Regeneration via somatic embryogenesis from leaf basal segments and genetic transformation of bread and emmer wheat by particle bombardment

Direct gene transformation methods such as microprojectile bombardment have been successfully employed for obtaining transgenics in cereals in general and wheat in particular. As success of any transformation strategy depends largely upon the regeneration capability of the target explant, the present investigation employs leaf basal segments to achieve high regeneration response via somatic embryogenesis. Basal segments of 5-day-old seedlings of T. aestivum var. CPAN1676 and T. dicoccum var. DDK1001 were cultured on callusing medium for 3 weeks at 26 ± 1 °C, discontinuous light followed by a culture period of 15 days at 21 ± 1 °C in continuous light. The calli were then transferred to auxin-free medium for regeneration in discontinuous light at 26 ± 1 °C. Regeneration via somatic embryogenesis was observed within 2 weeks in T. aestivum var. CPAN1676 and T. dicoccum var. DDK1001 (68 and 82%, respectively). This embryogenic calli were employed further to obtain hygromycin resistance by particle bombardment in T. aestivum and T. dicoccum. A transformation efficiency of 8.6, 7.5 and 4.9% was obtained in T. aestivum var. CPAN1676, PBW343 and T. dicoccum DDK1001, respectively. Presence of the transgene hptII (hygromycin) in T ₀ plants was confirmed by Southern hybridization.     

Shift in Cyanobacteria Community Diversity in Hot Springs of India

Two ecologically distinct tropical sulfur-rich alkaline hot springs, Taptapani at 48°C harboring mesophiles and Atri at 58°C comprising thermophiles situated in the Eastern Ghats foothills of India, differ in their geochemical conditions, and provide an interesting platform to unravel the eco-physiological reasons behind the differential cyanobacterial diversity. The predominance of mesophilic Arthronema (83.81%) in Taptapani and shifting predominance of thermophilic Leptolyngbya (96.25%) in Atri as discovered through 16S rRNA gene Illumina sequencing of their metagenomics DNA as a function of temperature are the intriguing features of the present study. Differential presence of the cyanobacterial community at the phylum level in these two hot springs was found to be correlated with the unequal coexistence of Chloroflexi, Taptapani the non-cyanobacteria members and the possible influence of physiochemical parameters including temperature. Variation in cyanobacterial diversity and composition of these hot springs as revealed through sequence analysis were also evinced by respective differences in richness, evenness, and Shannon diversity indices.     

Horizontal gene transfer and bacterial diversity

Bacterial genomes are extremely dynamic and mosaic in nature. A substantial amount of genetic information is inserted into or deleted from such genomes through the process of horizontal transfer. Through the introduction of novel physiological traits from distantly related organisms, horizontal gene transfer often causes drastic changes in the ecological and pathogenic character of bacterial species and thereby promotes microbial diversification and speciation. This review discusses how the recent influx of complete chromosomal sequences of various microorganisms has allowed for a quantitative assessment of the scope, rate and impact of horizontally transmitted information on microbial evolution.