Plant Growth Promoting Activity and Metal Tolerance of Bacteria Isolated from Rhizosphere of the Orchid Epipactis atrorubens Growing on Serpentine Substrates of the Middle Urals

В статье представлены данные, полученные при изучении бактерий, выделенных из ризосферы орхидеи Epipactis atrorubens (Hoffm.) Besser. Проведен сравнительный анализ некоторых морфологических, физиологических и биохимических характеристик ризобактерий растений, произрастающих в двух биотопах на серпентинитовых породах: в естественном лесном фитоценозе (фоновый участок) и на отвале после добычи асбеста (Свердловская область, Средний Урал). Оценка ростстимулирующей (PGP) активности выделенных штаммов не показала достоверных различий между исследованными участками по способности ризобактерий к синтезу индолил‑3-уксусной кислоты (ИУК) и солюбилизации фосфатов. Однако доля изолятов, способных к азотфиксации, была выше в ризосфере E. atrorubens, произрастающего на отвале, по сравнению с фоновым местообитанием. Устойчивость изолятов к тяжелым металлам оценивали по максимальной концентрации металла (400, 600 и 1000 мг/л соответственно для Ni, Cu и Zn), при которой отмечался рост бактерий. Показано, что ризобактерии с отвала оказались более устойчивыми к повышенным концентрациям металлов по сравнению с естественным лесным фитоценозом. На основе молекулярно-генетического анализа изолятов с наиболее выраженной PGP‑активностью (ИУК >1,0 мг/л; PO4 3- >50,0 мг/л) обнаружено сходство между изученными местообитаниями по родовой принадлежности ризобактерий E. atrorubens: выделенные штаммы принадлежали преимущественно к родам Buttiauxella и Pseudomonas. В модельных экспериментах протестирована ростстимулирующая способность четырех отобранных штаммов на семенах циннии. Инокуляция семян Pseudomonas sp. и Buttiauxella sp. не оказывала значимого влияния на их всхожесть, однако Buttiauxella sp. способствовала увеличению длины проростков в сравнении с контролем (в среднем на 25 %). Сделано предположение, что отобранные изоляты ризобактерий E. atrorubens, благодаря их ростстимулирующей активности и металлоустойчивости, могут способствовать натурализации орхидеи на техногенно нарушенной территорииThe article presents data obtained in the study of bacteria isolated from the rhizosphere of the orchid Epipactis atrorubens (Hoffm.) Besser. Analysis was carried out to compare some morphological, physiological, and biochemical characteristics of plant rhizobacteria growing on serpentine rocks in two biotopes: in the natural forest community (control habitat) and on the asbestos mine dump (the Sverdlovsk region, Middle Urals). An assessment of the plant growth promoting (PGP) activity of the isolated strains did not show significant differences in the ability of rhizobacteria to synthesize indol‑3-acetic acid (IAA) and solubilize phosphates between the study sites. However, the proportion of isolates capable of nitrogen fixation was higher in the rhizosphere of E. atrorubens growing on the dump compared to the control habitat. The tolerance of isolates to heavy metals was assessed by the maximum metal concentration (400, 600, and 1000 mg/L, respectively, for Ni, Cu, and Zn) at which bacterial growth was observed. Rhizobacteria from the dump were found to be more resistant to elevated concentrations of metals compared to their counterparts from the natural forest community. The molecular genetic analysis of isolates with the highest PGP‑activity (IAA >1.0 mg/L; PO4 3- >50.0 mg/L) revealed that most of the E. atrorubens rhizobacteria in both habitats belonged to the genera Buttiauxella and Pseudomonas. In model experiments, the PGP ability of four selected strains was tested on zinnia seeds. Seed inoculation with Pseudomonas sp. and Buttiauxella sp. did not have any significant effect on their germination; however, Buttiauxella sp. contributed to the increase in the length of seedlings compared with the control (by 25 %, on average). It has been suggested that the selected isolates of E. atrorubens rhizobacteria, due to their growth promoting activity and metal tolerance, can facilitate naturalization of the orchid in an industrially disturbed are

