Plant hormones and the circadian rhythm have been implicated in coordinated control of isoprene emission in plants. To gain insights into the signalling networks, foliar application of plant hormones was conducted in a native emitter, Ficus septica.Spraying of 50 μM jasmonic acid (JA) gradually decreased isoprene emission by 88% compared with initial levels within 5 days, and emission increased after relief from JA application. We further explored the molecular regulatory mechanism of isoprene emission by analysing photosynthetic rate, gene expression of 2-C-methyl-D-erythrytol 4-phosphate (MEP) pathway, hormone signalling and circadian rhythm processes, and metabolite pool sizes of MEP pathway. Results show that isoprene emission strongly correlated with isoprene synthase (IspS) gene expression and IspS protein levels over the period of JA treatment, indicating transcriptional and possible translational modulation of IspS by JA. Application of JA coordinately modulated genes in the auxin, cytokinin (CK), and circadian rhythm signal transduction pathways. Among the transcriptional factors analysed, MYC2 (JA) and LHY (circadian clock) negatively correlated with isoprene emission. Putative cis-elements predicted on IspS promoter (G-box for MYC2 and circadian for LHY) supports our proposal that isoprene emission is regulated by coordinated transcriptional modulation of IspS gene by phytohormone and circadian rhythm signalling.

The present study was conducted in the experimental farm, Sher-e-Bangla Agricultural University (SAU), Dhaka during July 2013-December2013. The analysis of variance revealed significant deviation for all the characters studied and indicated the existence of variation among thegenotypes. The PCV values were slightly higher than the respective GCV values for all the characters except unfilled grains per panicleindicating that the characters were less influenced by the environment. Total tillers per plant, effective tillers per plant, filled grains per panicle,unfilled grains per panicle and yield per plant showed high heritability coupled with high genetic advance percentage of mean which indicatedthe preponderance of additive gene action and such characters could be improved through selection. High heritability along with low geneticadvance as percentage of mean was found for plant height, days to 50% flowering, panicle length, days to maturity and thousand grains weightwhich indicated the non additive gene action for expression of these characters. Considering the genetic parameters and other agronomicperformances, the genotypes Special from AL-29, AL-36, PP-4B(i), AL-17(iii)B, AL-17(iii), AL-17(ii)A, Special from-129, Special from17(iv), AL-44(i), AL-17, Special from AL-36(D), PP-48, IR-25B, Special from AL-33, IR-25B (Tall), P-5B (ii) might be considered betterparents for future hybridization programme.DOI: http://dx.doi.org/10.3126/ijasbt.v3i1.11896    Int J Appl Sci Biotechnol, Vol. 3(1): 73-79

Forty eight genotypes of tomato were evaluated for yield contributing characters to observe their associations and direct and indirect effect on yield. Character association analysis among yield and yield contributing characters revealed that in most of cases the genotypic correlation coefficient was higher than the respective phenotypic correlation coefficients. This indicated that the suppressive effect of the environment modified the phenotypic expression of these characters by reducing phenotypic correlation values. Also, narrow difference between phenotypic and genotypic correlation coefficient was noticed for almost all the pairs of characters studied showing that masking or modifying effects of the environment was little indicating the presence of an inherent association among these characters. Fruit/cluster showed non-significant positive association with yield/plant at genotypic and phenotypic level but individual weight of fruit had significant negative association at phenotypic level with yield/plant. Path coefficient analysis revealed that no. of fruit/cluster had the highest positive direct effects on fruit yield/plant suggesting their importance while imposing selection for correlation of yield in tomato.Int J Appl Sci Biotechnol, Vol 3(2): 223-226 DOI: http://dx.doi.org/10.3126/ijasbt.v3i2.12421