## 4 What Are Hyphenated Techniques?
In 2012, the cassava (_Manihot esculent_ Crantz) genome was sequenced, assembled and annotated into scaffolds [147]. The genome was further improved and re-annotated into 40,044 contigs, 18 chromosomes and 30,033 loci [148]. The sequencing and assembly of the cassava genome is invaluable in the application of molecular technologies towards cassava improvement, and this includes the use of techniques such as transcriptome, metabolome and SNP profiling, metagenomics and proteomics studies in response to herbivous pests and pathogens. The genome information serves as a useful reference point for metabolome studies using hyphenated techniques because metabolites occupy the end of the spectrum of the central dogma of molecular biology. The literature provides several examples of studies that investigate cassava-insect/pathogen interactions using hyphenated techniques. For example, natural variation in resistance of cassava to whitelfy _Aleurotrachelus socialis_ was characterised using complementary metabolite profiling approaches [11]. A range of secondary metabolites dominated by the presence of phenylpropanoids and flavonoids were characterised using LC-MS, whilst the analysis of polar extracts facilitated the annotation of compounds and components of the intermediary and primary metabolism using GC-MS. In addition, secondary metabolites were identified and quantified in different parts of cassava plants infested and non-infested by mealybug _Phenacoccus mulinoti_ using HPLC technology [9]. Extracts from the apical and basal leaves of the different cassava cultivars contained caffeic acid, p-couramic acid, ferulic acid, rutin and trace amounts of gallic acid. Caffeic acid was mainly detected in the basal leaf extracts for all evaluated cultivars. Furthermore, rutin concentrations were higher in apical leaves than in basal leaves for all cultivars, regardless of whether the plants were infested by _P. maninhoti_. Given the successes of hyphenated techniques in delineating other biochemical processes of cassava which has been demonstrated by these studies, studies of hormonal responses of cassava to stress should surely yield results. Other studies have also been reported, including capturing biochemical diversity in cassava through the application of metabolite profiling [8]; metabolic profiles of six African cultivars of cassava (_Manihot esculent_ Crantz) to highlight bottlenecks of root yield [149]; photosynthesis, metabolites and soluble carbohydrates in cassava, focusing on potassium and storage root development [150]; elucidation of starch and carotenoid composition of thirteen Nigerian cassava landraces using gene expression and metabolite profiling techniques [151]. These studies support the existing reports that cassava responses to biotic and other stresses in general trigger a common cohort of responsive metabolites, providing insight into the general activation of metabolic pathways in response to stress. However, studies on the cassava hormonal defence machinery need broadening and intensification to reveal all underlying mechanisms. Other response mechanisms, besides hormonal responses, need to be studied for an in-depth understanding of the responses of cassava to biotic stresses.