Arpita Moharana

Vitex negundo L. is a significant indigenous medicinal plant with diverse therapeutic potentials owing to its rich reservoir of bioactive compounds including sitosterol, vitexoside, agnuside, isovitexin and vitexin which are predominantly present in the root. To induce hairy roots, explants of V. negundo L. were transformed using two strains of Rhizobium rhizogenes: MTCC 532 and MTCC 2364. Among them, the MTCC 2364 strain exhibited the highest transformation efficiency (94.44%). Genetic transformation of the induced hairy roots was confirmed by PCR amplification using primers specific for the rolB and rolC genes and man2 opine primers. Hairy root culture in MS liquid medium at 90 RPM shaking conditions showed an overall higher growth index (9.47 fresh weight in 18–21 months). The vitexin compound was verified and quantified in both hairy roots and wild-type roots by HPLC analysis, revealing a higher concentration in hairy roots (0.49 mg/g Dry Weight) than in the wild-type roots (0.065 mg/g Dry Weight). Furthermore, the multi-elemental analysis using an EDXRF spectrometer revealed the trace elemental analysis in both hairy roots and wild-type roots. To date this is the first report confirming the production of vitexin in hairy root culture of V. negundo which, represents an efficient and economical approach for the large-scale production of such secondary metabolites. Graphical abstract

Mangrove systems are major blue-carbon reservoirs, storing 4.4 to 11.7 petagrams of organic carbon globally and supporting diverse microalgal communities that drive primary productivity and coastal carbon cycling. The Sundarban, one of the world’s largest (3,629.57 km²) mangrove-dominated coastal systems, holds a substantial carbon stock (26.62 Tg). Rising salinity and anthropogenic pressure are altering the diversity of microalgal communities, highlighting the importance of identifying resilient taxa capable of sustaining carbon fixation. To address this need, we conducted whole-genome metagenomic profiling of degraded mangrove soils. The data revealed six dominant microalgal taxa adapted to prevailing salinity and nutrient stress. These six taxa were subsequently isolated from the same habitats, and a 16-day ambient CO₂ (420 ppm) screening was undertaken to evaluate the specific growth rate and biomass gain of the algae. Among them, three physiologically resilient strains Chlorella sp., Limnospira platensis, and Leptolyngbya boryana were selected for controlled CO₂-enrichment concentrations (0.04%, 0.05%, 0.20%, 10%) to mimic future climate change scenarios. Among those microalgae, the Leptolyngbya boryana showed the highest biomass yield (1.31 g L⁻¹), carbon content (0.52 g C g⁻¹ dry weight), and CO₂-fixation rate (up to 149 mg CO₂ L⁻¹ d⁻¹). Metagenomic analysis further identified that L. boryana possessed the strongest representation of carbon-fixation pathways like Calvin-Benson-Bassham (CBB) cycle and the reductive TCA (rTCA) cycle, regulated by enriched key genes such as cbbL, cbbS, gap2, zwf, and accC. Therefore, this result positions L. boryana as a promising microalgal candidate for carbon sequestration in future CO₂-rich environments under saline coastal ecology.

Vitex negundo L. is an aromatic, woody, blooming shrub in the Lamiaceae family which can grow into a small tree. Traditionally, V. negundo root has been used to cure diabetes, colic, boils, leprosy, and rheumatism. Keeping the importance of its roots in mind, an attempt has been taken for development of a protocol for efficient hairy root proliferation system. The Agrobacterium rhizogenes strains (MTCC 532 and MTCC 2364) were used for hairy root induction. For A. rhizogenes infection, both in vitro and in vivo leaves as well as internodes were used as explant. In vitro leaves and internodal explants were obtained by the inoculation of matured nodal segments on the optimum medium [MS + 2.0 mg/L N6-Benzylaminopurine (BAP)] with c.a. 91.6% shoot regeneration and an average of 8.1 shoots per explants. In vitro leaf showed best hairy root induction followed by in vitro internode on ½ MS medium augmented with acetosyringone. Highest transformation efficiency was achieved using MTCC 2364 strain, while no transformation was observed in MTCC 532 strain. Different factors affecting transformation including co-cultivation period, infection time and optical density (O.D.) value were standardized. The highest efficacy, 88.8% hairy root induction was observed in in vitro leaves infected by MTCC 2364 for 60 minutes infection time with an O.D. value of 0.29 maintained over a 44-48 hours of co-cultivation period. The prescribed protocol may be used as a reference for development of industrial scale hairy root production for bioactive compound located in root of V. negundo.

