## 4 The Use of Nanotechnology for the Improvement of Endophytic Biocontrol Agents
These authors demonstrated the effectiveness in utilizing a multionics approach to identify crucial players within fungi that confer these positive biocontrol attributes. Thus, it can be proposed that by incorporating the [PERSON] et al., 2022 [51] approach (to establish the crucial players) and CRISPR/Cas9 systems to manipulate or alter these crucial players, these coupling techniques could potentially enhance/introduce similar attributes in other endophytes, to confer disease resistance and improve biocontrol activity in commodity crops. Screening Techniques for Identifying Secondary Metabolites Associated with Endophytic Microbes and Biocontrol Activity  
Many strategies have been developed to discover structurally novel natural products such as secondary metabolites from endophytic microorganisms, which could aid in various metabolic reactions within plants. Endophytic microorganisms store numerous novel secondary metabolites that can serve as an excellent source of plant-defense compounds against phytopathogens [52]. Due to the high number of commodity crops being affected by various soil-borne pathogens it necessitates the identification of novel compounds for crop improvement against phytopathogens. The use of chromatographic techniques in endophytic research has been explored and continues to grow due to the ongoing search for novel compounds [53]. There are four main different chromatographic techniques that have been used to study the compounds from endophytic microorganisms, which include gas chromatography, liquid chromatography, thin-layer chromatography and paper chromatography. The gas chromatography-mass spectrometry (GC-MS) technique has been used as one of the technology platforms for fingerprint analysis of secondary metabolites in both plant and non-plant species [54]. To understand the therapeutic effect of endophytic microorganisms in the plant, GC-MS has been used to identify the secondary metabolites that are responsible for the antimicrobial/antifungal activity against phytopathogens. In a study by [PERSON] et al., 2020 [55], GC-MS was used to identify volatile organic compounds that were isolated from four different Trichoderma strains _Trichoderma erinaceum_(IT-58), _Trichoderma gamsii_ (IT-62), _Trichoderma afroharzianum_ (P8) and _Trichoderma harzianum_ (P11). The study identified over 20 compounds in each extract, which included harzianolide, 68-hydroxyfluoxygenase, and 2,6-Bis (1,1-dimethylethyl)-4-(1-oxopropyl) phenol which the authors proposed contributed to the inhibition of the fungal growth of _Pythium myriotylum_. This study shows the successful use of GC-MS to identify secondary metabolites, which play a pivotal role in plant pathogen defense. High-pressure liquid chromatography (HPLC) is a chromatographic technique that is widely used in research for identifying bioactive compounds from endophytic microorganisms especially endophytic fungi. The advantages of using HPLC is that the analysis of the sample moves at high speed, it has a high sensitivity, and the quantification of results is accurate and precise [56]. A study by [PERSON] et al., 2020 [57] reported the identification of 2,6-pyridinedicarboxylic acid from _Simplicillium_ Chinense strain SneF5 using a HPLC. The identified compound exhibited a broad spectrum of activities, including antitumor, anti-inflammatory and antibacterial activities. The same study also showed the effectiveness of 2,6-pyridinedicarboxylic acid as an antagonist of the root rot nematode _Meloidoygne incognita_. This study highlights the increasing need for screening tools such as HPLC to be used to screen for potential biocontrol microorganisms, as well identifying compoundswithin microorganisms that can play an important role in controlling phytopathogens and improving plant health.