Induction of flowering in Lemna paucicostata, a short-day plant, by chelating agents and iron

Lemna paucicostata is a short-day plant which normally flowers only in a medium supplemented with EDTA or EDDHA. On a molar basis EDDHA is more effective for induction of flowering. The chelating agent can be replaced by high concentrations of ferric citrate in the medium. Simultaneous supply of both EDDHA and a high level of ferric citrate results in flowering even under long days

Differentiation in explants from mature leguminous trees

Stem and petiole explants, obtained from mature trees, of Albizzia lebbeck, Cassia fistula and C.siamea callused and differentiated shoot-buds and later shoots on B5 medium supplemented with either 0.5 mg/l IAA + 1 mg/l BAP or BM + 2 mg/l NAA + 0.5 mg/l BAP. The stem explants were more responsive than the petiole explants. In A.lebbeck, the IAA substituted medium favoured differentiation from both types of explants. However, in C.fistula, the type of explants rather than the medium composition had an overriding influence on shoot differentiation since those from petiole hardly responded in either medium. It has been possible to obtain plantlets from both A.lebbeck and C.fistula under conditions conducive to rooting. Plantlets of A.lebbeck have also been successfully transferred to the field

Developmental and light-dependent cues interact to establish steady-state levels of transcripts for photosynthesis-related genes (psbA, pbsD, psaA and rbcL) in rice (Oryza sativa L.)

The steady-state transcript levels for psbA, psbD, psaA and rbcL are low in dark-grown rice seedlings as compared to those grown in light. Following seed germination, they accumulate in an age-dependent manner, in dark as well as light, reaching a maximal level on the 7th or 8th day, before a slow decline sets in. But transcripts for psbA and psbD continue to maintain relatively-high levels even after 10 days of growth in light. Exposure of 5-day-old dark-grown seedlings to light results in an approximately 25-60-fold increase in transcripts during a period of 72 h, followed by a decrease. An analysis of data from both lines of investigation reveals that the developmental programme increases the transcript levels for psbA, psbD, psaA and rbcL by about 10-, 2.3-, 7.0- and 8.0-fold, respectively, between 5-8 days after germination and it is independent of light. At the same time, exposure of the seedlings to light during this period further enhances transcript levels by 5-, 11.4-, 6.6- and 7.8-fold, respectively. Thus, both developmental and light-dependent cues contribute to establish steady-state levels of transcripts for the chloroplast genes investigated

Induction of flowering by cytokinins in a short-day plant, Lemna paucicostata

Lemna paucicostata, normally a short-day plant, can be induced to flower under long-day conditions by providing a cytokinin in a medium containing a high level of ferric citrate (5 × 10-4M). Interestingly, when a cytokinin and EDDHA are present together in the medium, flowering is induced even at low levels of iron (10-5 and 5 × 10-5M ferric citrate). However, in the absence of a cytokinin, flowering takes place only under short days

Growth and flowering of Lemna paucicostata I. General aspects and role of chelating agents in flowering

Lemna paucicostata HEGELM. is normally a short-day plant and flowers only in the presence of a chelating agent (EDTA or EDDHA) in the medium. The plant can be induced to flower even by a single long night treatment; the flowering percentage, however, increases with further inductive cycles. The length of the critical dark period depends upon the chelating agent employed in the medium. It is between 10 and 12 hr in the medium containing EDTA and about 8 hr in the EDDHA-supplemented medium. Red light interruption in the middle of the dark period-even for a minute-is inhibitory for flowering. Attempts to identify the metal ion(s) chelated reveal that the chelating agents affect flowering by facilitating iron uptake. This is also supported by the fact that the requirement of a chelating agent for flowering can be overcome with an excess of iron in the medium. Interestingly, provision of EDDHA and excess of ferric citrate, together, can bring about flowering even under long days

Respiration in the developing ovules of poppy (Papaver somniferum L.)

This article does not have an abstract

Occurrence of gibberellin-like factors in watermelon

This article does not have an abstract

Changes in the carbohydrates, proteins and nucleic acids during seed development in opium poppy

This investigation is concerned with the major changes in the levels of carbohydrates, proteins, nucleic acids and some enzymes in the ovules of Papaver somniferum at various stages of seed development. Of the soluble sugars, fructose and glucose are present in large amounts up to the free nuclear stage of the endosperm but decrease rapidly when the latter turns cellular; then sucrose becomes most abundant. At this time the concentration of insoluble carbohydrates is almost one-seventh that of soluble and the activities of α- and β-amylases are at their highest. The nitrogen in the seed is accumulated in two phases, the first coinciding with the development of endosperm and the second with the development of embryo. Cell wall formation in the coenocytic endosperm is accompanied with a marked decrease in the soluble nitrogen. The activity of glutamic-alanine transaminase increases concurrently with the increase of protein in the ovules. The maximal RNA content is attained after the ovules have completed their increase in size but prior to the deposition of proteinaceous reserves in the endosperm. The amount of DNA increases with the growth of endosperm but decreases during the maturation of embryo. Both ribonuclease and deoxyribonuclease show two pH optima corresponding to pH 5.5 and 7.5 (ribonuclease) and 5.0 and 7.5 (deoxyribonuclease). Their activities seem to be correlated to the levels of nucleic acids