Agrobacterium rhizogenes-mediated transformation has been used to obtain transgenic plants in 89 different taxa, representing 79 species from 55 genera and 27 families. A diverse range of dicotyledonous plant families is represented, including one Gymnosperm family. In addition to the Ri plasmid, over half these plants have been transformed with foreign genes, including agronomically useful traits. Plants regenerated from hairy roots often show altered plant morphology such as dwarfing, increased rooting, altered flowering, wrinkled leaves and/or increased branching due to rol gene expression. These altered phenotypic features can have potential applications for plant improvement especially in the horticultural industry where such morphological alterations may be desirable. Use of A. rhizogenes and rol gene transformation has tremendous potential for genetic manipulation of plants and has been of particular benefit for improvement of ornamental and woody plants.

The development of a fungal endophyte in the tissue of Lolium perenne during flowering, seed set, and germination is described. The endophyte progresses intercellularly from the vegatative apex into/t~ inflorescence primordium and floral apices, from where it penetrates the tissues of ovary and ovule. At megagametophyte maturity, hyphae are concentrated outside its wall adjacent to the large lateral antipodal cells and subsequently gain entry to the embryo sac, probably soon after fertilisation. During early embryogenesis, hyphae occur on the surface of the embryo, and penetrate it at the 'notched' stage. At seed maturity, hyphae are widespread within the embryo, including the plumule apex, as well as below the testa, between cells of the aleurone layer, and between scutellum and endosperm. At germination, hyphae outside the embryo appear to play no further part in invasion of the already infected embryo. The endophyte of Festuca arundinacea has a similar relationship with its host and appears to be ultrastructurally indistinguishable from that of Lolium perenne.

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An aleurain-like protein, BoCP5, is up-regulated during harvest-induced senescence in broccoli floret and leaf tissue. BoCP5 is most closely related to an Arabidopsis protein (91%, AAF43041) and has 71% identity to barley aleurain (P05167). The mRNA for this gene accumulates within 6 h after harvest in broccoli florets, and its expression is reduced in tissue that has been held in senescence-delaying treatments (e.g. water, sucrose feeding, controlled atmosphere). The gene is also expressed in leaves during aging-related and harvest-induced senescence. Analysis of protein bands that cross-react with antibodies raised to the bacterial BoCP5 fusion protein, revealed prominent immunoreactive bands at ca. 26, 28, 31, and 38 kD in floret tissue. The 31 kD band was absent in protein extracts from leaf tissue. Agrobacterium-mediated transformation was used to produce transgenic broccoli plants with down-regulated BoCP5. A reduction in the postharvest expression of BoCP5 in floret tissue was achieved for four transgenic lines in the current study. In three of these lines postharvest floret senescence (yellowing) was delayed, and florets contained significantly greater chlorophyll levels during postharvest storage at 20 degrees C than wild-type plants. Line 4 showed the greatest down-regulation of BoCP5, and in this line postharvest protease activity remained at pre-harvest levels, and the yield of soluble proteins extracted from florets after harvest was significantly greater than that of wild-type tissue.

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