Ca2+-responsive phospholipid-binding BONZAI genes confer a novel role for cotton resistance to Verticillium wilt.

Verticillium wilt which produced by the soil-borne fungus Verticillium dahliae is an important biotic threat that limits cotton (Gossypium hirsutum) growth and agricultural productivity. It is very essential to explore new genes for the generation of V. dahliae resistance or tolerance cotton varieties. Ca2+ signaling as a secondary messenger is involved in pathogen stress response. Despite Ca2+-responsive phospholipid-binding BONZAI (BON) genes have intensively been investigated in Arabidopsis, their function has not still been characterized in cotton. Here, we showed that three copies of GhBON1, two copies of GhBON2 and GhBON3 were found from the genome sequences of upland cotton. The expression of GhBON1 was inducible to V. dahliae. Knocking down of GhBON1, GhBON2 and GhBON3 using virus induced gene silencing (VIGS) each increased up-regulation of defense responses in cotton. These GhBON1, GhBON2 and GhBON3-silenced plants enhanced resistance to V. dahliae accompanied by higher burst of hydrogen peroxide and decreased cell death and had more effect on the up-regulation of defense response genes. Further analysis revealed that GhBON1 could interacts with BAK1-interacting receptor-like kinase 1 (GhBIR1) and pathogen-associated molecular pattern (PAMP) receptor regulator BAK1 (GhBAK1) at plasma membrane. Our study further reveals that plant Ca2+ -responsive phospholipid-binding BONZAI genes negatively regulate Verticillium wilt with the conserved function in response to disease resistance or plant immunity.

A maize calcineurin B-like interacting protein kinase ZmCIPK42 confers salt stress tolerance.

Calcineurin B-like (CBL) and CBL-interacting protein kinase (CIPK) play a crucial role in biotic and abiotic stress responses. However, the roles of different CIPKs in biotic and abiotic stress responses are less well characterized. In this study, we identified a mutation leading to an early protein termination of the maize CIPK gene ZmCIPK42 that undergoes a G to A mutation at the coding region via searching for genes involved in salt stress tolerance and ion homeostasis from maize with querying the EMS mutant library of maize B73. The mutant zmcipk42 plants have less branched tassel and impaired salt stress tolerance at the seedling stage. Quantitative real-time PCR analysis revealed that ZmCIPK42was expressed in diverse tissues and was induced by NaCl stress. A yeast two-hybrid screen identified a proteinase inhibitor (ZmMPI) as well as calcineurin B-like protein 1 and protein 4 (ZmCBL1, ZmCBL4) as interaction partners of ZmCIPK42. These interactions were further confirmed by bimolecular fluorescence complementation in plant cells. Moreover, over-expressing ZmCIPK42 resulted in enhanced tolerance to high salinity in both maize and Arabidopsis. These findings suggest that ZmCIPK42 is a positive regulator of salt stress tolerance and is a promising candidate gene to improve salt stress tolerance in maize through genetic manipulation.

Natural variation reveals that OsSAP16 controls low-temperature germination in rice.

Low temperature affects seed germination in plants, and low-temperature germination (LTG) is an important agronomic trait. Natural variation of LTG has been reported in rice, but the molecular basis for this variation is largely unknown. Here we report the phenotypic analysis of LTG in 187 rice natural accessions and a genome-wide association study (GWAS) of LTG in this collection. A total of 53 quantitative trait loci (QTLs) were found to be associated with LTG, of which 20 were located in previously reported QTLs. We further identified Stress-Associated Protein 16 (OsSAP16), coding for a zinc-finger domain protein, as a causal gene for one of the major LTG QTLs. Loss of OsSAP16 function reduces germination while greater expression of OsSAP16 enhances germination at low temperature. In addition, accessions with extremely high and low LTG values have correspondingly high and low OsSAP16 expression at low temperatures, suggesting that variation in expression of the OsSAP16 gene contributes to LTG variation. As the first case of identification of an LTG gene through GWAS, this study indicates that GWAS of natural accessions is an effective strategy in genetically dissecting LTG processes and gaining molecular understanding of low-temperature response and germination.

Sumoylation E3 Ligase SIZ1 Modulates Plant Immunity Partly through the Immune Receptor Gene SNC1 in Arabidopsis.

