Dry legumes are staple and potentially functional food, being a good source of polyphenols, flavonoids, and antioxidant activity. The objective of this study was to determine the total polyphenol content (TPC), total flavonoid content (TFC), and their relation with antioxidant capacity in 17 chickpea lines having colored seed coats (black, red, brown, green, rubiginous, gray, yellow, cream, or beige). The seed coat usually contains more than 95% of these compounds. In this study, both TPC and TFC varied significantly among different lines and were highly correlated to antioxidant activity. Colored seeds contained up to 13-, 11-, and 31-fold more TPC, TFC, and antioxidant activity, respectively, than cream- and beige-color seeds. Thus, colored chickpea could be a potentially functional food in addition to its traditional role of providing dietary proteins and dietary fibers.

The two cDNAs coding for the cytosolic (cyt) and the chloroplast-located (chl) Cu,Zn superoxide dismutases (SODs) of tomato (Perl-Treves et al. 1988) were cloned into respective binary vectors and mobilized into Agrobacterium strains. Potato tuber discs were infected with either of the two agrobacterial strains and cultured on selective medium containing kanaymcin. The integration of either of the cyt or the chl SOD transgenes was verified by Southern-blot hybridization. The enzymatic activity of the additional tomato chl Cu,Zn SOD could be distinguished from endogenous SOD activity since the latter isozyme migrated faster on SOD-activity gels. Several transgenic potato lines harboring either the cyt or the chl SOD genes of tomato showed elevated tolerance to the superoxide-generating herbicide paraquat (methyl viologen). After exposure of shoots to paraquat, tolerance was recorded either by scoring symptoms visually or by measurements of photosynthesis using the photoacoustic method. Root cultures from transgenic lines that harbored the additional cyt Cu,Zn SOD gene of tomato were tolerant to methyl viologen up to 10(-5) M; a lower tolerance was recorded in roots of transgenic lines that expressed the additional chl Cu,Zn SOD of tomato.

Transcripts for two genes expressed early in alfalfa nodule development (MsENOD40 and MsENOD2) are found in mycorrhizal roots, but not in noncolonized roots or in roots infected with the fungal pathogen Rhizoctonia solani. These same two early nodulin genes are expressed in uninoculated roots upon application of the cytokinin 6-benzylaminopurine. Correlated with the expression of the two early nodulin genes, we found that mycorrhizal roots contain higher levels of trans-zeatin riboside than nonmycorrhizal roots. These data suggest that there may be conservation of signal transduction pathways between the two symbioses-nitrogen-fixing nodules and phosphate-acquiring mycorrhizae.Of the two commonly described symbioses of roots-nitrogenfixing nodules in response to members of Rhizobiaceae or Frankiaceae and phosphate-acquiring arbuscular mycorrhizae (AM) between roots and endophytic fungi-the more ancient of the two is AM. Structures identified as arbuscules have been found in Aglaophyton major, an early Devonian land plant, providing evidence for at least a Ͼ400-million-year-old association between terrestrial plants and fungi (1). In contrast, the Rhizobium-legume symbiosis is much younger, having been established no more than 65 to 136 million years ago, when the angiosperms evolved. However, unlike the AM symbiosis, which is found in almost all angiosperm families, Rhizobiuminduced nitrogen-fixing symbioses appear to be restricted to a single subclade of a larger nitrogen-fixing clade (2).LaRue and Weeden (3) proposed that nodulation evolved from the more ancient AM association because of certain similarities between the two symbioses. For example, some legumes are Nod Ϫ (absence of nodule formation) as well as Myc Ϫ

The development of leaf disease symptoms and the accumulation of pathogenesis-related (PR) proteins were monitored in leaves of tobacco (Nicotiana tabacum cv. Xanthinc) plants colonized by the arbuscular mycorrhizal fungus Glomus intraradices. Leaves of mycorrhizal plants infected with the leaf pathogens Botrytis cinerea or tobacco mosaic virus showed a higher incidence and severity of necrotic lesions than those of nonmycorrhizal controls. Similar plant responses were obtained at both low (0.1 mM) and high (1.0 mM) nutritional P levels and with mutant plants (NahG) that are unable to accumulate salicylic acid. Application of PR-protein activators induced PR-1 and PR-3 expression in leaves of both nonmycorrhizal and mycorrhizal plants; however, accumulation and mRNA steady-site levels of these proteins were lower, and their appearance delayed, in leaves of the mycorrhizal plants. Application of 0.3 mM phosphate to the plants did not mimic the delay in PR expression observed in the mycorrhizal tobacco. Together, these data strongly support the existence of regulatory processes, initiated in the roots of mycorrhizal plants, that modify disease-symptom development and gene expression in their leaves.

Some transgenic crops can introgress genes into other varieties of the crop, to related weeds or themselves remain as 'volunteer' weeds, potentially enhancing the invasiveness or weediness of the resulting offspring. The presently suggested mechanisms for transgene containment allow low frequency of gene release (leakage), requiring the mitigation of continued spread. Transgenic mitigation (TM), where a desired primary gene is tandemly coupled with mitigating genes that are positive or neutral to the crop but deleterious to hybrids and their progeny, was tested as a mechanism to mitigate transgene introgression. Dwarfism, which typically increases crop yield while decreasing the ability to compete, was used as a mitigator. A construct of a dominant ahasR (acetohydroxy acid synthase) gene conferring herbicide resistance in tandem with the semidominant mitigator dwarfing Delta gai (gibberellic acid-insensitive) gene was transformed into tobacco (Nicotiana tabacum). The integration and the phenotypic stability of the tandemly linked ahasR and Delta gai genomic inserts in later generations were confirmed by polymerase chain reaction. The hemizygous semidwarf imazapyr-resistant TM T1 (= BC1) transgenic plants were weak competitors when cocultivated with wild type segregants under greenhouse conditions and without using the herbicide. The competition was most intense at close spacings typical of weed offspring. Most dwarf plants interspersed with wild type died at 1-cm, > 70% at 2.5-cm and 45% at 5-cm spacing, and the dwarf survivors formed no flowers. At 10-cm spacing, where few TM plants died, only those TM plants growing at the periphery of the large cultivation containers formed flowers, after the wild type plants terminated growth. The highest reproductive TM fitness relative to the wild type was 17%. The results demonstrate the suppression of crop-weed hybrids when competing with wild type weeds, or such crops as volunteer weeds, in seasons when the selector (herbicide) is not used. The linked unfitness would be continuously manifested in future generations, keeping the transgene at a low frequency.

The broad host range of arbuscular mycorrhizal (.4M) fungi differs from the specificity encountered in biotrophic pathogens. We summarize here the basic plant strategies of defence plant responses to colonization -with pathogenic micro-organisms and evaluate their possible involvement in AM performance. Detailed evidence ts presented that, during early colonization of plant roots by symbiotic Glomus, defence-related root responses are induced and then subsequently suppressed. In AM interactions, the broad host-range infection capacity and the induction of defence-related genes suggests that the compatible interaction is dominant. These results are discussed in relation to the possible conclusion that AM fungi might Jack avirulence homologues or alternatively, that the factor causing suppression of the host defence response might be dominant.

ABSTRACT

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