In carnivorous plants J.D Hooker suggested that the digestion of carnivorous plants is like that of animals
which digestion J.D Hooker said?
Answers
Explanation:
Background
Carnivorous plants have been fascinating researchers with their unique characters and bioinspired applications. These include medicinal trait of some carnivorous plants with potentials for pharmaceutical industry.
Methods
This review will cover recent progress based on current studies on digestive enzymes secreted by different genera of carnivorous plants: Drosera (sundews), Dionaea (Venus flytrap), Nepenthes (tropical pitcher plants), Sarracenia (North American pitcher plants), Cephalotus (Australian pitcher plants), Genlisea (corkscrew plants), and Utricularia (bladderworts).
Results
Since the discovery of secreted protease nepenthesin in Nepenthes pitcher, digestive enzymes from carnivorous plants have been the focus of many studies. Recent genomics approaches have accelerated digestive enzyme discovery. Furthermore, the advancement in recombinant technology and protein purification helped in the identification and characterisation of enzymes in carnivorous plants.
Discussion
These different aspects will be described and discussed in this review with focus on the role of secreted plant proteases and their potential industrial applications.
Keywords: Carnivorous plants, Enzyme discovery, Digestive enzyme, Secreted protease, Industrial applications, Protein characterisation
Introduction
Nitrogen is the most crucial mineral nutrient required by plants but its availability is largely limited in many terrestrial ecosystems (Behie & Bidochka, 2013). For adaptation to such unfavourable environment, carnivorous plants have developed the ability to attract, capture, and digest preys into simpler mineral compounds, which are then absorbed for plant growth and reproduction (Ellison, 2006). The first evidence on the ability of the plant to capture and digest insects was provided over 140 years ago (Darwin, 1875). Since then, more than 700 carnivorous species from 20 genera of 12 families (Givnish, 2015) have been identified with captivating morphological and physiological traits linked to carnivory (Król et al., 2011).
There are a few reviews on the evolution of carnivorous plants and their biotechnological applications (Król et al., 2011; Miguel, Hehn & Bourgaud, 2018). However, a systematic review with focus on digestive enzyme discovery and characterisation from all families of carnivorous plants is lacking. Furthermore, the pharmacological potentials of some of these carnivorous plants have also been largely overlooked. With the advent of omics technology which accelerated enzyme discovery in carnivorous plants for the past few years, there is a pressing need for a timely review on current progress of studies in this field. This review will be useful not only to researchers working on carnivorous plants, but also those with interest in commercially useful enzymes and natural products.
Survey Methodology
In this review, we provide perspectives on the latest research of different carnivorous plants, namely Cephalotus, Drosera, Dionaea, Genlisea, Nepenthes, Sarracenia, and Utricularia, on their digestive enzyme discovery and characterisation. In earlier studies, research interest on carnivorous plants was centred on axenic culture, ultrastructure of specialised trapping organs, foliar absorption of nutrients derived from preys, and the enzymatic studies of prey digestion (Adamec, 1997; Gorb et al., 2004; Farnsworth & Ellison, 2008). Thus, this review summarises the previous findings with focus on digestive enzymes discovered in carnivorous plants, especially proteases and their industrial applications. The literature survey was performed exhaustively online using Google search engine and SCOPUS. The discussion will be mainly based on recent studies.
Different families of carnivorous plants
The emergence of carnivorous syndrome requires significant functional adaption in plant morphology and physiology. Carnivory trait has evolved independently in different orders of flowering plants, namely Caryophyllales, Ericales, Lamiales, Oxalidales, and Poales (Müller et al., 2004; Ellison & Gotelli, 2009; Król et al., 2011). This comprised of 12 different families of carnivorous plants with five distinct trapping mechanisms, including flypaper trap, snap trap, pitfall trap, suction trap, and eel trap (Table 1). The development of unique traps is one of the major indicators of carnivorous syndrome. These traps originate from the leaves specialised in trapping, digesting and absorbing nutrients from prey at the cost of reduced photosynthesis (Ellison & Gotelli, 2009). The modified leaves of carnivorous plants often form either an active or passive trap (Bauer et al., 2015). An active trap involves movement mechanics to aid prey capture, whereas a passive trap relies on its morphological structure to trap prey.