Phytonanotechnology: Recent applications and the role of Biocorona

Phytonanotechnology is lately gaining increased interest owing to its potential to modernize agriculture for better yield and nutritional quality. Consequently, Nano-Agri products like nano-biosensors, nano-carriers, and growth augmenters are being developed and applied. However, the limited knowledge of molecular interactions taking place at nano-bio interface remains a major concern. The nanotechnological interventions for healthier crops could rather turn out tobe risky and inefficient in the absence ofclear understanding of molecular mechanisms of nano-bio interactions. Upon entry into tissues or cells, nanoparticles (NPs) adsorb biomolecules forming a biocorona which determines NP uptake, translocation, and reactivity. The composition of biocorona is dependent on the physicochemical characteristics of the NPs, their surroundings, and the interaction time. Recent nascent studies in plants showed the potential of biocorona to influence major cellular pathways or plant responses like energy synthesis, pathogenesis, stress tolerance, and leaf senescence. This mini-review aims at summarizing the recent application of phytonanotechnology, the current status of biocorona studies with an overview of research bottlenecks and future prospects.

Antifreeze proteins enable plants to survive in freezing conditions.

Overwintering plants secrete antifreeze proteins (AFPs) to provide freezing tolerance. These proteins bind to and inhibit the growth of ice crystals that are formed in the apoplast during subzero temperatures. Antifreeze activity has been detected in more than 60 plants and AFPs have been purified from 15 of these, including gymnosperms, dicots and monocots. Biochemical characterization of plant antifreeze activity, as determined by the high ice recrystallization inhibition (IRI) activities and low thermal hysteresis (TH) of AFPs, showed that their main function is inhibition of ice crystal growth rather than the lowering of freezing temperatures. However, recent studies showed that antifreeze activity with higher TH also exists in plants. Calcium and hormones like ethylene and jasmonic acid have been shown to regulate plant antifreeze activity. Recent studies have shown that plant AFPs bind to both prism planes and basal planes of ice crystals by means of two flat ice binding sites. Plant AFPs have been postulated to evolve from the OsLRR-PSR gene nearly 36 million years ago. In this review, we present the current scenario of plant AFP research in order to understand the possible potential of plant AFPs in generation of freezing-tolerant crops.

Antisense expression of a gene encoding a calcium-binding protein in transgenic tobacco leads to altered morphology and enhanced chlorophyll.

Entamoeba histolytica contains a novel calcium-binding protein like calmodulin,which was discovered earlier,and we have reported the presence of its homologue(s)and a dependent protein kinase in plants.To understand the functions of these in plants,a cDNA encoding a calcium-binding protein isolated from Entamoeba histolytica (EhCaBP)was cloned into vector pBI121 in antisense orientation and transgenic tobacco plants were raised.These plants showed variation in several phenotypic characters,of which two distinct features,more greenness and leaf thickness,were inherited in subsequent generations.The increase in the level of total chlorophyll in different plants ranged from 60% to 70%.There was no major change in chloroplast structure and in the protein level of D1,D2,LHCP and RuBP carboxylase.These morphological changes were not seen in antisense calmodulin transgenic tobacco plants,nor was the calmodulin level altered in EhCaBP antisense plants.