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Abstract  Sulphur (S) has become a major limiting factor for plant production in industrial as well as in remote industrial rural areas. Limitation of S can reduce legume N2 fixation by affecting nodule development and function. In pot experiments with pea (Pisum sativum L.) and alfalfa (Medicago sativa L.), we investigated the influence of S on growth, ferredoxin, ATP and leghemoglobin concentrations. Addition of 200 mg S pot−1 increased yield of shoots, roots and nodules of both plant species significantly. However, the influence of S on nodule yield formation was most pronounced. Pea and alfalfa roots were found to have higher S concentrations than shoots and being up to 2.9 times the S concentration in the shoots of peas under S-sufficient conditions. Sulphur addition also increased N2 fixation significantly. The ferredoxin concentration in bacteroids of root nodules of pea was increased significantly by S only 10 weeks after planting and in bacteroids of root nodules of alfalfa 10 and 17 weeks after planting, while on per pot base the amounts of ferredoxin were higher throughout the experimental period of time. The ATP concentration of bacteroids of root nodules of both plant species as well as of mitochondria of root nodules of pea were significantly higher with optimum S supply. The effects of S deficiency on N2 fixation are likely to be caused by the shortage of ferredoxin and ATP. The amount of leghemoglobin was reduced in comparison to nodules of the S-sufficient plants. [ABSTRACT FROM AUTHOR]

Summary.??Doratomyces stemonitis(Hyphomycetales, Dematiaceae) is a saprotrophic fungus belonging to the mycobiota of the cereal rhizosphere. The fungus is able to metabolize benzoxazolin-2-(3H)-one and a variety of its derivatives including higher plant detoxification products, microbial degradation products and the chemically rather stable 2-amino-(3H)-phenoxazin-3-one. D.stemonitiscan use all of these compounds as sole C-sources but their utilization, especially that of microbial degradation products and 2-amino-(3H)-phenoxazin-3-one, seems to be highly energy consuming, resulting in slow mycelium growth and a change of colony morphology. Benzoxazolin-2-(3H)-one derived compounds induce the synthesis of different isoforms of a glycosylated protein with sequence homologies to the endo-1,3-?-glucanase Asp f2, an allergen fromAspergillus fumigatusand other Asp f2-like proteins e.g., fromVerticillium dahliaeor PRA1 antigen fromCandida albicans. The induction of the protein is regarded as a stress response. [ABSTRACT FROM AUTHOR]

Abstract??Benzoxazolinone detoxification is similar in plants grown under sulfur deficiency conditions and in control plants grown with an optimal S supply. However, when S-deficient plants were treated with metolachlor before benzoxazolin-2(3H)-one (BOA) incubation, detoxification was reduced, as indicated by a lower accumulation of the detoxification products BOA-6-O-glucoside and glucoside carbamate and by a loss of BOA-6-OH glucosyltransfease activity. Root colonizing microorganisms and the endophytic fungusFusarium verticillioidesparticipated in benzoxazolinone detoxification by converting the compound to 2-acetamidophenol (AAP) orO-hydroxyphenyl malonamic acid (OHPMA), a process accompanied by the appearance of phenoxazinone. Maize roots, however, absorbed AAP and OHPMA only in traces. Absorbed traces of OHPMA stimulated maize radicle growth, and traces of AAP stimulated cress. Phenoxazinone inhibited the growth of cress radicles at concentrations higher than 500??M, whereas maize radicles were hardly affected.F. verticillioidesdid not convert benzoxazolinone to any known microbial degradation product when the medium of maize seedlings was inoculated with the fungus under sterile condition. Plant?fungus interactions seem to be important in plant survival of allelopathic attacks. This study points to a complicated network of allelopathic interactions that are influenced by biotic and abiotic factors, including herbicides. [ABSTRACT FROM AUTHOR]