Plants associate with a wide range of mutualistic and parasitic biotrophic organisms. Here, we investigated whether beneficial plant symbionts and biotrophic pathogens induce distinct or overlapping regulatory pathways in Medicago truncatula. The symbiosis between Sinorhizobium meliloti and this plant results in the formation of nitrogen-fixing root nodules requiring the activation of specific ...

Baccharis dracunculifolia, the host plant of the gall maker Neopelma baccharidis Burck., is locally distributed in delimited patches. The effects of the host plant individual (plant height, crown diameter, and crown volume), local (host plant patch), and regional (locality) characteristics on the number of galls were analyzed, in Viçosa (three patches) and in Rio Doce State Park, Marliéria (two...

Agrobacterium tumefaciens and Agrobacterium rhizogenes transfer plasmid-encoded genes and virulence (Vir) proteins into plant cells. The transferred DNA (T-DNA) is stably inherited and expressed in plant cells, causing crown gall or hairy root disease. DNA transfer from A. tumefaciens into plant cells resembles plasmid conjugation; single-stranded DNA (ssDNA) is exported from the bacteria via a...

Introduction: Plant galls are insect-induced tumor-like growths of plant tissue which nourish and protect developing gall former larvae (1). Gall inducers are typically host specific (2). The morphology of galls produced is unique to each gall former species and reflects the expression of both insect and host plant genomes (3). For each species of gall inducer, gall size at maturity varies wide...

Meloidogyne spp. are recognized worldwide as causing root galls on a wide range of plants. They have also been reported to cause galls on above-ground parts of 26 plant species in 22 genera, either under natural field conditions or after artificial inoculation (2,3,5,8,10-13). We observed galls containing root-knot nematodes on inflorescences and leaves of Palisota barteri Hook. f. in a Florida...

Galls induced by Meloidogyne spp. in plant roots are a complex organ formed by heterogeneous tissues; within them there are 5-8 giant cells (GCs) that root-knot nematodes use for their own nurturing. Subtle regulatory mechanisms likely mediate the massive gene repression described at early infection stages in galls, particularly in giant cells. Some of these mechanisms are mediated by microRNAs...

The plant-endoparasitic nematode Anguina pacificae is presently one of the most destructive pests of Poa annua in Northern California, causing stem galls at the base of tillers in this annual bluegrass, resulting in yellow or brown patches and irregular surfaces on golf course putting greens. The objective of the study was to investigate the population dynamics of A. pacificae on two golf cours...

The Plant Vigor Hypothesis (PVH) predicts an oviposition preference of females and higher offspring performance for insect herbivores on longer and fast-growing plant modules. We tested the PVH predictions by investigating the effects of leaf size of Miconia prasina (Sw.) DC. (Melastomataceae) on the oviposition preference and on the offspring survival of the gall-inducing weevil Prospoliata bi...

At least two species of aphid, Tamalia coweni and Tamalia dicksoni (Hemiptera: Aphididae) induce galls on the leaves of Arctostaphylos spp. shrubs (Ericaceae). These galls are frequently inhabited by at least one species of congeneric inquiline. The inquiline clade has branched off from the gall-inducing clade and appears to be radiating rapidly on different host-plants, in contrast to the gall...

Foraging, defense and waste disposal are essential for sustaining social insect colonies. Hence, their nest generally has an open structure, wherein specialized castes called workers and soldiers perform these tasks. However, some social aphids form completely closed galls, wherein hundreds to thousands of insects grow and reproduce for several months in isolation. Why these social aphids are n...