Molecular mapping of hypersensitive resistance from tomato 'Hawaii 7981' to Xanthomonas perforans race T3

Bacterial spot of tomato (Solanum lycopersicum) is caused by four species of Xanthomonas. The disease causes significant yield losses and a reduction in fruit quality. Physiological races have been described with tomato race 3 (T3) corresponding to strains of Xanthomonas perforans. The breeding line Hawaii 7981 (hereafter H7981) shows a hypersensitive reaction (HR) to race T3 strains conditioned by the interaction of the host resistance locus Xv3 and the bacterial effector avrXv3. The Xv3 gene is required for H7981-derived resistance to be effective under field conditions, though its expression is subject to genetic background. The segregation of HR in F(2) populations derived from H7981 crossed to processing tomato parents OH88119 and OH7870 was studied in 331 progeny, with the two independent crosses providing validation. We screened 453 simple-sequence repeat, insertion/deletion, and single-nucleotide polymorphism markers and identified 44 polymorphic markers each for the OH88119 and OH7870 populations covering 84.6 and 73.3% of the genome, respectively, within 20 centimorgans (cM). Marker-trait analysis using all polymorphic markers demonstrated that Xv3-mediated resistance maps to chromosome 11 in the two independent crosses. Allelism tests were conducted in crosses between lines carrying Xv3 derived from H7981, Rx-4 derived from plant introduction (PI) 128216, and resistance derived from PI 126932. These allelism tests suggested that the loci conditioning HR to race T3 strains are linked within 0.1 cM, are allelic, or are the same gene.     

Comment on "The geometry of musical chords"

Tymoczko (Reports, 7 July 2006, p. 72) proposed that the familiar sonorities of Western tonal music cluster around the center of a multidimensional orbifold. However, this is not true for all tonal progressions. When prototypical three-voice cadential progressions by Bach converge on the tonic, the chords migrate from the center to the edge of the orbifold.     

Political attitudes vary with physiological traits

Although political views have been thought to arise largely from individuals' experiences, recent research suggests that they may have a biological basis. We present evidence that variations in political attitudes correlate with physiological traits. In a group of 46 adult participants with strong political beliefs, individuals with measurably lower physical sensitivities to sudden noises and threatening visual images were more likely to support foreign aid, liberal immigration policies, pacifism, and gun control, whereas individuals displaying measurably higher physiological reactions to those same stimuli were more likely to favor defense spending, capital punishment, patriotism, and the Iraq War. Thus, the degree to which individuals are physiologically responsive to threat appears to indicate the degree to which they advocate policies that protect the existing social structure from both external (outgroup) and internal (norm-violator) threats.     

A tomato cysteine protease required for Cf-2-dependent disease resistance and suppression of autonecrosis

Little is known of how plant disease resistance (R) proteins recognize pathogens and activate plant defenses. Rcr3 is specifically required for the function of Cf-2, a Lycopersicon pimpinellifolium gene bred into cultivated tomato (Lycopersicon esculentum) for resistance to Cladosporium fulvum. Rcr3 encodes a secreted papain-like cysteine endoprotease. Genetic analysis shows Rcr3 is allelic to the L. pimpinellifolium Ne gene, which suppresses the Cf-2-dependent autonecrosis conditioned by its L. esculentum allele, ne (necrosis). Rcr3 alleles from these two species encode proteins that differ by only seven amino acids. Possible roles of Rcr3 in Cf-2-dependent defense and autonecrosis are discussed.     

Building Community Capacity through Enhanced Collaboration in the Farmers Market Nutrition Program

The Farmers Market Nutrition Program (FMNP) is a federal-state partnership designed to provide fresh, locally grown produce to low-income participants at nutritional risk and expand consumer awareness and use of local produce sold at farmers markets. This paper describes the results of a collaboration initiative based on the typology of a “comprehensive, multisectorial collaboration” to support the FMNP. We report the outcomes of the partnerships that developed over three years, including increased outreach to FMNP participants and strategies to decrease barriers to participation. Those partnerships that reached higher degrees of coordination or collaboration are now addressing market accessibility and market quality in new ways. Those partnerships that exhibited the highest degree of collaboration are contributing to community capacity building beyond FMNP issues per se and to larger issues affecting the agriculture community and the food security of residents. Jamie S. Dollahite, PhD, RD, is an associate professor of Community Nutrition. She leads the Food and Nutrition Education in Communities programs, including Cornell Cooperative Extension’s role in the Farmers Market Nutrition Program, which provide outreach to and conduct research with limited resource audiences across New York State. Janet A. Nelson, MS Ed, is an Extension associate in Community Nutrition. Since 1999 she has coordinated Cornell Cooperative Extension’s role in the New York State Farmers Market Nutrition Program. For the preceding five years, Janet was Rural and Community Nutrition Educator for Cornell Cooperative Extension of Oswego County where she facilitated Extension’s relationship with the NYS-FMNP at the county level. Edward A. Frongillo, PhD, is an associate professor of Community and International Nutrition. His work includes the evaluation of program enhancements for the Farmers Market Nutrition Program, as well as studying the impact of nutrition programs for elders on food security, dietary intake, and nutritional status. Matthew Griffin, MS, is the Nutrition Resource Manager at the Food Bank of the Southern Tier, Elmira, New York where he coordinates nutrition, food safety, and community food security programs in connection with emergency food relief organizations.     

Crystal structure of human toll-like receptor 3 (TLR3) ectodomain

Toll-like receptors (TLRs) play key roles in activating immune responses during infection. The human TLR3 ectodomain structure at 2.1 angstroms reveals a large horseshoe-shaped solenoid assembled from 23 leucine-rich repeats (LRRs). Asparagines conserved in the 24-residue LRR motif contribute extensive hydrogen-bonding networks for solenoid stabilization. TLR3 is largely masked by carbohydrate, but one face is glycosylation-free, which suggests its potential role in ligand binding and oligomerization. Highly conserved surface residues and a TLR3-specific LRR insertion form a homodimer interface in the crystal, whereas two patches of positively charged residues and a second insertion would provide an appropriate binding site for double-stranded RNA.