Identification and expression analysis of S-alk(en)yl-L-cysteine sulfoxide lyase isoform genes and determination of allicin contents in Allium species

Abstract

Alliinase is the key enzyme in allicin biosynthesis pathway. In the current study, the identification and sequencing of alliinase genes along with determination of allicin contents were reported for Allium species with a novel report for Iranian endemic species. The presence of different isoforms in the Allium being discovered for the first time. In bulbs tissue, the highest allicin concentration was in Allium sativum, A. umbilicatum, and A. fistolosum (1.185%, 0.367%, and 0.34%, respectively), followed by A. spititatum (0.072%), A. lenkoranicum (0.055%), A. atroviolaseum (0.36%), A. rubellum (0.041%), and A. stamineum (0.007%). The highest allicin content in the leaves and roots were in A. sativum (0.13%), and A. stamineum (0.195%), respectively. The ORFs length ranged from 1416 in A. sativum (iso-allii-nase2; ISA2) to 1523 bp in A. sativum (alliinase); the identity with A. sativum (alliinase) varies from 95% to 68% for A. ampeloprasum, and A. sativum (iso-alliinase1, ISA1) respectively. These data suggested that both ISA1 and ISA2 had a high expression in the roots and bulbs compared to A. sativum as the control in all species. Note that ISA1 and ISA2 were not expressed in the leaves. The results showed that isoforms expression patterns among different tissues in Allium species were variable. The presence of various isoforms is a possible explanation for the difference between the species in terms of obtained results, especially the amount of allicin.

Transcriptome and phytochemical analyses provide insights into the organic sulfur pathway in Allium hirtifolium

“…Among Allium species, organic sulfur synthesis has a similar pathway, but secondary metabolite biosynthesis and accumulation are related to regulator genes with tissue-specific expression patterns, which highly affect the quantities and chemical compositions in each Allium species 21 . Given this, RNA-seq has been applied effectively to discover genes related to sulfur metabolism in some Allium species such as A. cepa 14 , 22 , 23 , A. sativum 12 , 24 , and Allium fistulosum 25 . So, the transcriptome analysis in another species allows us to provide a more in-depth exploration of various aspects of the sulfur pathway.…”

“…Functional transcriptome analysis revealed 11 alliinase transcripts belonging to four distinct genes expressed in all three tissues with a different pattern. It has been previously detected and demonstrated 14 that the isoforms expression pattern of alliinase gene is variable among different tissues of various Allium species. Previous studies 14 , 44 have also described the presence of nonhomologous alliinase genes in different tissues of A llium species, which is consistent with the results obtained in this study.…”

“…Alliinase genes have been identified and sequenced in several Allium species. Previous results indicate variation in alliinase isoforms expression patterns among different tissues in different Allium species 14 . These data suggest the presence of two different isoforms, ISA1 and ISA2, which usually show high expression in the roots and bulbs without any expression in the leaves.…”

Plant Secondary Metabolites: The Weapons for Biotic Stress Management

“…Garlic ( Allium sativum ), leeks ( Allium porrum ), and onion ( Allium cepa ) are examples of the alliin–alliinase pathway [ 21 ]. These two pathways are evolved in herbivore defense and avoid pathogenic attack [ 28 ]. Table 2 represents examples of various sulfur-containing secondary metabolites.…”

Novel NARC-G1 garlic: comparative allicin quantification with morpho-biochemical & genetic profiling

“…Since the enzymatic reaction of the alliinase produces the bioactive compound in garlic, the studies analyzed the genetic profile of the gene. These studies revealed the existence of multiple variations i.e., insertion/ deletion in the exonic and intronic regions which play the significant role in differential expression of the alliinase gene hence responsible for the allicin content in individual garlic genotypes (Ovesná et al, 2015;Sayadi et al, 2020).…”