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Defective Etioplasts Observed in Variegation Mutants May Reveal the Light‐Independent Regulation of White/Yellow Sectors of Arabidopsis Leaves
Author(s) -
Wu Wenjuan,
Elsheery Nabil,
Wei Qing,
Zhang Lingang,
Huang Jirong
Publication year - 2011
Publication title -
journal of integrative plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.734
H-Index - 83
eISSN - 1744-7909
pISSN - 1672-9072
DOI - 10.1111/j.1744-7909.2011.01079.x
Subject(s) - variegation (histology) , plastid , mutant , biology , chloroplast , thylakoid , gene , arabidopsis , genetics , nuclear gene , botany , microbiology and biotechnology , genome
Leaf variegation resulting from nuclear gene mutations has been used as a model system to elucidate the molecular mechanisms of chloroplast development. Since most variegation genes also function in photosynthesis, it remains unknown whether their roles in photosynthesis and chloroplast development are distinct. Here, using the variegation mutant thylakoid formation1 ( thf1 ) we show that variegation formation is light independent. It was found that slow and uneven chloroplast development in thf1 can be attributed to defects in etioplast development in darkness. Ultrastructural analysis showed the coexistence of plastids with or without prolamellar bodies (PLB) in cells of thf1 , but not of WT. Although THF1 mutation leads to significant decreases in the levels of Pchlide and Pchllide oxidoreductase (POR) expression, genetic and 5‐aminolevulinic acid (ALA)‐feeding analysis did not reveal Pchlide or POR to be critical factors for etioplast formation in thf1. Northern blot analysis showed that plastid gene expression is dramatically reduced in thf1 compared with that in WT, particularly in the dark. Our results also indicate that chlorophyll biosynthesis and expression of plastidic genes are coordinately suppressed in thf1 . Based on these results, we propose a model to explain leaf variegation formation from the plastid development perspective.