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Trypsin and α ‐amylase inhibitors are differentially induced in leaves of amaranth ( Amaranthus hypochondriacus ) in response to biotic and abiotic stress
Author(s) -
SánchezHernández Carla,
MartínezGallardo Norma,
GuerreroRangel Armando,
ValdésRodríguez Silvia,
DélanoFrier John
Publication year - 2004
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.0031-9317.2004.00398.x
Subject(s) - amaranthus hypochondriacus , amaranth , amaranthaceae , trypsin , trypsin inhibitor , amylase , biology , methyl jasmonate , biochemistry , abiotic stress , botany , enzyme , gene
Seeds of Amaranthus hypochondriacus L. are known to accumulate a trypsin‐inhibitor (ATI) member of the potato‐I inhibitor family and an α ‐amylase inhibitor (AAI), possessing a knottin‐like fold. They are believed to have a defensive role due to their inhibition of trypsin‐like enzymes and α ‐amylases of insect pests. In this work, both inhibitory activities were found in leaves of young A. hypochondriacus plants. High constitutive levels of foliar inhibitory activity against bovine trypsin and insect α ‐amylases were detected in in vitro assays. Trypsin inhibitory activity was further increased by exposure to diverse treatments, particularly water stress. Salt stress, insect herbivory and treatment with exogenous methyl jasmonate (MeJA) or abscisic acid (ABA) also induced trypsin inhibitor activity accumulation, although to a lesser degree. In gel and immunoblot analyses showed that foliar trypsin inhibitor activity was constituted by at least three different inhibitors of approximately 29, 8 (including ATI) and 3 kDa, respectively. These inhibitors showed differing patterns of accumulation in response to diverse treatments. On the other hand, significant increases in α ‐amylase inhibitor activity and AAI levels were detected in leaves of insect‐damaged, MeJA‐ and ABA‐treated A. hypochodriacus plantlets, but not in those subjected to water‐ or salt‐stress. A differential induction of trypsin inhibitor activity and α ‐amylase inhibitor accumulation in response to insect herbivory by two related species of lepidopterous larvae was observed, whereas mechanical wounding failed to induce either inhibitor. The overall results suggest that trypsin and α ‐amylase inhibitors could protect A. hypochondriacus against multiple types of stress.