To study the function of bean rust haustoria either the host, Phaseolus vulgaris, or the parasite, Uromyces phaseoli, were labeled with 3H-lysine. 24h and 48 h after inoculation samples of the infected leaves were taken and processed for electronmicroscopic autoradiography. When the host was labeled, silver grain densities over the structures of host and parasite were compared. Very low grain d...

Host genetic resistance is a key component of integrated pest management. The present authors and others are investigating the use of RNA interference (RNAi) as a genetic tool for engineering host resistance against parasitic weeds. The general approach is to transform a host plant with a plasmid encoding a double stranded hairpin RNA (hpRNA) targeted against one or more vital parasite genes. W...

To directly address the function of a putative auxin receptor designated ABP1, a reverse genetic approach was taken to identify and characterize ABP1 mutant alleles in Arabidopsis. A homozygous null mutation in ABP1 confers embryo lethality. Null mutant embryos develop normally until the early stages of the globular embryo but are unable to make the transition to a bilaterally symmetrical struc...

The MADS domain protein AGL15 (AGAMOUS-Like 15) has been found to preferentially accumulate in angiosperm tissues derived from double fertilization (i.e. the embryo, suspensor, and endosperm) and in apomictic, somatic, and microspore embryos. Localization to the nuclei supports a role in gene regulation during this phase of the life cycle. To test whether AGL15 is involved in the promotion and ...

Rust fungi have a complex life cycle (see Littlefield 1981) and produce different spore forms. The basidiospores, aeciospores and uredospores develop highly specialized infection structures in order to penetrate into the leaf. The germ tune of the dikaryotic uredospore follows the array of wax crystals on the cuticle in a typical way and grows towards a stoma (Fig la). When the tip of the germ ...

The pattern of expression of two genes coding for proteins rich in proline, HyPRP (hybrid proline-rich protein) and HRGP (hydroxyproline-rich glycoprotein), has been studied in maize (Zea mays) embryos by RNA analysis and in situ hybridization. mRNA accumulation is high during the first 20 d after pollination, and disappears in the maturation stages of embryogenesis. The two genes are also expr...