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Modulation of root‐skewing responses by KNAT 1 in A rabidopsis thaliana
Author(s) -
Qi Bin,
Zheng Huiqiong
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12295
Subject(s) - auxin , mutant , microbiology and biotechnology , green fluorescent protein , biology , lateral root , polar auxin transport , phenotype , arabidopsis thaliana , gene , genetics , arabidopsis
Summary The KNOTTED 1 homeobox ( KNOX ) family transcription factors are essential for stem cell establishment and maintenance and regulate various aspects of development in all green plants. Expression patterns of the KNOX genes in the roots of plants have been reported, but their role in development remains unclear. Here we show how the KNAT 1 gene is specifically involved in root skewing in A rabidopsis. The roots of two mutant alleles of KNAT 1 ( bp‐1 and bp‐5 ) exhibited exaggerated skewing to the right of gravity when grown on both vertical and tilted agar medium surfaces. This skewing phenotype was enhanced by treatments with low concentrations of propyzamide, and required auxin transport. The KNAT 1 mutation substantially decreased basipetal auxin transport and increased auxin accumulation in the roots. Using a PIN 2– GFP reporter and western blot analysis, we found that this alteration in auxin transport was accompanied by a decrease in PIN 2 levels in the root tip. Decreased PIN 2 expression in the mutant roots was not accompanied by reduced mRNA levels, suggesting that the KNAT 1 mutations affected PIN 2 expression at the posttranscriptional level. In vivo visualization of intracellular vacuolar targeting indicated that vacuolar degradation of PIN 2– GFP was significantly promoted in the root tips of the bp allelic mutants. Together, these results demonstrate that KNAT 1 negatively modulates root skewing, possibly by regulating auxin transport.