Accumulation of terpenoid phytoalexins in maize roots is associated with drought tolerance.
Maize (Zea mays) production, which is of global agro-economic importance, is largely limited by herbivore pests, pathogens and environmental conditions, such as drought. Zealexins and kauralexins belong to two recently identified families of acidic terpenoid phytoalexins in maize that mediate defence against both pathogen and insect attacks in aboveground tissues. However, little is known about their function in belowground organs and their potential to counter abiotic stress. In this study, we show that zealexins and kauralexins accumulate in roots in response to both biotic and abiotic stress including, Diabrotica balteata herbivory, Fusarium verticillioides infection, drought and high salinity. We find that the quantity of drought-induced phytoalexins is positively correlated with the root-to-shoot ratio of different maize varieties, and further demonstrate that mutant an2 plants deficient in kauralexin production are more sensitive to drought. The induction of phytoalexins in response to drought is root specific and does not influence phytoalexin levels aboveground; however, the accumulation of phytoalexins in one tissue may influence the induction capacity of other tissues.
Bacterial Foodborne Pathogens and Mycology, Agricultural Research Service, United States Department of Agriculture, Peoria, IL, 61604, USA.
Martha M
MM
Vaughan
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Shawn
S
Christensen
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Eric A
EA
Schmelz
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Alisa
A
Huffaker
Department of Entomology and Nematology, University of Florida, Gainesville, FL, 32611, USA.
Heather J
HJ
McAuslane
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Hans T
HT
Alborn
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Maritza
M
Romero
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Leon Hartwell
LH
Allen
Chemistry Research Unit, Center of Medical, Agricultural, and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL, 32608, USA.
Peter E A
PE
Teal
D000040:Abscisic Acid / Q000494:pharmacology; D000222:Adaptation, Physiological; D053898:Biosynthetic Pathways; D055864:Droughts; D060434:Herbivory; D010935:Plant Diseases / Q000382:microbiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics; D018517:Plant Roots / Q000187:drug effects / Q000382:microbiology / Q000502:physiology; D015398:Signal Transduction; D013312:Stress, Physiological; D013729:Terpenes / Q000737:chemistry / Q000378:metabolism*; D003313:Zea mays / Q000187:drug effects / Q000382:microbiology / Q000502:physiology*
D010937:Plant Growth Regulators; D010940:Plant Proteins; D013729:Terpenes; D000040:Abscisic Acid
ANTHER EAR2 (AN2); abiotic and biotic stress; root-to shoot ratio; salt stress