Reeta is a popular late-maturing high-yielding rice variety recommended for cultivation in the eastern Indian states. The cultivar is highly sensitive to submergence stress. Phosphorus deficiency is an additional constraint for realizing high yield. The quantitative trait loci (QTLs), Sub1, for submergence and Pup1 for low phosphorus stress tolerance along with narrow-grained trait, GW5 were introgressed into the variety from the donor parent, Swarna-Sub1 through marker-assisted breeding. In addition, phenotypic selections for higher panicle weight, grain number, and spikelet fertility were performed in each segregating generation. Foreground selection detected the 3 target QTLs in 9, 8 and 7 progenies in the BC₁F₁, BC₂F₁, and BC₃F₁ generation, respectively. Recurrent parent’s genome recovery was analyzed using 168 SSR polymorphic markers. The foreground analysis in 452 BC₃F₂ progenies showed five pyramided lines in homozygous condition for the target QTLs. No donor fragment drag was noticed in the Sub1 and GW5 QTLs carrier while a segmentwas observed in the Pup1 carrier chromosome. The developed lines were higher yielding, had submergence, and had low phosphorus stress-tolerance alongwith similar to the recipient parent in the studied morpho-quality traits. A promising pyramided line is released in the name of Reeta-Panidhan (CR Dhan 413) for the flood-prone areas of Odisha state.

Antioxidant-rich rice is a cheaper way to solve stress-related disorders and other health benefits for the global rice-eating population. Five antioxidant traits, namely, superoxide dismutase, flavonoids, anthocyanins, γ-oryzanol and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) activity were mapped using a representative panel population through association mapping. Potential landraces carrying multiple antioxidant compounds were identified from the population. The population represented four genetic groups and correspondence for presence of antioxidants traits in each group was noticed. The population showed linkage disequilibrium for the studied traits based on the Fst values. A total of 14 significant marker–trait associations were detected for these antioxidant traits. The study validated the QTLs, qANC3 and qPAC12-2 for anthocyanin content and qAC12 for ABTS activity will be useful in marker-assisted breeding. Eleven QTLs such as qTAC1.1 and qTAC5.1 controlling anthocyanin content, qSOD1.1, qSOD5.1 and qSOD10.1 for superoxide dismutase (SOD), qTFC6.1, qTFC11.1 and qTFC12.1 for total flavonoids content (TFC), qOZ8.1 and qOZ11.1 for γ-oryzanol (OZ) and qAC11.1 for ABTS activity were detected as novel loci. Chromosomal locations on 11 at 45.3 cM regulating GO, TFC and TAC, and on the chromosome 12 at 101.8 cM controlling TAC and ABTS activity, respectively, were detected as antioxidant hotspots.

Bacterial blight (BB) disease caused by Xanthomonas oryzae pv. oryzae is a major biotic constraint on obtaining higher grain yields in rice. Marker-assisted backcross breeding (MABB) was performed by the pyramiding of Xa4, xa5, xa13 and Xa21 resistance genes in the popular variety, Ranidhan. A foreground selection in BC₁F₁, BC₂F₁, and BC₃F₁ progenies detected all the target genes in 12, 7 and 16 progenies by using the closely linked markers from a population size of 446, 410, and 530, respectively. The BB-positive progenies carrying the target genes with a maximal similarity to the recipient parent was backcrossed in each backcross generation. A total of 1784 BC₃F₂ seeds were obtained from the best BC₃F₁ progeny. The screening of the BC₃F₂ progenies for the four target genes resulted in eight plants carrying all the four target genes. A bioassay of the pyramided lines conferred very high levels of resistance to the predominant isolates of bacterial blight disease. In addition, these pyramided lines were similar to Ranidhan in 16 morpho-quality traits, namely, plant height, filled grains/panicle, panicles/plant, grain length, grain breadth, grain weight, milling, head rice recovery, kernel length after cooking, water uptake, the volume expansion ratio, gel consistency, alkali-spreading value, and the amylose content.