Effects of δ‐aminolevulinic acid dehydratase silencing on the primary and secondary metabolisms of citrus

Abstract

δ‐aminolevulinic acid dehydratase (ALAD) is an important enzyme in tetrapyrrole synthesis. ALAD combines two δ‐aminolevulinic acid (δ‐ALA) molecules to form the pyrrole molecule, porphobilinogen, an important precursor for plant pigments involved in photosynthesis, respiration, and nutrient uptake. In this study, we investigated the effects of silencing of ALAD gene on citrus leaf pigments and metabolites. The ALAD enzyme was inhibited using virus‐induced gene silencing (VIGS) technology using citrus tristeza virus (CTV). δ‐ALA accumulated in citrus plants inoculated with the recombinant virus (CTV‐tALAD) to silence ALAD and resulted in discrete yellow spots (yellow islands) and necrosis in leaves and stems. The levels of chlorophylls, starch, sucrose, trans‐ and cis‐violaxanthin, and α‐ and β‐cryptoxanthin were reduced in CTV‐tALAD plants, whereas zeaxanthin was increased. The increase in zeaxanthin and the decrease in its precursors indicated that the reduction in chlorophylls resulted in light damage. Salicylic acid and jasmonic acid levels, as well as emission of (E)‐α‐bergamotene and (E)‐β‐farnesene, increased in CTV‐tALAD plants indicating these plants were under stress. Our results showed that silencing of ALAD induces stress in plants and that VIGS using mild CTV strains is a promising technique to study biological function of citrus genes.

Investigation of Heat-Induced Changes in the Grain Yield and Grains Metabolites, with Molecular Insights on the Candidate Genes in Barley

“…Its ortholog in Arabidopsis, AT1G44318, was found to be involved in chlorophyll biosynthesis. The silencing of this gene in citrus leaves resulted in a reduction in chlorophyll levels, starch, and sucrose [64]. These results indicate that this gene is crucial for chlorophyll biosynthesis, and subsequently, starch and sucrose biosynthesis, which could explain our results that CCF is positively and significantly correlated with starch content (Figure 4a).…”

Optimization of a virus-induced gene silencing system and functional elucidation of MaBAM9b in postharvest banana fruits

“…Finally, the gene function can be assessed based on the plant phenotype and physiological index alteration [9]. VIGS can be developed rapidly and has been applied to functional gene identi cation in eshy fruits, such as tomato [8,10], strawberry [11][12][13], apple [14][15], grape [16], citrus [17], loquat [18], pear [19][20], peach [21][22] , and sweet cherry [23][24]. However, there are no reports on VIGS in banana.…”

Silencing of δ‐aminolevulinic acid dehydratase via virus induced gene silencing promotes callose deposition in plant phloem

“…AY170468). 9 The plasmid, CTV-t ALAD -as was propagated in Nicotiana benthamiana and the purified virions were infiltrated in Citrus macrophylla . The empty plasmid, CTV-wt was inoculated in C. macrophylla to be used as a control in our study.…”

“…In addition, polar metabolites including L-alanine, gamma-aminobutyric acid, L-threonine, L-glutamic, and L-phenylalanine also were significantly decreased in leaves while L-asparagine, fumaric acid, and succinic acid significantly increased in leaves of ALAD -silenced plants. 9 Furthermore, expression profiles of 63 conserved microRNAs (miRNA) implicated in auxin biosynthesis and signaling, axillary shoot meristem formation and leaf morphology, starch metabolism, and oxidative stress were differentially expressed in ALAD -silenced citrus plants. 10 Levels of total phenolics, H 2 O 2 and superoxide anion (O 2 ‧ − ) were increased, further supporting the hypothesis that ALAD silencing-induced stress on citrus plants.…”