Abstract:

【Objective】 A new homolog of Arabidopsis ARGOS was isolated from leaves of Chinese cabbage inbred line Rikaze. Alignment of amino acid sequences and expression pattern were analyzed. The function of the gene was investigated by overexpressing it in Arabidopsis. The relation between the expression quantity of BrARGOS and the leaf heterosis of Chinese cabbage was analyzed. These results have provided data for investigating the functions of BrARGOS in Chinese cabbage. 【Method】 The cDNA sequence homologous to ARGOS was isolated from leaves of Chinese cabbage by RT-PCR. The secondary structure of the protein was predicted by DNAMAN PROGRAM. Expression pattern of BrARGOS was analyzed in different organs of Chinese cabbage by semiquantitive RT-PCR. The function of BrARGOS was investigated by transforming it into Arabidopsis. The relation between the expression quantity of BrARGOS and the leaf heterosis of Chinese cabbage was analyzed by semiquantitive RT-PCR. 【Result】 Using the Arabidopsis ARGOS sequence, a Blast search was performed against DNA sequences. The nucleotide sequence in BAC bank of Chinese cabbage was obtained and specific primers were designed. A new homolog with ARGOS was isolated from leaves of Chinese cabbage by RT-PCR and named BrARGOS. Alignment of predicted amino acid sequences of BrARGOS, Arabidopsis and tomato showed the proteins all contained Leu-rich C terminuses. The secondary structure of BrARGOS contained random coils, extended strands and alpha helixes. BrARGOS was expressed in all organs of Chinese cabbage, at high levels in young siliques and cotyledons, whereas at lowest level in cauline leaves. The result that NPTⅡ was transformed into Arabidopsis genome by examining genome DNA of positive Arabidopsis transformants confirmed foreign BrARGOS was transformed into Arabidopsis genome. Compared with vector control plants, the transgenic Arabidopsis had larger leaves and flowers, higher leaf fresh weight and plant height. 【Conclusion】 A new homolog with ARGOS was isolated from leaves of Chinese cabbage inbred line Rikaze. Expression pattern and function of BrARGOS were analyzed. Overexpression of BrARGOS in Arabidopsis increased aerial organ size. The Chinese cabbage BrARGOS gene is related to regulating plant organ size.

Key words: Chinese cabbage, BrARGOS, organ size, Arabidopsis