One of the most significant manifestations of environmental stress in plants is the increased production of Reactive Oxygen Species (ROS). These ROS, if allowed to accumulate unchecked, can lead to cellular toxicity. A battery of antioxidant molecules is present in plants for keeping ROS levels under check and to maintain the cellular homeostasis under stress. Ascorbate peroxidase (APX) is a key antioxidant enzyme of such scavenging systems. It catalyses the conversion of H2O2 into H2O, employing ascorbate as an electron donor. The expression of APX is differentially regulated in response to environmental stresses and during normal plant growth and development as well. Different isoforms of APX show differential response to environmental stresses, depending upon their sub-cellular localization and the presence of specific regulatory elements in the upstream regions of the respective genes. The present review delineates role of APX isoforms with respect to different types of abiotic stresses and its importance as a key antioxidant enzyme in maintaining cellular homeostasis.

Background Rice and maize go to family Poaceae contains many crops of agronomic trait and also represent two carbon metabolism systems, C3 and C4. Analysis of the maize sequence provides new insights into the employment of C3 genes to the C4 mechanism which allowed us to identify more orthologs in other crops. This investigation reports comparative account of genome wide in silico identification of C4 pathway related genes from Zea maize (Zm) and Oryza sativa (Os) from the available whole genome sequence information. The annotation of gene sequences, signature motif analysis, protein phophorylation analysis, study of upstream cis-acting elements, phylogenetic tree construction, chromosomal locations, syntenic mapping and microarray expression analysis of C4 pathway related gene family from both the genomes have been attempted. Results A total of 30 and 37 C4-pathway genes have been predicted from rice and maize genome respectively. Multiple-sequence-alignment and signature motif analysis of these proteins of rice and maize revealed high conserveness. Phophorylation analysis revealed that maize have high number than rice. The phylogenetic analysis of C4 related genes across both plant species clearly resulted in four sub-groups in both plants. In Rice, the 30 genes of C4 pathway related genes family are distributed on eleven out of twelve chromosomes, while in maize, they are randomly distributed on all the chromosomes. Most of the genes of Zm’s chromosome 1 show syntenic relationship with chromosome 1. The cis-regulatory-elements of Zm and Os genes suggested its diverse functions associated with plant growth development, stress and hormone responsiveness as well as endosperm and meristem specific gene expression. This investigation of Zm and Os can now offer new insights into the role of different C4 pathway related genes and examine the comparative syntenic mapping between two monocot models and allows for better understanding about how genes evolve within monocots. Therefore, in silico investigation of C4-photosynthetic-pathway gene family needs to be supported by wet lab experimentation of the novel genes for elucidating their function in many biological courses.Conclusion Results revealed that photosynthetic pathway related gene play a potent role in stress response and plant growth and development.