The Use of Plant Growth-Promoting Rhizobacteria (PGPR) and an Arbuscular Mycorrhizal Fungus (AMF) to Improve Plant Growth in Saline Soils for Phytoremediation

Upstream oil and gas production has caused soil salinity problems across western Canada. In this work we investigated the use of ACC (1-aminocyclopropane-1-carboxylate) deaminase-producing plant growth-promoting rhizobacteria (PGPR) and the arbuscular mycorrhizal fungus (AMF) Glomus intraradices to enhance the efficiency and feasibility of phytoremediation of saline soils. This work involved laboratory and field research for three sites in south east Saskatchewan, Canada. The three research sites were Cannington Manor South (CMS), Cannington Manor North (CMN) and Alameda (AL). CMS and AL were highly saline, while the CMN site had moderate salinity. Indigenous PGPR were isolated from these sites and tested in greenhouse experiments using authentic salt-contaminated soils taken from the research sites. Increased plant biomass by PGPR and/or AMF was observed. This growth promotion effect varied with plant species, soil salinity and soil fertility. The combination treatment of two previously isolated PGPR Pseudomonas putida UW3 and UW4 (noted as UW3+4) from farm soil in Ontario consistently promoted shoot growth of both barley and oats grown in saline soils by approximately 100%. The indigenous PGPR Pseudomonas corrugata (CMH3) and Acinetobacter haemolyticus (CMH2) also promoted plant growth on par with UW3+4. In addition, in one experiment where alfalfa was tested, UW3+4, CMH2 and CMH3 treatments not only enhanced shoot biomass but also increased root nodulation. For AMF effects, G. intraradices enhanced biomass of oats and barley. Furthermore, the AMF+CMH3 was effective in promoting growth of Topgun ryegrass, while AMF+CMH2 was beneficial for Inferno tall fescue growth in salt impacted soils. The concentration of NaCl in the plants grown in salt-impacted soils ranged from 24 – 83 g/kg. There was no evidence of an increase in NaCl concentrations of plant tissue by PGPR and/or AMF treatments. In addition, to determine the importance of nutrient addition to research sites, liquid fertilizer was applied to 2-week old plants. Results demonstrated that fertilizer effectively increased biomass, and more importantly the biomass of PGPR treated plants supplied with fertilizer was approximately 20% higher than that of plants treated with fertilizer alone. Therefore, research sites were then amended with compost before planting of the 2007 field trial. Plant growth promotion by UW3+4 and CMH3 was tested in the summer of 2007 in the field. Prior to planting, soils were sampled from each site for soil salinity analysis. Barley, oats, tall fescue and ryegrass treated with and without PGPR were sown in plots. The plant coverage condition, NaCl concentrations and biomass of plant shoots were assessed to evaluate the PGPR effect. The results showed that PGPR promoted shoot dry weight by 30% - 175%. The NaCl concentrations of barley, oats and tall fescue averaged 53 g/kg, 66 g/kg and 35 g/kg, respectively. There was no evidence of an increase in NaCl concentrations of plant tissue by PGPR in the field. The salt removal of the CMN site was the highest among three sites due to the large amount of shoot biomass produced. The amount of salt accumulated in the shoots on the CMN site is estimated to be 1580 kg per hectare per year when both barley and ryegrass are planted together as a mix and treated with PGPR. Based on the field data, the estimated time required to remove 50% salt in the top 50 cm soil is seven years with PGPR treatments, while it takes fifteen years to do so without PGPR. In conclusion, PGPR-promoted phytoremediation was proven to be a feasible and effective remediation technique for soils with moderate salinity

Localization and possible functions of Arabidopsis HOTHEAD protein

Molecular analyses using sixteen insertion-deletion polymorphic markers revealed that somatic sectoring occurs relatively frequently during the course of normal vegetative development. This is the first report that documents the spontaneous but targeted appearance of unique genomic insertions at multiple discreet loci in single plants. These sectors hosted genetic variation attributed to single nucleotide changes, insertions, or sequence loss. The most important finding is the appearance of a 54 base-pair insertion in the progeny that resulted in an identical sequence match with the corresponding allele of the grand-parental genome, rather than the genome of the immediate parent. Because somatic sectoring was observed five times more frequently in hothead (hth) mutant plants, studies were initiated to determine HTH protein localization with a view toward elucidating its possible functions. Here, I present the results of HTH protein localization using a fluorescent protein-tagged HTH fusion protein generated by a native promoter-driven construct (annotated as HTHpro:HTH-FP). The HTH-FP protein was predominantly localized to the epidermis of seedling and mature tissues; moreover, it was also present in the seed coat outer integument that is of epidermal origin. Most interestingly, in seedlings the HTH-FP protein was localized to the endoplasmic reticulum (ER) and ER-derived structures called ER bodies. Since ER bodies have been previously associated with stress response, the ER body localization suggests a role of HTH in stress responses. This notion is supported by the effect of the wounding hormone methyl jasmonate which elevated HTH expression in wildtype plants and induced ER bodies in rosette leaf epidermis of HTHpro:HTH-FP plants. Previously, HTH has been proposed to function either as a mandelonitrile lyase involved in cyanogenesis or as a fatty alcohol dehydrogenase involved in the biosynthesis of cutin monomers (fatty acids). To determine whether HTH has any of these catalytic activities, a maltose binding protein (MBP)-HTH fusion protein was generated in bacteria and the recombinant protein used for in vitro assays. Although results of the enzymatic assays were inconclusive, bioinformatics analyses of putative catalytic residues favor functional involvement in fatty alcohol dehydrogenation, rather than in nitrile lyation. This prediction suggests that HTH might be functionally distinct from the closely-related enzyme, mandelonitrile lyase. In addition, coexpression analysis showed that HTH is coexpressed not only with genes involved in cutin synthesis but also with those modulated by pathogens and stress. Although results also pointed towards an association between HTH and defense/stress response, how this association might be linked to genome instability observed in hth mutants is discussed

SASMU: boost the performance of generalized recognition model using synthetic face dataset

Nowadays, deploying a robust face recognition product becomes easy with the development of face recognition techniques for decades. Not only profile image verification but also the state-of-the-art method can handle the in-the-wild image almost perfectly. However, the concern of privacy issues raise rapidly since mainstream research results are powered by tons of web-crawled data, which faces the privacy invasion issue. The community tries to escape this predicament completely by training the face recognition model with synthetic data but faces severe domain gap issues, which still need to access real images and identity labels to fine-tune the model. In this paper, we propose SASMU, a simple, novel, and effective method for face recognition using a synthetic dataset. Our proposed method consists of spatial data augmentation (SA) and spectrum mixup (SMU). We first analyze the existing synthetic datasets for developing a face recognition system. Then, we reveal that heavy data augmentation is helpful for boosting performance when using synthetic data. By analyzing the previous frequency mixup studies, we proposed a novel method for domain generalization. Extensive experimental results have demonstrated the effectiveness of SASMU, achieving state-of-the-art performance on several common benchmarks, such as LFW, AgeDB-30, CA-LFW, CFP-FP, and CP-LFW.Comment: under revie