The small ubiqutin-like modifier E3 ligase SIZ1 regulates multiple processes in Arabidopsis, including salicylic-acid-dependent immune responses. However, the targets of SIZ1 in plant immunity are not known. Here, we provide evidence that the plant immune receptor nucleotide-binding leucine-rich repeat gene SNC1 partially mediates the regulation of plant immunity by SIZ1. The siz1 loss-of-function mutant has an autoimmune phenotype that is dependent on SNC1 and temperature. Overexpression of SIZ1 partially rescues autoimmune mutant phenotypes induced by activation or overaccumulation of SNC1, and the SNC1 protein amount is attenuated by SIZ1 overexpression. In addition, overexpression of the F-box protein CPR1 that degrades the SNC1 protein inhibits the growth defects and disease resistance of the siz1 mutant. Furthermore, we found that the SNC1 protein is sumoylated in planta. Although it remains to be determined whether SIZ1 primarily modulates the SNC1 protein via sumoylation or affects SNC1 transcript level, our data indicate that SNC1 is a major mediator of defense response modulated by SIZ1 and that SNC1 is a crucial target for fine-tuning plant defense responses.

Opposing Effects on Two Phases of Defense Responses from Concerted Actions of HEAT SHOCK COGNATE70 and BONZAI1 in Arabidopsis.

The plant immune system consists of multiple layers of responses targeting various phases of pathogen infection. Here, we provide evidence showing that two responses, one controlling stomatal closure and the other mediated by intracellular receptor proteins, can be regulated by the same proteins but in an antagonistic manner. The HEAT SHOCK COGNATE70 (HSC70), while previously known as a negative regulator of stomatal closure, is a positive regulator of immune responses mediated by the immune receptor protein SUPPRESSOR OF NPR1-1, CONSTITUTIVE1 (SNC1) as well as basal defense responses. In contrast to HSC70, a calcium-binding protein, BONZAI1 (BON1), promotes abscisic acid- and pathogen-triggered stomatal closure in addition to and independent of its previously known negative role in SNC1 regulation. BON1 likely regulates stomatal closure through activating SUPPESSOR OF THE G2 ALLELE OF SKP1 VARIANT B and inhibiting HSC70. New functions of BON1 and HSC70 identified in this study thus reveal opposite effects of each of them on immunity. The opposing roles of these regulators at different phases of plant immune responses exemplify the complexity in immunity regulation and suggest that immune receptors may guard positive regulators functioning at stomatal closure control.

ZmCIPK21, a maize CBL-interacting kinase, enhances salt stress tolerance in Arabidopsis thaliana.

Salt stress represents an increasing threat to crop growth and yield in saline soil. In this study, we identified a maize calcineurin B-like protein-interacting protein kinase (CIPK), ZmCIPK21, which was primarily localized in the cytoplasm and the nucleus of cells and displayed enhanced expression under salt stress. Over-expression of ZmCIPK21 in wild-type Arabidopsis plants increased their tolerance to salt, as supported by the longer root lengths and improved growth. The downstream stress-response genes, including dehydration-responsive element-binding (DREB) genes were also activated in transgenic plants over-expressing ZmCIPK21. In addition, introduction of the transgenic ZmCIPK21 gene into the Arabidopsis mutant cipk1-2 rescued the salt-sensitive phenotype under high salt stress. Measurement of Na+ and K+ content in transgenic plants showed that over-expression of ZmCIPK21 decreased accumulation of Na+ and allowed retention of relatively high levels of K+, thereby enhancing plant tolerance to salt conditions.

A novel role of the cotton calcium sensor CBL3 was involved in Verticillium wilt resistance in cotton.

BACKGROUND: Verticillium wilt, causes mainly by the soilborne pathogen Verticillium dahliae, is a devastated vascular disease resulting in huge financial losses in cotton, so research on improving V. dahliae stress tolerance in cotton is the utmost importance. Calcium as the second messenger acts as a crucial role in plant innate immunity. Cytosolic Ca2+during the pathogen infection is a significant increase in plant immune responses. Calcineurin B-like (CBL) proteins are widely known calcium sensors that regulate abiotic stress responses. However, the role of cotton CBLs in response to V. dahliae stress remains unclear. OBJECTIVE: To discover and utilize the gene to Verticillium wilt resistance and defense response mechanism of cotton. METHODS: Through screening the gene to Verticillium wilt resistance in cotton, four GhCBL3 copies were obtained from the current common cotton genome sequences. The protein domain and phylogenetic analyses of GhCBL3 were performed using NCBI Blast, DNAMAN, and MotifScan programs. Real-time RT-PCR was used to detect the expression of GhCBL3 gene in cotton seedlings under various stress treatments. The expression construct including GhCBL3 cDNA was transduced into Agrobacterium tumefaciens (GV3101) by heat shock method and transformed into cotton plants by Virus-Induced Gene Silencing (VIGS) method. The results of silencing of GhCBl3 on ROS accumulation and plant disease resistance in cotton plants were assessed. RESULTS: A member of calcineurin B-like proteins (defined as GhCBL3) in cotton was obtained. The expression of GhCBL3 was significantly induced and raised by various stressors, including dahliae, jasmonic acid (JA) and H2O2 stresses. Knockdown GhCBL3 in cotton by Virus-Induced Gene Silencing analysis enhanced Verticillium wilt tolerance and changed the occurrence of reactive oxygen species. Some disease-resistant genes were increased in GhCBL3-silencing cotton lines. CONCLUSION: GhCBL3 may function on regulating the Verticillium dahliae stress response of plants.

