Functional Analysis of OsKANADI1, A Florigen Hd3a Interacting Protein in Rice (Oryza sativa L.)

OsKANADI1 is considered as a florigen Hd3a interacting protein. To study the function of OsKANADI1, the expression pattern of OsKANADI1 was performed by semiquantitative RT-PCR with various wild-type tissues in the floral transition stage. The results demonstrated that OsKANADI1 was expressed in all organs of wild-type plants, but was highest in roots and leaves. We hypothesize that OsKANADI1 is a transcription factor in rice because it contains a GARP domain and posses a nuclear localization signal. To determine whether OsKANADI1 encodes a nuclear protein, full-length OsKANADI1 fused to GFP was introduced into onion epidermis cells by particle bombardment. The result revealed that OsKANADI1 was localized in the nucleus, suggesting that OsKANADI1 may be a transcription factor. Functional analysis was carried out using a reverse genetics approach to generate gain of function mutant (overexpression) and knockdown mutant (RNAi). The results showed that suppression of OsKANADI1 by RNAi displayed branching and increasing tiller number in several lines. This phenotype resembles to the Hd3a overexpressed plants indicating they possibly function in similar pathway.Key words : OsKANADI1, Transcription factor, Hd3a interacting protein, Ric

Functional Analysis of OsKANADI1, A Florigen Hd3a Interacting Protein in Rice (Oryza sativa L.)

OsKANADI1 is considered as a florigen Hd3a interacting protein. To study the function of OsKANADI1, the expression pattern of OsKANADI1 was performed by semiquantitative RT-PCR with various wild-type tissues in the floral transition stage. The results demonstrated that OsKANADI1 was expressed in all organs of wild-type plants, but was highest in roots and leaves. We hypothesize that OsKANADI1 is a transcription factor in rice because it contains a GARP domain and posses a nuclear localization signal. To determine whether OsKANADI1 encodes a nuclear protein, full-length OsKANADI1 fused to GFP was introduced into onion epidermis cells by particle bombardment. The result revealed that OsKANADI1 was localized in the nucleus, suggesting that OsKANADI1 may be a transcription factor. Functional analysis was carried out using a reverse genetics approach to generate gain of function mutant (overexpression) and knockdown mutant (RNAi). The results showed that suppression of OsKANADI1 by RNAi displayed branching and increasing tiller number in several lines. This phenotype resembles to the Hd3a overexpressed plants indicating they possibly function in similar pathway.Key words : OsKANADI1, Transcription factor, Hd3a interacting protein, Ric

The crystal structure of the plant small GTPase OsRac1 reveals its mode of binding to NADPH oxidase

This research was originally published in Journal of Biological Chemistry. Ken-ichi Kosami, Izuru Ohki, Minoru Nagano, Kyoko Furuita, Toshihiko Sugiki, Yoji Kawano, Tsutomu Kawasaki, Toshimichi Fujiwara, Atsushi Nakagawa, Ko Shimamoto and Chojiro Kojima. The crystal structure of the plant small GTPase OsRac1 reveals its mode of binding to NADPH oxidase. Journal of Biological Chemistry. 2014; 289, 28569-28578. © the American Society for Biochemistry and Molecular Biology

An NLR paralog Pit2 generated from tandem duplication of Pit1 fine-tunes Pit1 localization and function

NLR family proteins act as intracellular receptors. Gene duplication amplifies the number of NLR genes, and subsequent mutations occasionally provide modifications to the second gene that benefits immunity. However, evolutionary processes after gene duplication and functional relationships between duplicated NLRs remain largely unclear. Here, we report that the rice NLR protein Pit1 is associated with its paralogue Pit2. The two are required for the resistance to rice blast fungus but have different functions: Pit1 induces cell death, while Pit2 competitively suppresses Pit1-mediated cell death. During evolution, the suppression of Pit1 by Pit2 was probably generated through positive selection on two fate-determining residues in the NB-ARC domain of Pit2, which account for functional differences between Pit1 and Pit2. Consequently, Pit2 lost its plasma membrane localization but acquired a new function to interfere with Pit1 in the cytosol. These findings illuminate the evolutionary trajectory of tandemly duplicated NLR genes after gene duplication

DNA demethylation pathways: Additional players and regulators.

DNA demethylation can occur passively by "dilution" of methylation marks by DNA replication, or actively and independently of DNA replication. Direct conversion of 5-methylcytosine (5mC) to cytosine (C), as originally proposed, does not occur. Instead, active DNA methylation involves oxidation of the methylated base by ten-eleven translocations (TETs), or deamination of the methylated or a nearby base by activation induced deaminase (AID). The modified nucleotide, possibly together with surrounding nucleotides, is then replaced by the BER pathway. Recent data clarify the roles and the regulation of well-known enzymes in this process. They identify base excision repair (BER) glycosylases that may cooperate with or replace thymine DNA glycosylase (TDG) in the base excision step, and suggest possible involvement of DNA damage repair pathways other than BER in active DNA demethylation. Here, we review these new developments