Polygenic Risk Scores for Prediction of Breast Cancer and Breast Cancer Subtypes

Stratification of women according to their risk of breast cancer based on polygenic risk scores (PRSs) could improve screening and prevention strategies. Our aim was to develop PRSs, optimized for prediction of estrogen receptor (ER)-specific disease, from the largest available genome-wide association dataset and to empirically validate the PRSs in prospective studies. The development dataset comprised 94,075 case subjects and 75,017 control subjects of European ancestry from 69 studies, divided into training and validation sets. Samples were genotyped using genome-wide arrays, and single-nucleotide polymorphisms (SNPs) were selected by stepwise regression or lasso penalized regression. The best performing PRSs were validated in an independent test set comprising 11,428 case subjects and 18,323 control subjects from 10 prospective studies and 190,040 women from UK Biobank (3,215 incident breast cancers). For the best PRSs (313 SNPs), the odds ratio for overall disease per 1 standard deviation in ten prospective studies was 1.61 (95%CI: 1.57-1.65) with area under receiver-operator curve (AUC) = 0.630 (95%CI: 0.628-0.651). The lifetime risk of overall breast cancer in the top centile of the PRSs was 32.6%. Compared with women in the middle quintile, those in the highest 1% of risk had 4.37- and 2.78-fold risks, and those in the lowest 1% of risk had 0.16- and 0.27-fold risks, of developing ER-positive and ER-negative disease, respectively. Goodness-of-fit tests indicated that this PRS was well calibrated and predicts disease risk accurately in the tails of the distribution. This PRS is a powerful and reliable predictor of breast cancer risk that may improve breast cancer prevention programs.NovartisEli Lilly and CompanyAstraZenecaAbbViePfizer UKCelgeneEisaiGenentechMerck Sharp and DohmeRocheCancer Research UKGovernment of CanadaArray BioPharmaGenome CanadaNational Institutes of HealthEuropean CommissionMinistère de l'Économie, de l’Innovation et des Exportations du QuébecSeventh Framework ProgrammeCanadian Institutes of Health Researc

BIOFERTILIZER BASED ON SILICATE SOLUBILIZING BACTERIA IMPROVES PHOTOSYNTHETIC FUNCTION OF BRASSICA JUNCEA

Usage of biofertilizers is one of the important components of integrated nutrientmanagement, as they are renewable source of plant nutrients, ecologically safecompared to chemical fertilizers and cost effective. Silicate solubilizing bacteria(SSB) can play an efficient role not only in solubilizing insoluble forms of silicatesbut also potassium and phosphates, hence increasing soil fertility and therebyenhancing plant productivity. The aim of this study was to investigate the influenceof SSB-enriched biofertilizer on the structural and functional parameters ofphotosynthetic apparatus of Brassica juncea (L.) Czern. The pure culture of SSBwas isolated from the clay substrate, cultivated on Zak–Alexandrov medium andidentified as Bacillus sp. To obtain the biofertilizer, SSB culture (0.6*108 cfu mL-1)was mixed with steriled peat (1:1, v/w) and dried at 35–40°C. Plants were grownfrom seeds during two months in the pots with adding SSB-enriched biofertilizer tothe mixture of clay and soil (1:10, w/w). The clay substrate plus peat without SSBwas used as a control. It was found that addition of SSB-enriched biofertilizer toclay substrate significantly increased the content of total nitrogen, phosphorus andpotassium in the leaves of B. juncea. The thickness of mesophyllic layer and thenumber of mesophyll cells were increased on average by 24 %. It was correlatedwith a sharp increase of photosynthetic pigment content and CO2 uptake (1.5–2.0times). We can conclude that SSB-enriched biofertilizer improves thephotosynthetic function of B. juncea

Biofertilizer Based on Biochar and Metal-Tolerant Plant Growth Promoting Rhizobacteria Alleviates Copper Impact on Morphophysiological Traits in Brassica napus L.

Metal tolerant plant growth-promoting (PGP) rhizobacteria are promising for enhancing plant productivity under copper (Cu) stress. Present pot scale experiment was conducted on Brassica napus L. to check the efficiency of rhizobacteria isolated from the rhizosphere of Tussilago farfara L. growing on Cu-contaminated soils. Out of fifty Cu tolerant strains, three isolates which showed multiple PGP traits such as indole-3-acetic acid (IAA) synthesis, phosphate (PS) solubilization, siderophore and ammonia production were identified preliminarily by morphological and physiological characteristics followed by 16S rRNA gene sequencing. The best Bacillus altitudinis strain TF16a which showed IAA: 15.5 mg L−1, PS: 215 mg L−1, siderophore halo zone ratio of 3.0 with high ammonia production was selected to prepare a biochar-based biofertilizer (BF). Seedling test showed maximum growth of B. napus shoot and root in presence of 5% of BF and this concentration was selected for further experiment. The pot experiment included four treatments: control (soil), 100Cu (100 mg Cu kg−1 soil), 5%BF (v/v), and 5%BF+100Cu, which were carried out for 30 days, after which the morphological, physiological, and biochemical parameters of B. napus were studied. The Cu treatment caused its accumulation in shoot and root up to 16.9 and 30.4 mg kg−1 DW, respectively, and increased malondialdehyde (MDA) content by 20%. Application of BF with copper led to the decrease in the Cu accumulation by 20% for shoot and 28% for root while MDA content was the same as in the control. Both treatments of BF with and without Cu increased chlorophyll a and b content by 1.3 times on average as well as non-enzymatic antioxidants such as soluble phenolic compounds (1.3 times) and free proline (1.6 times). Moreover, BF + Cu led to the increase in the biomass of shoot and root by 30 and 60%, respectively, while there was no significant effect on the growth characteristics of plants after the addition of BF without Cu. The study elucidates that BF based on B.altitudinis strain TF16a and biochar can be a promising bioformulation which could increase rapeseed growth under the moderate Cu concentration in soil