Overexpression of leucoanthocyanidin reductase or anthocyanidin reductase elevates tannins content and confers cassava resistance to two-spotted spider mite

Abstract

The two-spotted spider mite (TSSM) is a destructive cassava pest. Intensive demonstration of resistance mechanism greatly facilitates the creation of TSSM-resistant cassava germplasm. Gene to metabolite network plays a crucial role in modulating plant resistance, but little is known about the genes and related metabolites which are responsible for cassava resistance to TSSM. Here, a highly resistant (HR) and a highly susceptible (HS) cassava cultivar were used, integrative and comparative transcriptomic and metabolomic analyses between these two cultivars after TSSM infestation revealed that several genes and metabolites were closely related and significantly different in abundance. In particular, the expression of leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) genes showed a high positive correlation with most of the metabolites in the tannin biosynthesis pathway. Furthermore, transgenic cassava lines overexpressing either of the genes elevated tannin concentrations and conferred cassava resistance to TSSM. Additionally, different forms of tannins possessed distinct bioactivity on TSSM, of which total condensed tannins (LC50 = 375.68 mg/l) showed maximum lethal effects followed by procyanidin B1 (LC50 = 3537.10 mg/l). This study accurately targets LAR, ANR and specific tannin compounds as critical genes and metabolites in shaping cassava resistance to TSSM, which could be considered as biomarkers for evaluation and creation of pest-resistant cassava germplasm.

Trichomes and unique gene expression confer insect herbivory resistance in Vitis labrusca grapevines

“…Additionally, DEGs with constitutively increased expression in ‘GREM4’ compared to ‘PN40024’ were enriched in genes involved in the ‘biosynthesis of secondary metabolites’ pathway and the implicated 149 genes were mainly associated with terpene, carotenoid, phenylalanine-tyrosine-tryptophan, flavone-flavanol, stilbenoid, and flavonoid biosynthesis. Considering the role of terpenes, flavonoids, and other secondary metabolites in insect herbivory defense [ 47 – 49 , 51 , 54 , 61 , 113 , 114 ], it seems likely that increased basal expression of these genes translates to increases in such metabolites, conferring heightened constitutive defense against insect herbivory, though metabolomic tests are required to verify this hypothesis.…”

“…Additionally, other secondary metabolites, such as flavonoids, play important roles in insect herbivory defense and resistance such as observed in wheat, rice, tea, sorghum, and maize [ 49 – 53 ]. For example, in resistant cassava ( Manihot esculenta ), increased accumulations of phenylpropanoid and flavonoid pathway compounds were identified upon two-spotted spider mite ( Tetranychus urticae ) herbivory and led to greater resistance when genes associated with their biosynthesis were overexpressed [ 54 ]. While terpenes, flavonoids, and other secondary metabolites are critical to insect herbivory defense, physical adaptations, such as trichomes, hair-like structures on the surface of plant tissues, also provide increased defense against pathogens and insect pests [ 36 , 55 – 57 ].…”

Transcriptome sequencing of Cocos nucifera leaves in response to Rhynchophorus ferrugineus infestation

“…Nevertheless, anthocyanins play multiple roles in plants and their reduced biosynthesis may disturb the balance between photosynthesis and defense against RPW attack in coconut similar to Pseudowintera colorata ( Menzies et al, 2016 ). For instance, overexpression of LAR or ANR resulted in elevation of tannins content and confers cassava resistance to two-spotted spider mite ( Chen et al, 2022 ). Taken together, RPW attack induces expression changes in phenylpropanoid, flavonoid, and anthocyanin biosynthesis genes.…”

A Transformation and Genome Editing System for Cassava Cultivar SC8

“…Agrobacterium -mediated gene transformation or editing in the model cultivar ( M . esculenta cv TMS60444) has been used to modify cassava properties such as enhanced starch accumulation and modified starch functional properties [ 4 , 5 , 6 , 7 ], insect and disease resistances [ 8 , 9 ], abiotic stress tolerance [ 10 , 11 ], increased nutrients [ 12 , 13 ], and delayed post-harvest physiological deterioration (PPD) [ 14 , 15 ]. However, all these studies were performed on model cassava cv TMS60444, which is amenable to gene transformation.…”