[Hydridotris(pyrazol-1-yl-κN(2))borato]bis-(methyl-amino-κN)(triphenyl-phos-phine-κP)ruthenium(II) chloride dichloro-methane solvate monohydrate.

The title salt, [Ru(Tp)(CH(5)N)(2)(PPh(3))]Cl·CH(2)Cl(2)·H(2)O [where Tp is (C(3)H(3)N(2))(3)BH and PPH(3) is C(18)H(15)P], has the Ru(III) atom in an octa-hedral geometry; one of the Ru-N(Tp) bonds [2.135 (8) Å] is slightly longer than another two, owing to the trans influence of PPh(3) ligand. N-H⋯Cl and O-H⋯Cl hydrogen bonding leads to the formation of layers parallel to (100).

Genome-wide transcriptome analysis of two maize inbred lines under drought stress.

Drought stress greatly affects plant growth and crop yield. To understand the transcriptome dynamics during drought stress in maize seedlings, genome-wide gene expression profiling was compared between the drought-tolerant line Han21 and drought-sensitive line Ye478 using Affymetrix Maize Genome Array containing 17,555 probe sets. The results showed that in response to drought, the Han21 line had fewer probe sets with significant expression change than the Ye478 line and both lines had a common set of ~2,600 regulated probe sets under drought stress. The potential components of the abscisic acid signaling pathway were significantly identified from the common probe sets. A total of 827 probe sets with significantly differential expression between the two lines under drought stress were identified. The differential expression levels of cell wall-related and transporter genes may contribute to the different tolerances of the two lines. Additionally, we found that, compared to the sensitive line Ye478, the transcriptional levels of drought-responsive probe sets in the tolerant line Han21 recovered more quickly after re-watering, and more probe sets in the tolerant line Han21 were exclusively up-regulated at the re-watering stage. Our study provides a global gene expression dynamics of two maize inbred lines during drought stress and re-watering and will be valuable for further study of the molecular mechanisms of drought tolerance in maize.

SsPsaH, a H subunit of the photosystem I reaction center of Suaeda salsa, confers the capacity of osmotic adjustment in tobacco.

BACKGROUND: Abiotic stress effects agricultural production, so research on improving stress tolerance of crop is important. Suaeda salsa is a halophyte with high salt and drought tolerance and ability to desalinate saline soil and improve soil quality. OBJECTIVE: To discover and utilize of salt and drought tolerance-related genes, we further investigated the mechanisms of salt and drought tolerance. METHODS: Through screening a salt treated Suaeda salsa cDNA library and further cloning a H subunit of the photosystem I reaction center SsPsaH cDNA, and then the protein domain and phylogenetic analyses of PSI genes was conducted with the NCBI Blast, DNAMAN, and MotifScan programs. The S. salsa seedlings were subjected to various stress treatments and analyze expression of SsPsaH under these treatments by real-time RT-PCR. SsPsaH expression construct was introduced into S. pombe cells by electroporation and transformed into N. tabacum plants by the leaf disc transformation method. RESULTS: A member of the H subunit of the Photosystem I reaction center (defined as SsPsaH) was obtained. The expression of SsPsaH was up-regulated by abscisic acid (ABA), salt, and drought stress treatments. Over-expressing SsPsaH in recombinant yeasts enhanced high salinity tolerance and increased tolerance to sorbitol during seed germination and seedling root development in tobacco, respectively. Some stress-related mark genes such as a LEA family gene of NtLEA, a binding protein of a drought response element of NtDREB, the ascorbate peroxidase gene (NtAPX) were also up-regulated in SsPsaH overexpressing transgenic tobacco lines. CONCLUSIONS: These results show that SsPsaH may contribute to the salt and osmotic stress response of plants.

Cloning and characterization of a calcium dependent protein kinase gene associated with cotton fiber development.

The gene GhCPK1 encoding a calcium dependent protein kinase was identified from cotton. Transcripts of GhCPK1 accumulated primarily in the elongating fiber, and Arabidopsis plants transformed with GhCPK1 promoter-GUS construct exhibited GUS activity mainly in the developing trichomes, roots, young leaves and sepals. In the bombarded onion epidermal cells, GhCPK1-GFP fusion proteins showed a subcellular distribution in the plasma membrane. In vitro assays indicated that GhCPK1 was a functional calcium-dependent kinase able to undergo autophosphorylation and phosphorylation of the known substrate histone III-S. Together, these results suggest that GhCPK1 may play a role in the calcium signaling events associated with fiber elongation.