No more recalcitrant: Chickpea regeneration and genetic transformation

Chickpea production is limited worldwide because of abiotic and biotic stresses. Efforts to overcome these production constraints through traditional breeding are difficult due to limited genetic variation. Novel regeneration is pre-requisite for genetic transformation offers the opportunity to overcome hybridization barriers and introduce novel genes for resistance. Although direct gene transfer via direct DNA transfer has been reported, Agrobacterium mediated transformation is the preferred method and standard protocols have been established for the production of transgenic plantlets derived from cocultivation of embryonic axes. This was soon adopted due to difficulties associated with regeneration of whole plants from callus. Only few reports have been reported using genetic transformation/transgene(s) against abiotic stress tolerance transgenic chickpea plants. Transgenic chickpea using bacterial codA gene tolerance against abiotic stresses have been developed. Chickpea improvement and application of genomics tools to the study of the chickpea genome will be enhanced through the use of genetic transformation

Roots of Pennisetum sp. possess the competence to generate nanoparticles of noble metals

461-467Roots of plants have immense reducing potential. Ions of noble metals namely Au3+ and Ag+ get reduced easily to form Au and Ag nanoparticles (NPs), respectively. Therefore, we hypothesize that plant roots could have potential to form Au-NPs and Ag-NPs. For present investigations, plants of Pennisetum glaucum L. were used to evaluate if their roots possess capacity to generate metal NPs. The generation of Au-NPs and Ag-NPs was initially presumed based on colour change, and confirmed by UV-vis spectra, TEM and EDX investigations. Pale yellow Au3+ and colourless Ag+ solutions turned purple and brown, respectively, by roots of Pennisetum sp. within 8 h. Absorption spectra of respective solutions showed plasmon resonance band at 560 nm and 420 nm confirming the presence of Au-NPs and Ag-NPs. TEM coupled with SAED revealed the presence of crystalline spherical NPs in the size range of 5-50 nm in these solutions. EDX further confirmed the presence of Au and Ag as NPs of respective solutions. These results confirmed that the roots of P. glaucum possess ideal reducing strength to generate Au-NPs and Ag-NPs exogenously in the aqueous phase

Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles

Characterization of high temperature induced stress impairments in thylakoids of rice seedlings

220-229Exposure o f isolated thylakoids or intact plants to elevated temperature is known to inhibit photosynthesis at multiple sites. We have investigated the effect of elevated temperature (40°C) for 24 hr in dark on rice seedlings to characterize the extent of damage by inl vivo heat stress on photofunctions of photosystem II (PSII). Chi a fluorescence transient analysis in the intactrice leaves indicated a loss in PSII photochemistry (Fv) and an associated loss in the number of functional PSII units. Thylakoids isolated from rice seedlings exposed to mild heat stress exhibited > 50% reduction in PSII catalyzed oxygen evolution activity compared to the corresponding control thylakoids. The ability of thy lakoid membranes from heat exposed seed lings to photooxidize artificial PSII electron donor, DPC, subsequent to washing the thylakoids with alkaline Tris or NH2OH was also reduced by ~40% compared to control Tris or NH2OH washed thylakoids. This clearly indicated that besides the disruption of oxygen evolving complex (OEC) by 40°C heat exposure for 24 hr, the PSII reaction centers were impaired by inl vivo heat stress. The analysis of Mn and manganese stabilizing protein (MSP) contents showed no breakdown of 33 kDa extrinsic MSP and only a marginal loss in Mn. Thus, we suggest that the extent of heat induced loss of OEC must be due to disorganization of the OEC complex by in vivo heat stress. Studies with inhibitors like DCMU and atrazine clearly indicated that in vivo heat stress altered the acceptor side significantly. [14C] Atrazine binding studies clearly demonstrated that there is a significant alteration in the QB binding site on D1 as well as altered QA to QB equilibrium. Thus, our results show that the loss in PSII photochemistry by in vivo heat exposure not only alters the donor side but significantly alters the acceptor side of PSII .</span

Potential of isolated thylakoids/chloroplasts of <i>Spinacia oleracea</i> to generate Au-nanoparticles in presence of light and dark when suspended in Au³⁺ solutions (0, 0.5, 1 and 2 mM).

<p>(A) Color of Au³⁺ solutions in dark (D) and light (L); (B) and (C) absorption spectra; (D) absorbance at 545 nm of Au³⁺ solutions incubated in dark and light, respectively. Values represent mean of data collected from six independent experiments. Values designated by different small letters are significantly different at P≤0.05 (Duncan's multiple range test).</p

Potential of isolated thylakoids/chloroplasts of <i>Spinacia oleracea</i> to generate Au-nanoparticles.

<p>(A) Impact of light of varying photon flux density on generation of Au-nanoparticles in 30 min by isolated thylakoids/chloroplasts sincubated in 2 mM Au³⁺; (B) Time dependent variation in generation of Au-nanoparticles by isolated thylakoids/chloroplasts incubated in 2 mM Au³⁺ exposed to light of varying photon flux density (µmol m⁻² s⁻¹). Values represent mean of data collected from six independent experiments. Values designated by different small letters are significantly different at P≤0.05 (Duncan's multiple range test).</p

Mechanism for generation of Au-nanoparticles by isolated chloroplasts in presence of light.

<p>Photosynthetic machinery driven by light energy splits water into protons, electrons and oxygen. While electrons are transported to NADP⁺, proton gradient is used for generation of ATP. Present investigations support that electrons can also be donated by light energy driven photosynthetic electron transport system to Au³⁺ to form Au⁰, which nucleate to generate Au nanoparticles.</p

Potential of isolated thylakoids/chloroplasts of <i>Potamogeton nodosus</i> to generate Au-nanoparticles in presence of light and dark when suspended in Au³⁺solutions (0, 0.5, 1 and 2 mM).

<p>(A) Color of Au³⁺ solutions in dark (D) and light (L); (B) and (C) absorption spectra; (D) absorbance at 545 nm of Au³⁺ solutions incubated in dark and light, respectively. Values represent mean of data collected from six independent experiments. Values designated by different small letters are significantly different at P≤0.05 (Duncan's multiple range test).</p

Characterization of Au-nanoparticles synthesized by isolated thylakoids/chloroplasts of <i>Spinacia oleracea</i> in presence of light.

<p>(A) TEM image; (B) SAED pattern; (C) EDX spectra; and (D) PXRD pattern of Au-nanoparticles.</p

Characterization of Au-nanoparticles synthesized by isolated thylakoids/chloroplasts of <i>Potamogeton nodosus</i> in presence of light.

<p>(A) TEM image; (B) SAED pattern; (C) EDX spectrum; and (D) PXRD pattern of Au-nanoparticles.</p