Employing Illumina Hiseq whole genome metagenome sequencing approach, we studied the impact of Trichoderma harzianum on altering the microbial community and its functional dynamics in the rhizhosphere soil of black pepper (Piper nigrum L.). The metagenomic datasets from the rhizosphere with (treatment) and without (control) T. harzianum inoculation were annotated using dual approach, i.e., stand alone and MG-RAST. The probiotic application of T. harzianum in the rhizhosphere soil of black pepper impacted the population dynamics of rhizosphere bacteria, archae, eukaryote as reflected through the selective recruitment of bacteria [Acidobacteriaceae bacterium (p = 1.24e−12), Candidatus koribacter versatilis (p = 2.66e−10)] and fungi [(Fusarium oxysporum (p = 0.013), Talaromyces stipitatus (p = 0.219) and Pestalotiopsis fici (p = 0.443)] in terms of abundance in population and bacterial chemotaxis (p = 0.012), iron metabolism (p = 2.97e−5) with the reduction in abundance for pathogenicity islands (p = 7.30e−3), phages and prophages (p = 7.30e−3) with regard to functional abundance. Interestingly, it was found that the enriched functional metagenomic signatures on phytoremediation such as benzoate transport and degradation (p = 2.34e−4), and degradation of heterocyclic aromatic compounds (p = 3.59e−13) in the treatment influenced the rhizosphere micro ecosystem favoring growth and health of pepper plant. The population dynamics and functional richness of rhizosphere ecosystem in black pepper influenced by the treatment with T. harzianum provides the ecological importance of T. harzianum in the cultivation of black pepper.

The study investigated the reduction in metalloid uptake at equimolar concentrations (~53.3 μM) of As(III) and As(V) in contrasting pair of rice seedlings by pretreating with H 2 O 2 (1.0 μM) and SA (1.0 mM). Results obtained from the contrasting pair (arsenic tolerant vs. sensitive) of rice seedlings (cv. Pant Dhan 11 and MTU 7029, respectively) shows that pretreatment of H 2 O 2 and H 2 O 2 + SA reduces As(V) uptake significantly in both the cultivars, while no reduction in the As(III) uptake. The higher growth inhibition, higher H 2 O 2 and TBARS content in sensitive cultivar against As(III) and As(V) treatments along with higher As accumulation (~1.2 mg g −1 dw) than in cv. P11, unravels the fundamental difference in the response between the sensitive and tolerant cultivar. In the H 2 O 2 pretreated plants, the translocation of As increased in tolerant cultivar against AsIII, whereas, it decreased in sensitive cultivar both against AsIII and AsV. In both the cultivars translocation of Mn increased in the H 2 O 2 pretreated plants against As(III), whereas, the translocation of Cu increased against As(V). In tolerant cultivar the translocation of Fe increased against As(V) with H 2 O 2 pretreatment whereas, it decreased in the sensitive cultivar. In both the cultivars, Zn translocation increased against As(III) and decreased against As(V). The higher level of H 2 O 2 and SOD (EC 1.15.1.1) activity in sensitive cultivar whereas, higher, APX (EC 1.11.1.11), GR (EC 1.6.4.2) and GST (EC 1.6.4.2) activity in tolerant cultivar, also demonstrated the differential anti-oxidative defence responses between the contrasting rice cultivars.