Berberine enhances defects in the establishment of leaf polarity in asymmetric leaves1 and asymmetric leaves2 of Arabidopsis thaliana.
Leaves develop as flat lateral organs from the indeterminate shoot apical meristem. The establishment of polarity along three-dimensional axes, proximal-distal, medial-lateral, and adaxial-abaxial axes, is crucial for the growth of normal leaves. The mutations of ASYMMETRIC LEAVES1 (AS1) and AS2 of Arabidopsis thaliana cause defects in repression of the indeterminate state and the establishment of axis formation in leaves. Although many mutations have been identified that enhance the adaxial-abaxial polarity defects of as1 and as2 mutants, the roles of the causative genes in leaf development are still unknown. In this study, we found that wild-type plants treated with berberine produced pointed leaves, which are often observed in the single mutants that enhance phenotypes of as1 and as2 mutants. The berberine-treated as1 and as2 mutants formed abaxialized filamentous leaves. Berberine, an isoquinoline alkaloid compound naturally produced in various plant sources, has a growth inhibitory effect on plants that do not produce berberine. We further showed that transcript levels of meristem-specific class 1 KNOX homeobox genes and abaxial determinant genes were increased in berberine-treated as1 and as2. Berberine treated plants carrying double mutations of AS2 and the large subunit ribosomal protein gene RPL5B showed more severe defects in polarity than did the as2 single mutant plants. We suggest that berberine inhibits (a) factor(s) that might be required for leaf adaxial cell differentiation through a pathway independent of AS1 and AS2. Multiple pathways might play important roles in the formation of flat symmetric leaves.
Plant Biology Research Center, Chubu University, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan.
Ayami
A
Nakagawa
Hiro
H
Takahashi
Shoko
S
Kojima
Nobuo
N
Sato
Kazuomi
K
Ohga
Byung Yoon
BY
Cha
Je-Tae
JT
Woo
Kazuo
K
Nagai
Gorou
G
Horiguchi
Hirokazu
H
Tsukaya
Yasunori
Y
Machida
Chiyoko
C
Machida
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001599:Berberine / Q000737:chemistry / Q000494:pharmacology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008652:Mesoporphyrins / Q000494:pharmacology; D046228:Microarray Analysis; D015394:Molecular Structure; D010641:Phenotype; D018515:Plant Leaves / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
C463739:AS2 protein, Arabidopsis; C456239:ASYMMETRIC LEAVES1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D008652:Mesoporphyrins; D014157:Transcription Factors; D001599:Berberine; C065420:N-methylmesoporphyrin IX