William A Cress

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In many plants, free proline accumulates in response to the imposition of a wide range of biotic and abiotic stresses. Controversy has surrounded the extent to which this shift in nitrogen metabolism benefits plants under adverse environmental conditions. Most attempts to account for the phenomenon have focused on the ability of proline to mediate osmotic(More)
The biochemical basis of heat/drought tolerance was investigated by comparing the response of antisense and sense transgenic soybean plants (containing the L-delta1-pyrroline-5-carboxylate reductase gene) with non-transgenic wild-type plants. The plants were subjected to a simultaneous drought and heat stress of 2 days, whereafter they were rewatered at 25(More)
Cytokinin (CK) levels tend to decrease under adverse environmental conditions. A general view has emerged that during stress, a reduction of CK supply from the root alters gene expression in the shoot and thereby elicits appropriate responses to ameliorate the effects of stress. However, recent studies have indicated that transcription of many(More)
Analysis of the rate-limiting dehydrogenases of the oxidative pentosephosphate pathway (OPPP), as well as changes in the contributions of14C1- and 14C6-labelled glucose torespired CO2 during germination, indicated activation of the OPPPduring Arabidopsis seed germination. An approximatelyfour-fold increase in free proline (Pro) was also observed prior to(More)
The potential value of proline accumulation during environmental stressreveals a collection of controversial statements. Some argue that prolineaccumulation is beneficial to the plant, while others suggest the oppositeto be true. It is thus still unknown whether or not a constitutive higherlevel of proline accumulation enhances plant tolerance to(More)
Kinetics of P absorption were investigated in mycorrhizal (Glomus fasciculatus) and nonmycorrhizal tomato (Lycopersicon esculentum) roots to determine why increased ion absorption by mycorrhizae occurs. Initial rates of absorption of (32)P were measured at 1 to 100 micromolar KH(2)PO(4) (pH 4.6). Absorption rates of mycorrhizae were about twice those of(More)
In vitro cultures of O. reclinata accumulate red anthocyanin pigments. Two callus lines were established from O. reclinata, one red and the other non-pigmented. The red callus accumulated cyanidin-3-glucoside as a major pigment. Light irradiation induced anthocyanin synthesis in white callus, resulting in a heterogenous red callus line being formed. The(More)
Δ1-pyrrolline-5-carboxylate reductase (EC 1.5.1.2; P5CR) catalyses the final step in proline biosynthesis from glutamate and ornithine, where Δ1-pyrrolline-5-carboxylate acts as an intermediate. In this study, differential accumulation of mRNA transcript encoding P5CR was investigated in tissues of the flowering stem of mature Arabidopsis thaliana (L.)(More)
Dimethylallyl pyrophosphate: L-tryptophan dimethylallyltransferase (dimethylallyl tryptophan synthetase) has been purified from Claviceps strain SD58 to a homogeneous crystalline form. The enzyme is pure as judged by polyacrylamide gel electrophoresis and contains two similar subunits of 34,000 molecular weight as shown by electrophoresis in polyacrylamide(More)
In vitro shoot organogenesis from Arabidopsis hypocotyl explants was stimulated by 1 mMproline, and to a lesser extent by 5 mM proline, butinhibited by inclusion of 10 mM proline in thehormonally-supplemented regeneration medium. Theability of low concentrations of the prolineanalogues, azetidine-2-carboxylate and thioproline toovercome the stimulatory(More)