Prevacuolar compartments （PVCs） and endosomal compartments are membrane-bound organelles mediating protein traffic to vacuoles in the secretory and endocytic pathways of plant cells. Over the years, great progress h...Prevacuolar compartments （PVCs） and endosomal compartments are membrane-bound organelles mediating protein traffic to vacuoles in the secretory and endocytic pathways of plant cells. Over the years, great progress has been made towards our understanding in these two compartments in plant cells. In this review, we will summarize our contributions toward the identification and characterization of plant prevacuolar and endosomal compartments. Our studies will serve as important steps in future molecular characterization of PVC biogenesis and PVC-mediated protein traffickinq in plant cells.展开更多
The rice pattern recognition receptor （PRR） XA21 confers race-specific resistance in leaf infection by bacterial blight Xathornonas oryzae pv. oryzae （Xoo）, and was shown to be primarily localized to the endoplasm...The rice pattern recognition receptor （PRR） XA21 confers race-specific resistance in leaf infection by bacterial blight Xathornonas oryzae pv. oryzae （Xoo）, and was shown to be primarily localized to the endoplasmic reticulum （ER） when expressed with its native promoter or overexpressed in the protoplast. However, whether the protein is still ER- localization in the intact cell when overexpressed remains to be identified. Here, we showed that XA21, its kinase-dead mutant XA21PK736EP and the triple autophosphorylation mutant XA21PS686AJT688AJS699A GFP fusions were primarily localized to the plasma membrane （PM） when overexpressed in the intact transgenic rice cell, and also localized to the ER in the transgenic protoplast. The transgenic plants constitutively expressing the wild-type XA21 or its GFP fusion displayed racespecific resistance to Xoo at the adult and seedling stages. XA21 and XA21PK736EP could be internalized probably via the SCAMP-positive early endosomal compartment in the protoplast, suggesting that XA21 might be endocytosed to initiate resistance responses during pathogen infection. We also established a root infection system and demonstrated that XA21 also mediated race-specific resistance responses to Xoo in the root. Our current study provides an insight into the nature of the XA21-mediated resistance and a practical approach using the root cell system to further dissect the cellular signaling of the PRR during the rice-Xoo interaction.展开更多
Nitrogen （N） metabolism is essential for the biosynthesis of vital biomolecules. N status thus exerts profound effects on plant growth and development, and must be closely monitored. In bacteria and fungi, a few sop...Nitrogen （N） metabolism is essential for the biosynthesis of vital biomolecules. N status thus exerts profound effects on plant growth and development, and must be closely monitored. In bacteria and fungi, a few sophisticated N sensing systems have been extensively studied. In animals, the ability to receive amino acid signals has evolved to become an integral part of the nervous coordination system. In this review, we will summarize recent developments in the search for putative N sensing systems in higher plants based on homologous systems in bacteria, fungi, and animals. Apparently, although plants have separated and diversified from other organisms during the evolution process, striking similarities can be found in their N sensing systems compared with those of their counterparts; however, our understanding of these systems is still incomplete. Significant modifications of the N sensing systems （including cross-talk with other signal transduction pathways） in higher plants may be a strategy of adaptation to their unique mode of life.展开更多
基金Supported by grants from the Research Grants Council of Hong Kong(CUHK4156/01M,CUHK4260/02M,CUHK4307/03M,and CUHK4580/05M)National Science Foundation of China (30529001)+1 种基金CUHK Scheme C,UGCAoE(B-07/99)Germany/HK Joint Research Scheme to L.Jiang.
文摘Prevacuolar compartments （PVCs） and endosomal compartments are membrane-bound organelles mediating protein traffic to vacuoles in the secretory and endocytic pathways of plant cells. Over the years, great progress has been made towards our understanding in these two compartments in plant cells. In this review, we will summarize our contributions toward the identification and characterization of plant prevacuolar and endosomal compartments. Our studies will serve as important steps in future molecular characterization of PVC biogenesis and PVC-mediated protein traffickinq in plant cells.
文摘The rice pattern recognition receptor （PRR） XA21 confers race-specific resistance in leaf infection by bacterial blight Xathornonas oryzae pv. oryzae （Xoo）, and was shown to be primarily localized to the endoplasmic reticulum （ER） when expressed with its native promoter or overexpressed in the protoplast. However, whether the protein is still ER- localization in the intact cell when overexpressed remains to be identified. Here, we showed that XA21, its kinase-dead mutant XA21PK736EP and the triple autophosphorylation mutant XA21PS686AJT688AJS699A GFP fusions were primarily localized to the plasma membrane （PM） when overexpressed in the intact transgenic rice cell, and also localized to the ER in the transgenic protoplast. The transgenic plants constitutively expressing the wild-type XA21 or its GFP fusion displayed racespecific resistance to Xoo at the adult and seedling stages. XA21 and XA21PK736EP could be internalized probably via the SCAMP-positive early endosomal compartment in the protoplast, suggesting that XA21 might be endocytosed to initiate resistance responses during pathogen infection. We also established a root infection system and demonstrated that XA21 also mediated race-specific resistance responses to Xoo in the root. Our current study provides an insight into the nature of the XA21-mediated resistance and a practical approach using the root cell system to further dissect the cellular signaling of the PRR during the rice-Xoo interaction.
基金Supported by the Hong Kong UGC Area of Excellence on Plant and Fungal Biotechnology Center and Hong Kong RGC earmarked grant CUHK4263/ 00M
文摘Nitrogen （N） metabolism is essential for the biosynthesis of vital biomolecules. N status thus exerts profound effects on plant growth and development, and must be closely monitored. In bacteria and fungi, a few sophisticated N sensing systems have been extensively studied. In animals, the ability to receive amino acid signals has evolved to become an integral part of the nervous coordination system. In this review, we will summarize recent developments in the search for putative N sensing systems in higher plants based on homologous systems in bacteria, fungi, and animals. Apparently, although plants have separated and diversified from other organisms during the evolution process, striking similarities can be found in their N sensing systems compared with those of their counterparts; however, our understanding of these systems is still incomplete. Significant modifications of the N sensing systems （including cross-talk with other signal transduction pathways） in higher plants may be a strategy of adaptation to their unique mode of life.
