Ishwar Chandra Mohanty

Uptake of excess iron by lowland rice plants causes iron toxicity, which is a major problem in the affected areas. This study investigated molecular diversity, genetic structure, and marker–trait associations for tolerance to iron toxicity in a panel of germplasm lines using microsatellite markers. The studied population showed a moderate to high degree of genetic diversity, as revealed by the estimated molecular diversity parameters and principal component, cluster and box plot analyses. The landraces Mahipal, Dhusura, Dhabalabhuta, Champa, Sunapani and Kusuma were identified as suitable for cultivation in the areas affected by high iron levels. The landraces Dhusura, Kusuma, Kendrajhali, Ranisaheba, Panjabaniswarna, Mahipal, Dhinkisiali, Champa, Kalamara and Ratanmali, which showed low scores for tolerance, were considered good donors for iron toxicity tolerance improvement programs. Utilizing STRUCTURE software, a total of four genetic structure groups were detected in the panel germplasm of lines. These structural subgroups exhibited good correlations among their members for iron toxicity tolerance and other yield-related traits. Marker–trait association analysis validated the reported iron toxicity tolerance QTLs qFeTox 4.2 and qFeTox 4.3, which are useful for marker-assisted improvement. A new QTL, qFeTox 7.1, located on chromosome 7, was detected as controlling iron toxicity tolerance in rice.

Fresh, shade-dried and powdered samples of leaf, stem and root of Chitrak (Plumbago zeylanica L) were subjected to fractional distillation in a Soxhlet apparatus using four organic solvents. Chloroform, acetone and ethanol extracts from root of Plumbago showed higher zone of inhibition of 22.66±1.52, 21.5±1.29 and 16.5±1.29 mm and minimum inhibitory concentration (MIC) of 1.0, 10.0 and 10.0 μg/ml, respectively against Escherichia coli. Root and leaf extracts by ethanol, chloroform and acetone showed higher antibacterial activity against E. coli as compared to standard Kanamycin (MIC-100 μg/ml). The high performance thin layer chromatography (HPTLC) fingerprints were used for the quantitation of two bioactive markers: gibberellic acid and quinol R in the plant powder of different organs. Maximum content of gibberellic acid was found in acetone extract of the root (59.74%, Rf 0.79) followed by methanol root extract (53.01%). HPTLC provides a chromatographic fingerprint of phytochemicals and is suitable for confirming the identity and purity of medicinal plant raw materials. Key words: Plumbago zeylanica, antimicrobial property, bioactive compound, kanamycin, Escherichia coli, high performance thin layer chromatography (HPTLC), phytochemical fingerprint.