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This study used the pathosystem of lettuce ( Lactuca spp.) and downy mildew ( Bremia lactucae) as a model to investigate the inheritance of nonhost resistance, and focused on the contribution of quantitative trait loci (QTLs) to nonhost resistance at various developmental stages in the lettuce life cycle. A set of 28 backcross inbred lines (BILs) of L. saligna CGN05271 (nonhost) introgressions in a L. sativa cv. Olof (host) background identified 16 introgressions that contributed to resistance at various plant developmental stages: seedlings, young plants, adult plants in the greenhouse and adult plants in the field. This paper provisionally considered these introgressions to be 16 QTLs. Of these 16 QTLs, seven were identified previously and nine were new. For 15 QTLs ( Rbq1, Rbq2, rbq3–7 and Rbq8–15), the resistance alleles were derived from the nonhost L. saligna; the resistance allele of the other QTL ( Rbq16) was from the susceptible L. sativa cv. Olof. Of the 15 QTLs in L. saligna, only two, rbq5 and rbq7, were found to be effective at every plant developmental stage; the other 13 QTLs were only effective at certain developmental stages. Experiments with seven B. lactucae races did not provide evidence that any QTL was race-specific. The data suggest that nonhost resistance in L. saligna is the result of cumulative effects of many resistance QTLs operating at various developmental stages. [ABSTRACT FROM AUTHOR]

Eating quality (EQ) of rice is mainly determined by sensory evaluation using tasting, which is affected by the taster's geographic residential area, gender, and age. The sensory evaluation protocol also requires rice samples (usually > 500 g) larger than the amount harvested from the early generations of breeding in many cases, thereby hindering the sensory tasting practices. The characteristics of rice starch have a significant impact on EQ; however, information on starch assisted-selection of EQ is insufficient. In this study, the recombinant inbred lines and backcross recombinant inbred lines constructed by the hybridization of japonica (O. sativa L. ssp. japonica) rice (cv. Toyonishiki) and indica (O. sativa L. ssp. indica) rice (cv. Qishanzhan) were used as test materials to analyze and explore the relationships between the amylose content (AC), rapid visco analyzer (RVA) profile characteristics, and the EQ score obtained from sensory tasting assessment. We provided a feasible solution to use rice starch properties to assist in selection of EQ. The results indicated that AC and RVA profile characteristics including trough viscosity (TV), final viscosity (FV), breakdown (BD), and setback (SB) were closely related to the EQ values. Furthermore, an integrated indicator—i.e., starch properties quality (SPQ)—that represented a more comprehensive characterization of rice starch, was derived based on the EQ evaluation hierarchy and weighted AC, TV, FV, BD, and SB values. The correlation between SPQ and EQ was significant (p < 0.001), and was significantly higher compared with using individual indicators. Moreover, the SPQ method requires less rice samples (i.e., 3 g of milled rice flour) and can be applied to assisted-selection for EQ in early generations of breeding. This study provid esessential technical support for the rapid and accurate identification of the EQ of progeny of indica–japonica hybrids. [ABSTRACT FROM AUTHOR]

Columnar growth in apples can have considerable positive consequences for orchard maintenance, but the lack of columnar cultivars producing fruits with desired market quality prevents their broader utilization in orchards. New crossings focused on their breeding are therefore conducted throughout the world every year. Unfortunately, the reliable discrimination between columnar growth and normal phenotype is difficult until seedlings are 2–3 years of age. However, molecular marker–assisted selection (MAS) can be used in seedlings several weeks old providing immense help in breeding programmes focused on columnar apple production. Here, we describe a rapid and reliable method for the detection of both wild‐type (WT) and columnar (Co) alleles originating from 'McIntosh Wijcik' in a single reaction using a real‐time PCR allelic discrimination approach. Our assay was tested in 130 genotypes (80 normal and 50 columnar habit) from various crossings and their parents, and in all cases, genotype corresponded to phenotype. The assay is thus suitable for laboratories interested in high‐throughput MAS for columnar tree habit breeding. [ABSTRACT FROM AUTHOR]

Breeders have long been interested in understanding the biological function and mechanism of xero-halophytes and their ability for growth in drought-stricken and salinized environments. However, the mechanisms in response to stress have been difficult to unravel because their defenses require regulatory changes to the activation of multiple genes and pathways. Metabolomics is becoming a key tool in comprehensively understanding the cellular response to abiotic stress and represents an important addition to the tools currently employed in genomics-assisted selection for plant improvement. In this review, we highlight the applications of plant metabolomics in characterizing metabolic responses to salt and drought stress, and identifying metabolic quantitative trait loci (QTLs). We also discuss the potential of metabolomics as a tool to unravel stress response mechanisms, and as a viable option for the biotechnological improvement of xero-halophytes when no other genetic information such as linkage maps and QTLs are available, by combining with germplasm-regression-combined marker-trait association identification. [ABSTRACT FROM AUTHOR]

Two intraspecific peach breeding populations have been used to conduct a quantitative trait locus (QTL) analysis of fruit quality traits: an F from the cross Bolero (B) x OroA (O) and an F from the cross Contender (C) x Ambra (A). A total of 344 Prunus simple sequence repeats (SSRs) were analyzed in B, O, C, A parents and CxA F hybrid. Eight SSR were mapped for the first time in peach. A multiplex-ready polymerase chain reaction (PCR) protocol has allowed considerable time and cost saving during genotyping steps. Two maps ( B map and O map) were produced for BxO population following the pseudo-test cross strategy and one for CxA. No marker could be mapped on G6 for the B map, on G4 and G8 for the O map and on G5 for the CxA map. Both populations were phenotyped over 2 years for maturity date (MD), fruit weight, external fruit skin overcolor, juice total soluble solids (SSC, Brix degree), juice titrable acidity and juice pH. Data for blooming time and flower type were scored only for BxO in 2007. All traits had a normal distribution, except for MD which was bimodal in BxO and trimodal in CxA, where it was scored as a co-dominant trait. Up to two QTLs per trait were detected in each population, and most of them were located in the same region forming clusters of QTLs, especially on G4. This is likely due to a major pleiotropic effect of MD masking the identification of other QTLs for different traits. [ABSTRACT FROM AUTHOR]