLB形成，似乎受相同的信号转导链调控。外源施加油菜素内酯无法挽救lip1突变体在黑暗或光照下生长的缺陷。因此，细胞分裂素而非油菜素内酯似乎参与了豌豆暗形态建成某些特征的调控，包括质体发育和PLB形成。
