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The cytokinin 2‐isopentenyladenine causes partial reversion to skotomorphogenesis and induces formation of prolamellar bodies and protochlorophyllide 657 in the lip 1 mutant of pea
Author(s) -
Seyedi Mahdi,
Selstam Eva,
Timko Michael P.,
Sundqvist Christer
Publication year - 2001
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2001.1120215.x
Subject(s) - epicotyl , protochlorophyllide , plastid , phytochrome , biology , chloroplast , mutant , darkness , photomorphogenesis , pisum , microbiology and biotechnology , cytokinin , botany , biochemistry , arabidopsis , auxin , gene , hypocotyl , red light
When grown in darkness the photomorphogenic lip 1 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 ( lip 1) 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 lip 1 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 lip 1 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 lip 1 and the POR mRNA levels decreased in both lip 1 and wild‐type plants. The chloroplast characteristic trans ‐3‐hexadecenoate acyl group of phosphatidylglycerol, present in the plastids of dark‐grown lip 1, was not influenced by 2iP. Thus, not all photomorphogenic processes reacted similarly in the lip 1 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 lip 1 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.