ISA

005747 Tewari G;Soni M K;Kumar R;Kaur S;Sharma Y K (Botany Dep, Lucknow Univ, Lucknow-226 007, Email: tewarigopal@gmail.com) : Combinatorial effect of low temperature and IAA on flowering responses, metabolites and enzymes in Cucumis sativus. Res Envir Life Sci 2010, 3(1), 33-40.

The combined effect of IAA and low temperature exposure at the seed germination stage, on the process of floral induction in cucumber was analyzed in this experiment. The low temperature exposure to the seeds decreased the days to anthesis of both male and female flowers to 43.25 and 52.25 respectively. Similarly, the average nodal position bearing first male as well as female flower also decreased as compared to control on providing low temperature and/or IAA, alone or in combination at seed germination stage, the reduction being more noteworthy when IAA and low temperature were given in combination. The total No. of female flowers formed, however, increased with the application of low temperature and IAA and, consequently, the ratio of male flowers to female flowers decreased with the increasing concentration of IAA, the reduction being more when low temperature was provided with IAA. The sucrose content was 240.0 μmol/gm fresh weight in control which declined to 237.5, 235.0 and 233.7 μmol g-1 fresh weight in plants which were treated with 25, 50 and 100 mg L-1 IAA respectively at seed germination stage. Exposure to low temperature, however, increased the sucrose content. The application of IAA, on the other hand, resulted in the increase in the starch content during both pre-flowering stage as well as flowering stage. The application of IAA also resulted in a gradual increase in the protein content, and this increase was more when IAA and low temperature were given in combination. However, in contrast to starch, the protein contents were found to be increased when plants experienced a shift from pre-flowering to flowering stage. Application of IAA at seed germination stage, however, decreased the activity of sucrose synthase, the decline being proportional to the concentration of IAA applied. Activity of acid invertase, though, showed a tendency just reverse to that of sucrose synthase. At both, the pre-flowering and flowering stages, low temperature exposure of seeds resulted in a decline in the activity of acid invertase while application of IAA at seed germination stage caused an increase in the activity of the enzyme in a concentration dependent manner. The activity of IAA oxidase at pre-flowering stage was significantly lowered in all the treatments as compared to control with the reduction in the activity being proportional to the concentration of IAA applied. A reduction in the activity of IAA oxidase was observed in all the plants when they experienced a shift from pre-flowering to flowering stage. Polyphenol oxidase, though, showed a trend just opposite to that shown by IAA oxidase. At flowering stage, again just opposite to the IAA oxidase, the activity of polyphenol oxidase increased from that in pre-flowering stage in all the plants. The highest activity during flowering stage was recorded in plants that were raised from seeds treated with 100 mg L-1 IAA at low temperature (0.252 DOD g-1 fresh weight). There was, however, not significant alteration in the peroxidase activity in all the treatments over control; though the peroxidase activity increased slightly on the application of IAA and low temperature as compared to control at both pre-flowering and flowering stages.

Effect of IAA on flowering responses, metabolites and enzymes in Cucumis sativus

Tewari G;Soni M K;Kaur S;Sharma Y K

005746 Tewari G;Soni M K;Kaur S;Sharma Y K (Botany Dep, Lucknow Univ, Lucknow-226 007, Email: tewarigopal@gmail.com) : Effect of IAA on flowering responses, metabolites and enzymes in Cucumis sativus. Res Envir Life Sci 2009, 2(4), 219-22.

Seeds of cucumber,Cucumis sativus L., variety Jyoti Green Long, were exposed in different concentrations of IAA (0 - as control, 25, 50 and 100 mg L-1), for varying durations (24, 48 and 72 hr). After two weeks five seedlings from each petridish were transplanted in pots. The days to anthesis were highest in control for both male and female flowers, which gradually reduced as the increasing concentration of IAA was applied. Similarly, the average nodal position bearing first flower was highest in control which consistently decreased with increasing concentration and duration of IAA treatment. The total No. of male flowers showed a declining trend with the increasing application of IAA. However, percentage of pollen sterility were increased in plants raised from seeds that were applied with 25, 50 and 100 mg L-1 IAA for 24 hr respectively. Number of female flowers formed, was markedly increased over control with the elevation of IAA concentration. Total sucrose content during pre-flowering stage was highest (240.0 μmol g-1 fresh weight) in control but on treatment with IAA it decreased to significantly lower value of 197.5 μmol g-1 fresh weight in plants grown from seeds treated with 100 mg L-1 IAA for 72 hr. There was a decline in the sucrose content as well when flowering took place in all the plants. The highest concentration of starch at pre-flowering stage was observed in plants raised from seeds that were given 100 mg L-1 IAA for 72 hr (0.350 mg g-1 fresh weight), a significant difference from control. The starch content, however, was lowered at the flowering stage as compared to pre-flowering stage in all the plants. Total protein content, also, increased over control with the increasing concentration and duration of IAA application. During pre-flowering stage the sucrose synthase activity consistently decreased as compared to control with the increasing concentration of IAA. Activity of acid invertase, though, showed a trend just opposite to that of sucrose synthase. At pre-flowering acid invertase activity was 104.24 μmol g-1 fresh weight in control which increased to 116.25 μmol g-1 fresh weight when 25 mg L-1 IAA was applied to seeds for 24 hr. In contrast to the activity of IAA oxidase, the activity of polyphenoloxidase (PPO) as well as of peroxidase increased in both the conditions - when plants switched from pre-flowering stage to flowering stage and also when IAA was applied, the concentration and duration again show a cumulative effect.

