Pleiotropic effects of recombinant protease inhibitors in plants

Abstract

Recombinant gene encoded protease inhibitors have been identified as some of the most effective antidigestive molecules to guard against proteolysis of essential proteins and plant attacking proteases from herbivorous pests and pathogenic microorganisms. Protease inhibitors (PIs) can be over expressed in transgenic plants to complement internal host defense systems, Bt toxins in genetically modified pest resistance and abiotic stress tolerance achieved through cystatins expression. Although the understanding of the role of proteolytic enzymes and their inhibitors encoded by both endogenous and transgenes expressed in crop plants has significantly advanced, their implication in biological systems still requires further elucidations. This paper, therefore, succinctly reviewed most recently published literature on recombinant proteases inhibitors (RPIs), focusing mainly on their unintended consequences in plants, other living organisms, and the environment. The review discusses major negative and unintended effects of RPIs involving the inhibitors’ non-specificity on protease enzymes, non-target organisms and ubiquitous versatility in their mechanism of inhibition. The paper also discusses some direct and indirect effects of RPIs such as degradation by distinct classes of proteases, reduced functionality due to plant exposure to severe environmental stress and any other potential negative influences exerted on both the host plant as well as the environment. These pleiotropic effects must be decisively monitored to eliminate and prevent any potential adverse effects that transgenic plants carrying recombinant inhibitor genes may have on non-target organisms and biodiversity.

Differential activity of wheat antioxidant defense system and alterations in the accumulation of osmolytes at different developmental stages as influenced by marigold (Tagetes erecta L.) leachates

“…Plant proteases play an important role in many different biological processes including stomatal development and distribution, as well as systemic stress response. They are also related to the increase in ROS production detected during plant exposure and response to environmental stress ( Mangena, 2022 ). Proteases mitigate this process by degradation of damaged, denatured proteins, remobilizing amino acids and generating molecules involved in signal transduction ( D’Ippólito et al., 2021 ).…”

In order to lower the antinutritional activity of serine protease inhibitors, we need to understand their role in seed development

“…Unfortunately, the exact biological function of SPIs has not yet been fully elucidated ( Grosse-Holz and van der Hoorn, 2016 ). This is despite the fact that SPIs are present in different organs and associated with different functions, such as defense against biotic and abiotic stresses ( Sun et al., 2015 ; Rodríguez-Sifuentes et al., 2020 ; Mangena, 2022 ). In this regard, any detailed work is still scarce on demonstrating a particular function of SPIs in viable seed production.…”