Os04g0659300

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Annotated Information

Function

The apoplast of plant cells, which carries out multiple functions in plant metabolism and signaling, is not only a barrier but also the linker between the environment and the protoplast. To investigate the role of apoplastic proteins in the salt stress response, 10-d-old rice (Oryza sativa) plants were treated with 200 mM NaCl for 1, 3, or 6 h, and the soluble apoplast proteins were extracted for differential analysis compared with untreated controls using two-dimensional electrophoresis. Ten protein spots that increased or decreased significantly in abundance were identified by mass spectrometry. These proteins included some well-known biotic and abiotic stress-related proteins. Among them, an apoplastic protein, with extracellular domain-like cysteine-rich motifs (DUF26), O. sativa root meander curling (OsRMC), has shown drastically increased abundance in response to salt stress during the initial phase. OsRMC RNA interference transgenic rice has been generated to assess the function of OsRMC in the salt stress response. The results show that knocking down the expression level of OsRMC in transgenic rice led to insensitive seed germination, enhanced growth inhibition, and improved salt stress tolerance to NaCl than in untransgenic plants. These results indicate that plant apoplastic proteins may have important roles in the plant salt stress response.

Expression

Jasmonic acid (JA) is a well-known defence hormone, but its biological function and mechanism in rice root development are less understood. Here, we describe a JA-induced putative receptor-like protein (OsRLK, AAL87185) functioning in root development in rice. RNA in situ hybridization revealed that the gene was expressed largely in roots, and a fusion protein showed its localization on the plasma membrane. The primary roots in RNAi transgenic rice plants meandered and curled more easily than wild-type (WT) roots under JA treatment. Thus, this gene was renamed Oryza sativa root meander curling (OsRMC). The transgenic primary roots were shorter, the number of adventitious roots increased and the number of lateral roots decreased as compared to the WT. As well, the second sheath was reduced in length. Growth of both primary roots and second sheaths was sensitive to JA treatment. No significant change of JA level appeared in the roots between the transgenic rice line and WT. Expression of RSOsPR10, involved in the JA signalling pathway, was induced in transgenic rice. Western blotting revealed OsRMC induced by JA. Our results suggest that OsRMC of the DUF26 subfamily involved in JA signal transduction mediates root development and negatively regulates root curling in rice.

Evolution

A number of studies have beenperformed using proteomic approaches to identify pathogen response proteins in rice and Arabidopsis(Kim et al., 2003; Ndimba et al., 2003) and salt stress response proteins in the rice microsome (Lee et al.,2004), root (Yan et al., 2005), and leaf sheath (Abbasi and Komatsu, 2004). Dani et al. (2005) used a proteomic approach to analyze the proteome changes in the tobacco (Nicotiana tabacum) leaf apoplast during longterm (20 d) salt stress. Nevertheless, few studies have addressed the changes in the apoplast proteome in response to salt stress, especially during the initial phase of salt stress. In this study, the changes in the rice root apoplast proteins during the initial phase of salt stress were carefully investigated by twodimensional electrophoresis (2-DE). Eight salt stressregulated apoplast proteins were identified, including a secreted protein with extracellular domain-like Cysrich motifs (DUF26) that has been reported to be involved in O. sativa root meander curling (OsRMC; Jiang et al., 2007). In our work, the roles of OsRMC in the response to salt stress have been revealed. OsRMC was up-regulated at the transcriptional and translational levels during the initial phase of salt stress. Our findings showed that knocking down the expression level of OsRMC resulted in more resistance to salt stress in transgenic rice.

Labs working on this gene

Research Center for Molecular Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, and Graduate School of the Chinese Academy of Sciences, Beijing, China. Lei Zhang, Li-Hong Tian, Jun-Feng Zhao, Yun Song, Cui-Jun Zhang and Yi Guo Institute of Molecular and Cell Biology, Hebei Normal University, Shijiazhuang 050016, China

References

1. Lei Zhang;Li-Hong Tian;Jun-Feng Zhao;Yun Song;Cui-Jun Zhang;Yi Guo

 Identification of an Apoplastic Protein Involved in the Initial Phase of Salt Stress Response in Rice Root by Two-Dimensional Electrophoresis
 Plant Physiology, 2009, 149(2): 916-928

2. Jiafu Jiang;Junhua Li;Yunyuan Xu;Ye Han;Yue Bai;Guoxin Zhou;Yonggen Lou;Zhihong Xu;Kang Chong

 RNAi knockdown of Oryza sativa root meander curling gene led to altered root development and coiling which were mediated by jasmonic acid signalling in rice
 Plant, Cell & Environment, 2007, 30(6): 690-699

3. Yang Y, Peng H, Huang H, Wu J, Jia S, Huang D, Lu T

Large-scale production of enhancer trapping lines for rice functional genomics.

Plant Sci，2004，167: 281–288