**3. Future prospects**

light energy from PSI to PSII by increasing LHCII content, which in turn accelerate the transformation from light energy to electronic energy, water photolysis and oxygen evolution.

Nadtochenko et al. [62] observed an enhanced electron transfer efficiency in isolated photosynthetic reaction centres using alumina nanoparticles. The bread wheat (*Triticum aestivum* L.) showed an increase in grain number, biomass, stomatal density, xylem-phloem

ticles have been reported to protect chloroplasts from aging during long illumination regimes, promote chlorophyll formation and stimulate Rubisco activity, which in turn results in increased photosynthesis or enhanced photosynthetic carbon assimilation [71, 77, 78]. With

water conductance and transpiration rate. Nano-anatase was reported to promote electron

ylation of chlorophyll under both visible and ultraviolet light [80]. A higher photosynthetic carbon reaction due to Rubisco carboxylation was observed as a result of nano-anataseinduced marker genes for Rubisco activase mRNA, enhanced protein levels and activities of

in a reduced PSII quantum yield, photochemical quenching, electron transfer rate, chlorophyll fluorescence and higher non-photochemical quenching and water loss [82]. Nano-TiO<sup>2</sup> reported to improve water absorption, seed germination, plant growth, nitrogen metabolism

gen evolution. The noncyclic photophosphorylation activity was found to be higher than cyclic photophosphorylation in chloroplasts. This increase in photosynthesis with nano-

light absorbance, conversion of light energy to electron energy and ultimately to chemical

In the recent time, NMs are used as a vital tool for improving plant growth and productivity under adverse environmental conditions, that is, salt stress. The Si nanoparticles in the soil have been shown to alleviate salt stress, enhance seed germination, improve activities of antioxidative enzymes, photosynthetic rate and leaf water content [89, 90]. Increased leaf, pod dry weight and grain yield were recorded in soya bean using nano-iron oxide [91]. The β-cyclo dextrin-coated iron nanoparticles penetrate the biological membranes of maize and increase the chlorophyll pigments (up to 38%) as compared to control [92]. The spray of citrate-coated

 improved Rubisco-carboxylase activity 2.67 times in spinach as compared to control, which consecutively activates Rubisco carboxylation and eventually the rate of photosynthesis increase [87]. Pradhan et al. [88] found that Mn-NPs induced an increase in the hill

 might be associated with the activation of a photochemical reaction in spinach chloroplasts [85, 86]. Similarly, an increase in dry weight, chlorophyll formation, the ribulose bisphosphate carboxylase/oxygenase activity and the photosynthetic rate was reported

(rutile) influences the photochemical reaction in spinach chloroplasts [85, 86].

, Qi et al. [79] observed an improved net photosynthetic rate,

NPs were reported to alleviate heat stress through

showed improved up-hill reaction and oxy-

) assimilation. Treatment of nano-anatase

rutile [83]. The nano-anatase TiO<sup>2</sup>

nanopar-

and photophosphor-


improved

size, epidermal cells and water uptake after seed priming with MWCNT [76]. TiO<sup>2</sup>

102 Photosynthesis - From Its Evolution to Future Improvements in Photosynthetic Efficiency Using Nanomaterials

transport chain reaction, photoreduction activity of PSII, evolution of O<sup>2</sup>

Rubisco activase [81]. On the contrary, the exogenous application of TiO<sup>2</sup>

exogenous application of TiO<sup>2</sup>

and photosynthesis [63, 76, 83, 84]. TiO<sup>2</sup>

The spinach treated with 0.25% nano-TiO<sup>2</sup>

in aged spinach treated with 2.5% nano-TiO<sup>2</sup>

reaction rate in mung bean (*Vigna radiata*).

energy, and this promotes carbon dioxide (CO<sup>2</sup>

regulating stomatal opening [79].

Nano-TiO<sup>2</sup>

TiO<sup>2</sup>

TiO<sup>2</sup>

Nanotechnology has enormous potential to create novel and improved functional properties in photosynthetic organelles and organisms for the enhancement of solar energy harnessing. The upward translocation from root to leaf opens up greater opportunities for their use in various delivery applications. The SWNTs delivered by this spontaneous mechanism have the potential for increasing chloroplast carbon capture by promoting chloroplast solar energy harnessing and electron transport rates. It has been shown that when nanoparticles enter into plant cell, various metabolic changes occur that leads to an increase in biomass, fruit/grain yield, and so on; therefore, further mode and action can be elucidated to evaluate the possibility of their uses. The nanomaterials have the potential to be utilized for the transport of DNA and chemicals into plant cells [95, 96] which offers new opportunity to target specific gene manipulation and expression in the specific cells of the plant. With nanomaterial, the output of a crop can be increased while reducing the input through a better understanding of nanoparticle interaction with plants. The nanobionics approach to engineer plant function will lead to a new area of research at the interface of nanotechnology and plant biology.
