Lemon grass essential oil improves Gladiolus grandiflorus postharvest life by modulating water relations, microbial growth, biochemical activity, and gene expression.

Gladiolus (Gladiolus grandiflorus Andrews) is a high-valued bulbous cut flower. However, the shorter postharvest life of the gladiolus, limits its marketing and commercial value. In the present investigation, the effect of lemon grass (LG) essential oil as an antimicrobial agent was studied towards increasing the vase life of gladiolus. The results revealed that as compared to control (distilled water), treatment with a lower concentration of 5 µL L-1 LG essential oil prolonged the vase life of gladiolus up to 11 days (d). Scanning Electron Microscope (SEM) observation indicated that the sample treated with 5 µL L-1 LG essential oil showed intact vasculature, suggesting reduced microbial blockage at the stem end which was further corroborated by microbial count. Biochemical analysis suggested an increased level of total soluble sugars, carotenoid content, lower MDA accumulation, and higher activity of antioxidant enzymes in LG treated flowers. Moreover, transcripts levels of genes associated with senescence viz., GgCyP1 and GgERS1a were downregulated, while expression of GDAD1 and antioxidant genes such as GgP5C5, GgPOD 1, GgMnSOD, and GgCAT1 were upregulated in LG treated cut spikes as compared to control. Among various treatments we have concluded that, the vase life of the gladiolus cut spike was improved along with the relative fresh flower weight and diameter of flower at the lower dose of 5 µL L-1 LG oil in the vase solution. Thus, LG oil as an eco-friendly agent has the potential to extend the postharvest life of cut flowers.

Unravelling the carbon and sulphur metabolism in coastal soil ecosystems using comparative cultivation-independent genome-level characterisation of microbial communities.

Bacterial autotrophy contributes significantly to the overall carbon balance, which stabilises atmospheric CO2 concentration and decelerates global warming. Little attention has been paid to different modes of carbon/sulphur metabolism mediated by autotrophic bacterial communities in terrestrial soil ecosystems. We studied these pathways by analysing the distribution and abundance of the diagnostic metabolic marker genes cbbM, apsA and soxB, which encode for ribulose-1,5-bisphosphate carboxylase/oxygenase, adenosine phosphosulphate reductase and sulphate thiohydrolase, respectively, among different contrasting soil types. Additionally, the abundance of community members was assessed by quantifying the gene copy numbers for 16S rRNA, cbbL, cbbM, apsA and soxB. Distinct compositional differences were observed among the clone libraries, which revealed a dominance of phylotypes associated with carbon and sulphur cycling, such as Gammaproteobacteria (Thiohalomonas, Allochromatium, Chromatium, Thiomicrospira) and Alphaproteobacteria (Rhodopseudomonas, Rhodovulum, Paracoccus). The rhizosphere soil was devoid of sulphur metabolism, as the soxB and apsA genes were not observed in the rhizosphere metagenome, which suggests the absence or inadequate representation of sulphur-oxidising bacteria. We hypothesise that the novel Gammaproteobacteria sulphur oxidisers might be actively involved in sulphur oxidation and inorganic carbon fixation, particularly in barren saline soil ecosystems, suggesting their significant putative ecological role and contribution to the soil carbon pool.