SUMMARY Germplasm of Brachypodium distachyon was inoculated with Magnaporthe grisea using either rice- (Guy11) or grass-adapted (FAG1.1.1, PA19w-06, PA31v-01) host-limited forms of the fungus, and interactions with varying degrees of susceptibility and resistance were identified. Ecotype ABR5 was resistant to each M. grisea strain whereas ABR1 was susceptible to all but P31vi-01. Mendelian segregation in ABR1 x ABR5 crosses suggested that a single dominant resistance gene conferred resistance to Guy11. Microscopic analyses revealed that the aetiology of Guy11 fungal development and disease progression in ABR1 closely resembled that of rice infections. In ABR5, Guy11 pathogenesis was first suppressed at 48 h post-inoculation, at the secondary hyphal formation stage and was coincident with cytoplasmic granulation. Resistance to strains PA31v-01 and FAG1.1.1 was associated with a localized cell death with little callose deposition. 3,3-Diaminobenzidine staining indicated the elicitation of cell death in B. distachyon was preceded by oxidative stress in the interacting epidermal cells and the underlying mesophyll cells. Northern blot hybridization using probes for barley genes (PR1, PR5 and PAL) indicated that each was more rapidly expressed in ABR5 challenged with Guy11 although the B. distachyon defence genes BD1 and BD8 were more quickly induced in ABR1. Such data show that B. distachyon is an appropriate host for functional genomic investigations into M. grisea pathology and plant responses.

In 2000, the Social Security system experienced an annual net inflow of over $150 billion, raising its balance to over one trillion dollars. Once the baby boom generation begins to retire, however, the annual surpluses will almost certainly turn into deficits, and the trust funds are predicted to be exhausted in 2038. Investing part of the trust funds in equities would increase the expected returns and thus improve the system's expected long-term finances. But with higher expected returns comes higher risk: Equity investment could potentially leave the system worse off. This paper uses the Long-Term Actuarial Model developed by the Congressional Budget Office to analyze both the higher expected returns and the additional uncertainty that accompany equity investment, while recognizing that uncertainty already exists in the system due to unpredictable demographic and economic factors. We find that there is a clear risk-return tradeoff in the short term, but that (given a consistent policy of equity investment) the magnitude of risk falls substantially over a 75-year horizon.