Effect of low temperature on flowering response and biochemical changes during the process of floral induction in Cucumis sativus

Tewari G;Kaur S;Soni M K;Sharma Y K

005745 Tewari G;Kaur S;Soni M K;Sharma Y K (Botany Dep, Lucknow Univ, Lucknow-226 007, Email: tewarigopal@gmail.com) : Effect of low temperature on flowering response and biochemical changes during the process of floral induction in Cucumis sativus. Res Envir Life Sci 2009, 2(3), 181-4.

Seeds of cucumber (Cucumis sativus L.), variety Jyoti Green Long, were exposed to low temperature (4°C) for - 0 (as control), 24, 48 and 72 hr and then allowed to germinate and grow in normal conditions for two weeks inside the laboratory. After two weeks five seedlings from each petridish were transplanted in pots and their development patterns up to anthesis were observed using morphological and biochemical (metabolites and enzyme activity) parameters. It was observed that exposure of seeds to low temperature had a profound effect on the flowering response in cucumber. Except the pollen sterility and the total No. of female flowers formed, all the morphological parameters studied viz. days to anthesis of male and female flowers; number of node bearing 1st male or female flower, total male flowers formed and ratio of male flowers to female flowers were decreased as compared to control, when low temperature was given for 24 and 48 hr; but different effect was observed on exposing to low temperature for 72 hr. The sucrose and starch content was found to increase with an increase in the duration of low temperature exposure to seeds up to 48 hr, beyond which it decreased significantly at 72 hr exposure, both at pre-flowering and flowering stages while the total protein content showed a different trend though. The activity of sucrose synthase increased significantly with increase in duration of low temperature up to 48 hours beyond which it decreased when compared to control. Similarly the activity of sucrose synthase decreased from pre-flowering to flowering stage in plants raised from seeds that were exposed to low temperature for 24, 48 and 72 hr respectively. Activity of acid invertase showed a trend just opposite to that of sucrose synthase. IAA oxidase showed a definite reduction in the activity with the increased duration of low temperature exposure. While at pre-flowering stage it was highest in control, the activity decreased significantly in plants which were raised from the seeds subjected to low temperature for 24, 48 and 72 hr respectively. The polyphenol oxidase (PPO) activity also increased markedly when plants experienced transition from pre-flowering to flowering stage. A similar trend to that of PPO was observed in case of peroxidase activity.

Dwarf mutations in grass pea (Lathyrus sativus L.): origin, morphology, inheritance and linkage studies

Talukdar D

005744 Talukdar D (Botany Dep, Kalyani Univ, Kalyani-741 235, Email: dib_tal@rediffmail.com) : Dwarf mutations in grass pea (Lathyrus sativus L.): origin, morphology, inheritance and linkage studies. J Genet 2009, 88(2), 165-75.

Induction of mutation has been used to create additional genetic variability in grass pea (Lathyrus sativus L.). During the ongoing investigations on different induced-morphological mutants, the author detected three types of dwarf mutants in grass pea. One mutant, designated as dwf1 type was earlier identified in colchicine-induced C₂ generation of grass pea variety BioR-231 while the other two, designated as dwf2 and dwf3 were isolated in 250 Gy and 300 Gy gamma ray irradiated M₂ progeny of variety 'BioR-231' and 'Hooghly Local', respectively. As compared to their parental varieties (controls), all the three mutants manifested stunted, erect and determinate stem, early maturity and tolerance to pod shattering habit. The mutants differed from each other, as well as with controls, in number of primary branches, nature of stipules and internodes, length of peduncle, leaflet and seed coat colour, seed yield and seed neurotoxin content. The three dwarf mutants were monogenically recessive and bred true in successive generations. F₂ segregation pattern obtained from the crosses involving the three mutants indicated that dwarf mutation in grass pea was controlled by two independent non-allelic genes, assigned as df1 (for dwf1 type), df2 (for dwf2 type) and df3 (for dwf3 type), with the df1 locus being multiple allelic. Primary trisomic analyses revealed the presence of df1/df2 locus on the extra chromosome of trisomic type I, whereas df3 was located on the extra chromosome of type III. Linkage studies involving five other phenotypic markers suggested linked association of df1df2 locus with Ifc (leaflet colour) and wgn (winged internode) and df3 locus with cbl (seed coat colour). Both the loci; however, assorted independently with flower colour and stipule character. The dwarf types can be utilized as valuable tools for further cytogenetic research and breeding of grass pea.

3 illus, 5 tables, 40 ref

Effect of plant growth hormones on the abscission of debladed petioles in Hibiscus sabdariffa L.

Srivastava S K;Srivastava P