Abstract
A temperature sensitive mutant of Arabidopsis, lignecens (lig), which accumulates lignin aberrantly at higher temperatures, was analyzed for elucidation of regulatory mechanisms of lignin biosynthesis. Whereas the lig seedlings grew normally at 18C, their growth was inhibited severely at 28C. Lignin was accumulated in the root sub-apical region of the lig seedling 2 days after temperature shift to 28C from 18C. We investigated effects of the lig mutation on expression patterns of several genes related to lignin formation, including AtPAL1, AtCCRs, AtCAD-D, and AtMYBs. Exposure of the lig seedlings to 28C increased the expression of AtPAL1, AtCCR2, and AtCAD-D. Ethylene synthesis inhibitor AVG suppressed aberrant lignification in the lig seedlings at 28C. A map-based approach identified a missense mutation in a putative serine/threonine kinase gene of the lig genome. Based on these results, a possible function of the LIG gene will be discussed.
