Structurally diverse specialized metabolites of maize and their extensive biological functions

Abstract

Maize originated in southern Mexico and various hybrid varieties have been bred during domestication. All maize tissues are rich in specialized plant metabolites (SPMs), which allow the plants to resist the stresses of herbivores and pathogens or environmental factors. To date, a total of 95 terpenoids, 91 phenolics, 31 alkaloids, and 6 other types of compounds have been identified from maize. Certain volatile sesquiterpenes released by maize plants attract the natural enemies of maize herbivores and provide an indirect defensive function. Kauralexins and dolabralexins are the most abundant diterpenoids in maize and are known to regulate and stabilize the maize rhizosphere microbial community. Benzoxazinoids and benzoxazolinones are the main alkaloids in maize and are found in maize plants at the highest concentrations at the seedling stage. These two kinds of alkaloids directly resist herbivory and pathogenic infection. Phenolics enhance the cross‐links between maize cell walls. Meanwhile, SPMs also regulate plant–plant relationships. In conclusion, SPMs in maize show a large diversity of chemical structures and broad‐spectrum biological activities. We use these to provide ideas and information to enable the improvement of maize resistances through breeding and to promote the rapid development of the maize industry.

Maize diterpenoid sensing via Ste3 a-pheromone receptor and rapid germination ofColletotrichum graminicolaoval conidia facilitating root infection

“…This colorless diterpenoid is secreted from maize roots and has antimicrobial functions 34 . Diterpenoids are described to take part in terpenoid-based defenses against various maize pathogenic species, including the fungi Rhizopus microsporus, Ustilago maydis, or F. graminearum but also herbivorous and insect species 44 . Similar to findings regarding class III peroxidases, the biosynthesis of several deterpenoids is inducible by plant pathogens as well as defense-related phytohormons jasmonic acid and ethylene [45][46][47][48] .…”

“…This colorless diterpenoid, secreted from maize roots, has antimicrobial properties (Mafu et al, 2018). Diterpenoids are involved in terpenoid-based defenses against various maize pathogens, including fungi such as Rhizopus microsporus, Ustilago maydis, and F. graminearum, as well as herbivorous and insect species (Zhou et al, 2023). Similar to class III peroxidases, the biosynthesis of several diterpenoids is induced by plant pathogens and defense-related phytohormones such as jasmonic acid and ethylene (Schmelz et al, 2011, Hiraga et al, 2001, Kidwai et al, 2020.…”

Chemical Structure Diversity and Extensive Biological Functions of Specialized Metabolites in Rice

“…Twenty-one monoterpenoids have been found in rice to date. These volatile monoterpenoids largely comprise chain monoterpenoids (1)(2)(3)(4) and cyclic monoterpenoids (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21), which are found mainly in rice leaves, bran, seeds, and bran oil [28][29][30][31][32][33][34][35][36]. These are the volatile components responsible for most of rice's aroma.…”

“…Specialized metabolites (SPMs) enable plants to defend themselves against biological and abiotic stresses from their environment [2][3][4]. Rice contains abundant SPMs, which are able to prevent herbivory, resist infection from pathogens and plant oxidation, and regulate plant growth and development, with some also having allelopathic effects [4][5][6][7][8].…”