Contribution of Maize Polyamine and Amino Acid Metabolism Toward Resistance Against Aspergillus flavus Infection and Aflatoxin Production

Abstract

Polyamines (PAs) are ubiquitous polycations found in plants and other organisms that are essential for growth, development, and resistance against abiotic and biotic stresses. The role of PAs in plant disease resistance depends on the relative abundance of higher PAs [spermidine (Spd), spermine (Spm)] vs. the diamine putrescine (Put) and PA catabolism. With respect to the pathogen, PAs are required to achieve successful pathogenesis of the host. Maize is an important food and feed crop, which is highly susceptible to Aspergillus flavus infection. Upon infection, the fungus produces carcinogenic aflatoxins and numerous other toxic secondary metabolites that adversely affect human health and crop value worldwide. To evaluate the role of PAs in aflatoxin resistance in maize, in vitro kernel infection assays were performed using maize lines that are susceptible (SC212) or resistant (TZAR102, MI82) to aflatoxin production. Results indicated significant induction of both PA biosynthetic and catabolic genes upon A. flavus infection. As compared to the susceptible line, the resistant maize lines showed higher basal expression of PA metabolism genes in mock-inoculated kernels that increased upon fungal infection. In general, increased biosynthesis and conversion of Put to Spd and Spm along with their increased catabolism was evident in the resistant lines vs. the susceptible line SC212. There were higher concentrations of amino acids such as glutamate (Glu), glutamine (Gln) and γ-aminobutyric acid (GABA) in SC212. The resistant lines were significantly lower in fungal load and aflatoxin production as compared to the susceptible line. The data presented here demonstrate an important role of PA metabolism in the resistance of maize to A. flavus colonization and aflatoxin contamination. These results provide future direction for the manipulation of PA metabolism in susceptible maize genotypes to improve aflatoxin resistance and overall stress tolerance.

Transcriptome Analysis of Acid-Responsive Genes and Pathways Involved in Polyamine Regulation in Iron Walnut

“…Two nearly identical large sub-clusters and a small sub-cluster in cluster X all contained sequences related to photosynthesis and chlorophyll, indicating that differences in nucleotide sequences occurred within the high-expression genes in cluster X, although these nucleotide sequences have similar biological functions. A similar phenomenon was also found in Arabidopsis thaliana [42], Capsicum annuum [43], Lactobacillus kefiranofaciens [44], Rana arvalis [45], and Zea mays [46].…”

γ‐Aminobutyric acid and related amino acids in plant immune responses: Emerging mechanisms of action

“…Rice cell suspensions exposed to treatments with P. oryzae lysates showed increased GABA levels in a GAD‐independent manner (Forlani, Bertazzini, & Giberti, ), and grape ( Vitis vinifera L.) varieties with high catabolism of PA were shown to possess higher GABA levels and increased resistance towards B. cinerea (Hatmi et al, ). Likewise, the tolerance of maize ( Zea mays L.) towards Aspergillus flavus infection was correlated to higher catabolism of PAs when comparing resistant and susceptible maize lines in in vitro experiments (Majumdar et al, ). PA‐dependent GABA synthesis seems to be relevant also in the context of bacterial infections.…”

Hydroxycinnamic Acids and Their Derivatives in Broa, a Traditional Ethnic Maize Bread

“… # Peak number; (+) compounds detected in positive ion mode; (−) compounds detected in negative ion mode, Ұ compounds identified by commercial standards; RT: retention time (minutes); SF: soluble fraction; IF: insoluble fraction; B, M, R, W: compounds detected in bread, maize, rye, and wheat; n/d: not determined due to the peak’s low intensity and/or poor peak resolution. Bold: characteristic fragment ions described by other authors [ 7 , 9 , 10 , 12 , 13 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 ]; main MS/MS ions are ordered according to their decreasing intensities. …”

“…The role of HCAAs in maize grains is not known for sure [ 5 ]. They may be associated with several processes, such as plant growth and development, floral induction and reproduction, cell division, control of intracellular polyamine concentrations, cell wall reinforcement, and plant adaptation to stress, such as resistance to cold or pathogen attack [ 9 , 10 , 11 , 12 ]. To the best of our knowledge, HCAAs have not been detected in maize-based foods.…”