Invertase （INV） hydrolyzes sucrose into glucose and fructose, thereby playing key roles in primary metabolism and plant development. Based on their pH optima and sub-cellular locations, INVs are categorized into cel...Invertase （INV） hydrolyzes sucrose into glucose and fructose, thereby playing key roles in primary metabolism and plant development. Based on their pH optima and sub-cellular locations, INVs are categorized into cell wall, cytoplasmic, and vacuolar subgroups, abbreviated as CWlN, CIN, and VlN, respectively. The broad importance and implications of INVs in plant development and crop productivity have attracted enormous interest to examine INV function and regulation from multiple perspectives. Here, we review some exciting advances in this area over the last two decades, focusing on （1） new or emerging roles of INV in plant development and regulation at the post-translational level through interaction with inhibitors, （2） cross-talk between INV-mediated sugar signaling and hormonal control of development, and （3） sugar- and INV-mediated responses to drought and heat stresses and their impact on seed and fruit set. Finally, we discuss major questions arising from this new progress and outline future directions for unraveling mechanisms underlying INV-mediated plant development and their potential applications in plant biotechnology and agriculture.展开更多
Heterotrimeric GTP-binding proteins, which consist of Gα, Gβ, and Gγ subunits, play important roles in transducing extracellular signals perceived by cell surface receptors into intracellular physiological response...Heterotrimeric GTP-binding proteins, which consist of Gα, Gβ, and Gγ subunits, play important roles in transducing extracellular signals perceived by cell surface receptors into intracellular physiological responses. In addition to a single prototypical Gα protein （GPA1）, Arabidopsis has three unique Gα-Iike proteins, known as XLG1, XLG2, and XLG3, that have been found to be localized in nuclei, although their functions and mode of action remain largely unknown. Through a transcriptomic analysis, we found that XLG2 and XLG3 were rapidly induced by infection with the bacterial pathogen Pseudomonas syringae, whereas the XLG1 transcript level was not affected by pathogen infection. A reverse genetic screen revealed that the xlg2 loss-of-function mutation causes enhanced susceptibility to P. syringae. Transcriptome profiling revealed that the xlg2 mutation affects pathogen-triggered induction of a small set of defense-related genes. However, xlgl and xlg3 mutants showed no difference from wild-type plants in resistance to P. syringae, In addition, the xlg2 xlg3 double mutant and the xlgl xlg2 xlg3 triple mutant were not significantly different from the xlg2 single mutant in the disease resistance phenotype, suggesting that the roles of XLG1 and XLG3 in defense, if any, are less significant than for XLG2. Constitutive overexpression of XLG2 leads to the accumulation of abnormal transcripts from multiple defense-related genes. Through co-immunoprecipitation assays, XLG2 was found to interact with AGB1, the sole Gβ subunit in Arabidopsis, which has previously been found to be a positive regulator in resistance to necrotrophic fungal pathogens. However, no significant difference was found between three xlg single mutants, the xlg2 xlg3 double mutant, the xlgtriple mutant, and wild-type plants in resistance to the necrotrophic fungal pathogens Botrytis cinerea or Alternaria brassicicola. These results suggest that XLG2 and AGB1 are components of a G-protein complex different from the prototypical heterotrimeric G-protein and may have distinct functions in modulating defense responses.展开更多
文摘Invertase （INV） hydrolyzes sucrose into glucose and fructose, thereby playing key roles in primary metabolism and plant development. Based on their pH optima and sub-cellular locations, INVs are categorized into cell wall, cytoplasmic, and vacuolar subgroups, abbreviated as CWlN, CIN, and VlN, respectively. The broad importance and implications of INVs in plant development and crop productivity have attracted enormous interest to examine INV function and regulation from multiple perspectives. Here, we review some exciting advances in this area over the last two decades, focusing on （1） new or emerging roles of INV in plant development and regulation at the post-translational level through interaction with inhibitors, （2） cross-talk between INV-mediated sugar signaling and hormonal control of development, and （3） sugar- and INV-mediated responses to drought and heat stresses and their impact on seed and fruit set. Finally, we discuss major questions arising from this new progress and outline future directions for unraveling mechanisms underlying INV-mediated plant development and their potential applications in plant biotechnology and agriculture.
文摘Heterotrimeric GTP-binding proteins, which consist of Gα, Gβ, and Gγ subunits, play important roles in transducing extracellular signals perceived by cell surface receptors into intracellular physiological responses. In addition to a single prototypical Gα protein （GPA1）, Arabidopsis has three unique Gα-Iike proteins, known as XLG1, XLG2, and XLG3, that have been found to be localized in nuclei, although their functions and mode of action remain largely unknown. Through a transcriptomic analysis, we found that XLG2 and XLG3 were rapidly induced by infection with the bacterial pathogen Pseudomonas syringae, whereas the XLG1 transcript level was not affected by pathogen infection. A reverse genetic screen revealed that the xlg2 loss-of-function mutation causes enhanced susceptibility to P. syringae. Transcriptome profiling revealed that the xlg2 mutation affects pathogen-triggered induction of a small set of defense-related genes. However, xlgl and xlg3 mutants showed no difference from wild-type plants in resistance to P. syringae, In addition, the xlg2 xlg3 double mutant and the xlgl xlg2 xlg3 triple mutant were not significantly different from the xlg2 single mutant in the disease resistance phenotype, suggesting that the roles of XLG1 and XLG3 in defense, if any, are less significant than for XLG2. Constitutive overexpression of XLG2 leads to the accumulation of abnormal transcripts from multiple defense-related genes. Through co-immunoprecipitation assays, XLG2 was found to interact with AGB1, the sole Gβ subunit in Arabidopsis, which has previously been found to be a positive regulator in resistance to necrotrophic fungal pathogens. However, no significant difference was found between three xlg single mutants, the xlg2 xlg3 double mutant, the xlgtriple mutant, and wild-type plants in resistance to the necrotrophic fungal pathogens Botrytis cinerea or Alternaria brassicicola. These results suggest that XLG2 and AGB1 are components of a G-protein complex different from the prototypical heterotrimeric G-protein and may have distinct functions in modulating defense responses.
