We further investigated the role of the Arabidopsis CBF regulatory genes in cold acclimation, the process whereby certain plants increase in freezing tolerance upon exposure to low temperature. The CBF genes, which are rapidly induced in response to low temperature, encode transcriptional activators that control the expression of genes containing the C-repeat/ dehydration responsive element DNA regulatory element in their promoters. Constitutive expression of either CBF1 or CBF3 (also known as DREB1b and DREB1a, respectively) in transgenic Arabidopsis plants has been shown to induce the expression of target COR (cold-regulated) genes and to enhance freezing tolerance in nonacclimated plants. Here we demonstrate that overexpression of CBF3 in Arabidopsis also increases the freezing tolerance of cold-acclimated plants. Moreover, we show that it results in multiple biochemical changes associated with cold acclimation: CBF3-expressing plants had elevated levels of proline (Pro) and total soluble sugars, including sucrose, raffinose, glucose, and fructose. Plants overexpressing CBF3 also had elevated P5CS transcript levels suggesting that the increase in Pro levels resulted, at least in part, from increased expression of the key Pro biosynthetic enzyme ⌬ 1 -pyrroline-5-carboxylate synthase. These results lead us to propose that CBF3 integrates the activation of multiple components of the cold acclimation response.

mapping was done in a population of F 2 -derived lines developed by crossing a G. max experimental line and Increases in the seed protein concentration of soybean [Glycine a G. soja plant introduction. The QTL mapped to what max (L.) Merr.] would improve the value of the crop. Two major quantitative trait locus (QTL) alleles from Glycine soja Sieb. andwere then labeled linkage groups (LG) A and K of the Zucc. that increased seed protein concentration were identified pre-soybean map. The map has been revised and LG A has viously. The first objective of our study was to test the two G. soja QTL been renamed LG E, and LG K has been renamed LG alleles in a population developed through backcrossing the alleles into I (Shoemaker and Specht, 1995). Diers et al. (1992) a soybean background. The second objective was to evaluate the found that the G. soja allele for the most significant effect of one of the G. soja QTL alleles in three genetic backgrounds. marker from each LG was associated with an increase A backcross three (BC3) population was developed and evaluated in in protein concentration of 17 g kg Ϫ1 for LG A and 24 the field across two locations over 2 yr. To test the allele in different g kg Ϫ1 for LG K. The high protein alleles from G. soja backgrounds, a line from the backcross population was crossed to were associated with reduced oil concentration for three soybean genotypes. Populations developed from these crosses both QTL. were then evaluated in three field environments. In the backcross population, genetic marker alleles linked to the QTL allele from G. There have been other reports of genes controlling soja on linkage group (LG) I were significantly (P Ͻ 0.05) associated protein concentration mapping to the same region on with greater protein and less oil concentration, reduced yield, smaller LG I (previously LG K) as reported by Diers et al. seeds, taller plants, and earlier maturity than the G. max alleles. (1992). Brummer et al. (1997) mapped a QTL for in-Markers linked to the second G. soja QTL allele on LG E were not creased protein concentration to this region using a popsignificantly associated with seed or agronomic traits. In the genetic ulation in which one parent was 25% G. soja germplasm. background tests, markers linked to the G. soja QTL allele on LG This suggests that their high protein gene also came I were associated with an increase in protein concentration in two of from G. soja. Hegstad et al. (2000) mapped the wp locus, the three crosses. These results show that seed component traits can be which confers pink flower color in the presence of W1 successfully modified through genetic mapping coupled with marker (Stephens and Nickell, 1991), to the same region on LG assisted selection.

High-throughput genome scans are important tools for genetic studies and breeding applications. Here, a 6K SNP array for use with the Illumina Infinium® system was developed for diploid sweet cherry (Prunus avium) and allotetraploid sour cherry (P. cerasus). This effort was led by RosBREED, a community initiative to enable marker-assisted breeding for rosaceous crops. Next-generation sequencing in diverse breeding germplasm provided 25 billion basepairs (Gb) of cherry DNA sequence from which were identified genome-wide SNPs for sweet cherry and for the two sour cherry subgenomes derived from sweet cherry (avium subgenome) and P. fruticosa (fruticosa subgenome). Anchoring to the peach genome sequence, recently released by the International Peach Genome Initiative, predicted relative physical locations of the 1.9 million putative SNPs detected, preliminarily filtered to 368,943 SNPs. Further filtering was guided by results of a 144-SNP subset examined with the Illumina GoldenGate® assay on 160 accessions. A 6K Infinium® II array was designed with SNPs evenly spaced genetically across the sweet and sour cherry genomes. SNPs were developed for each sour cherry subgenome by using minor allele frequency in the sour cherry detection panel to enrich for subgenome-specific SNPs followed by targeting to either subgenome according to alleles observed in sweet cherry. The array was evaluated using panels of sweet (n = 269) and sour (n = 330) cherry breeding germplasm. Approximately one third of array SNPs were informative for each crop. A total of 1825 polymorphic SNPs were verified in sweet cherry, 13% of these originally developed for sour cherry. Allele dosage was resolved for 2058 polymorphic SNPs in sour cherry, one third of these being originally developed for sweet cherry. This publicly available genomics resource represents a significant advance in cherry genome-scanning capability that will accelerate marker-locus-trait association discovery, genome structure investigation, and genetic diversity assessment in this diploid-tetraploid crop group.

Striking increases in fruit size distinguish cultivated descendants from small-fruited wild progenitors for fleshy fruited species such as Solanum lycopersicum (tomato) and Prunus spp. (peach, cherry, plum, and apricot). The first fruit weight gene identified as a result of domestication and selection was the tomato FW2.2 gene. Members of the FW2.2 gene family in corn (Zea mays) have been named CNR (Cell Number Regulator) and two of them exert their effect on organ size by modulating cell number. Due to the critical roles of FW2.2/CNR genes in regulating cell number and organ size, this family provides an excellent source of candidates for fruit size genes in other domesticated species, such as those found in the Prunus genus. A total of 23 FW2.2/CNR family members were identified in the peach genome, spanning the eight Prunus chromosomes. Two of these CNRs were located within confidence intervals of major quantitative trait loci (QTL) previously discovered on linkage groups 2 and 6 in sweet cherry (Prunus avium), named PavCNR12 and PavCNR20, respectively. An analysis of haplotype, sequence, segregation and association with fruit size strongly supports a role of PavCNR12 in the sweet cherry linkage group 2 fruit size QTL, and this QTL is also likely present in sour cherry (P. cerasus). The finding that the increase in fleshy fruit size in both tomato and cherry associated with domestication may be due to changes in members of a common ancestral gene family supports the notion that similar phenotypic changes exhibited by independently domesticated taxa may have a common genetic basis.Electronic supplementary materialThe online version of this article (doi:10.1007/s11032-013-9872-6) contains supplementary material, which is available to authorized users.