**5. Metabolic regulation of plant PCD**

Hormones play an important role in plant PCD. Ethylene, methyl jasmonate, and salicylate have been identified as key regulators which involved in the


#### **Table 2.**

*List of studies depicted the environmental stress stimulate PCD in plants.*

different developmental process like senescence [89]. The increased production of ethylene and salicylic acid associated with ROS-dependent PCD has been investigated [90]. In response to PCD, identified up-regulated genes and associated metabolism processes are autophagy transport, response to ROS, ABA signaling, metal-ion binding, DNA/Protein binding, carotene metabolism, glutamine synthase 2, caspase activity, pectinesterase activity, ethylene signaling, and lipid catabolism. Simultaneously down-regulated genes and associated metabolism processes amino acid metabolism, chlorophyll biosynthesis, carotenoid biosynthesis cytokinin-mediated signaling, glycine metabolism,


*Programmed Cell Death (PCD) in Plant: Molecular Mechanism, Regulation, and Cellular… DOI: http://dx.doi.org/10.5772/intechopen.97940*


#### **Table 3.**

*List of plant growth regulators (PGRs), other metabolites, and their role in plant PCD.*

photosynthesis, glutamine synthase 1 [91]. In response to PCD expression profile of ROS-scavenging enzymes such as peroxidase, ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX)) and non-enzymatic antioxidants ascorbic acid (AsA) and glutathione (GSH) also be studied in *Triticum aestivum* [12]. Yang *et al*, [92] investigated that Acyl-CoA Synthetase (ACOS) is one of the enzymes involved in fatty acids metabolic and protect tapetum cells from PCD and maintain reproductive fitness in rice. Some important findings refers that PGRs, different metabolites are played key role in PCD in plant (**Table 3**). Thus the complex metabolic network is involved in PCD in the plant system. The further systematic metabolic study will be required to understand and enrich our current understanding.

## **6. Conclusion**

In the present study, we have discussed the recent status of occurrence, cellular dysfunction and molecular mechanism of the most complicated fundamental processes of PCD in the plant. Due to the lack of sufficient study on PCD in plant systems, we are unable to identify and describe the exact molecular mechanism. The complex process of PCD is triggered in normal development as well as in response to stress. To understand (1) how plant cell sense or become competent towards PCD? (2) what are the specific signaling pathways correspond to different types of plant PCD?, integrated omic study is helpful in the near future. In our recent study, we have identified novel Cell division cycle and apoptosis regulator 1 (CCAR1) protein in plant system and computationally characterized their function in plant PCD [103]. Thus spectaculars study will be required for understanding the PCD in plant system.

*Regulation and Dysfunction of Apoptosis*
