Response of Wheat Fungal Diseases to Elevated Atmospheric CO2 Level

Infection with fungal pathogens on wheat varieties with different levels of resistance was tested at ambient (NC, 390 ppm) and elevated (EC, 750 ppm) atmospheric CO2 levels in the phytotron. EC was found to affect many aspects of the plant-pathogen interaction. Infection with most fungal diseases was usually found to be promoted by elevated CO2 level in susceptible varieties. Powdery mildew, leaf rust and stem rust produced more severe symptoms on plants of susceptible varieties, while resistant varieties were not infected even at EC. The penetration of Fusarium head blight (FHB) into the spike was delayed by EC in Mv Mambo, while it was unaffected in Mv Regiment and stimulated in Mv Emma. EC increased the propagation of FHB in Mv Mambo and Mv Emma. Enhanced resistance to the spread of Fusarium within the plant was only found in Mv Regiment, which has good resistance to penetration but poor resistance to the spread of FHB at NC. FHB infection was more severe at EC in two varieties, while the plants of Mv Regiment, which has the best field resistance at NC, did not exhibit a higher infection level at EC. The above results suggest that breeding for new resistant varieties will remain a useful means of preventing more severe infection in a future with higher atmospheric CO2 levels

Primary macrophages and J774 cells respond differently to infection with Mycobacterium tuberculosis

10.1038/srep42225Scientific Reports74222

Gene and genome duplications and the origin fo C4 photosysnthesis: Birth of a trait in the Cleomaceae

C4 photosynthesis is a trait that has evolved in 66 independent plant lineages and increases the efficiency of carbon fixation. The shift from C3 to C4 photosynthesis requires substantial changes to genes and gene functions effecting phenotypic, physiological and enzymatic changes. We investigate the role of ancient whole genome duplications (WGD) as a source of new genes in the development of this trait and compare expression between paralog copies. We compare Gynandropsis gynandra, the closest relative of Arabidopsis that uses C4 photosynthesis, with its C3 relative Tarenaya hassleriana that underwent a WGD named Th-a. We establish through comparison of paralog synonymous substitution rate that both species share this paleohexaploidy. Homologous clusters of photosynthetic gene families show that gene copy numbers are similar to what would be expected given their duplication history and that no significant difference between the C3 and C4 species exists in terms of gene copy number. This is further confirmed by syntenic analysis of T. hassleriana, Arabidopsis thaliana and Aethionema arabicum, where syntenic region copy number ratios lie close to what could be theoretically expected. Expression levels of C4 photosynthesis orthologs show that regulation of transcript abundance in T. hassleriana is much less strictly controlled than in G. gynandra, where orthologs have extremely similar expression patterns in different organs, seedlings and seeds. We conclude that the Th-a and older paleopolyploidy events have had a significant influence on the specific genetic makeup of Cleomaceae versus Brassicaceae. Because the copy number of various essential genes involved in C4 photosynthesis is not significantly influenced by polyploidy combined with the fact that transcript abundance in G. gynandra is more strictly controlled, we also conclude that recruitment of existing genes through regulatory changes is more likely to have played a role in the shift to C4 than the neofunctionalization of duplicated genes

Gene and genome duplications and the origin fo C4 photosysnthesis: Birth of a trait in the Cleomaceae

C4 photosynthesis is a trait that has evolved in 66 independent plant lineages and increases the efficiency of carbon fixation. The shift from C3 to C4 photosynthesis requires substantial changes to genes and gene functions effecting phenotypic, physiological and enzymatic changes. We investigate the role of ancient whole genome duplications (WGD) as a source of new genes in the development of this trait and compare expression between paralog copies. We compare Gynandropsis gynandra, the closest relative of Arabidopsis that uses C4 photosynthesis, with its C3 relative Tarenaya hassleriana that underwent a WGD named Th-a. We establish through comparison of paralog synonymous substitution rate that both species share this paleohexaploidy. Homologous clusters of photosynthetic gene families show that gene copy numbers are similar to what would be expected given their duplication history and that no significant difference between the C3 and C4 species exists in terms of gene copy number. This is further confirmed by syntenic analysis of T. hassleriana, Arabidopsis thaliana and Aethionema arabicum, where syntenic region copy number ratios lie close to what could be theoretically expected. Expression levels of C4 photosynthesis orthologs show that regulation of transcript abundance in T. hassleriana is much less strictly controlled than in G. gynandra, where orthologs have extremely similar expression patterns in different organs, seedlings and seeds. We conclude that the Th-a and older paleopolyploidy events have had a significant influence on the specific genetic makeup of Cleomaceae versus Brassicaceae. Because the copy number of various essential genes involved in C4 photosynthesis is not significantly influenced by polyploidy combined with the fact that transcript abundance in G. gynandra is more strictly controlled, we also conclude that recruitment of existing genes through regulatory changes is more likely to have played a role in the shift to C4 than the neofunctionalization of duplicated genes

Abscisic Acid Modulates Neighbor Proximity-Induced Leaf Hyponasty in Arabidopsis.

Leaves of shade-avoiding plants such as Arabidopsis (Arabidopsis thaliana) change their growth pattern and position in response to low red to far-red ratios (LRFRs) encountered in dense plant communities. Under LRFR, transcription factors of the phytochrome interacting factor (PIF) family are de-repressed. PIFs induce auxin production, which is required for promoting leaf hyponasty, thereby favoring access to unfiltered sunlight. Abscisic acid (ABA) has also been implicated in the control of leaf hyponasty, with gene expression patterns suggesting that LRFR regulates the ABA response. Here, we show that LRFR leads to a rapid increase in ABA levels in leaves. Changes in ABA levels depend on PIFs, which regulate the expression of genes encoding isoforms of the enzyme catalyzing a rate-limiting step in ABA biosynthesis. Interestingly, ABA biosynthesis and signaling mutants have more erect leaves than wild-type Arabidopsis under white light but respond less to LRFR. Consistent with this, ABA application decreases leaf angle under white light; however, this response is inhibited under LRFR. Tissue-specific interference with ABA signaling indicates that an ABA response is required in different cell types for LRFR-induced hyponasty. Collectively, our data indicate that LRFR triggers rapid PIF-mediated ABA production. ABA plays a different role in controlling hyponasty under white light than under LRFR. Moreover, ABA exerts its activity in multiple cell types to control leaf position