Lignification of the fruit endocarp layer occurs in many angiosperms and plays a critical role in seed protection and dispersal. This process has been extensively studied with relationship to pod shatter or dehiscence in Arabidopsis. Dehiscence is controlled by a set of transcription factors that define the fruit tissue layers and whether or not they lignify. In contrast, relatively little is known about similar processes in other plants such as stone fruits which contain an extremely hard lignified endocarp or stone surrounding a single seed.

The apricot species is characterized by a gametophytic self-incompatibility (GSI) system. While GSI is one of the most efficient mechanisms to prevent self-fertilization and increase genetic variability, it represents a limiting factor for fruit production in the orchards. Compatibility among apricot cultivars was usually assessed by either field pollination experiments or by histochemical evaluation of in vitro pollen tube growth. In apricots, self-compatibility is controlled by two unlinked loci, S and M, and associated to transposable element insertion within the coding sequence of SFB and ParM-7 genes, respectively. Self-compatibility has become a primary breeding goal in apricot breeding programmes, stimulating the development of a rapid and cost-effective marker assisted selection (MAS) approach to accelerate screening of self-compatible genotypes. In this work, we demonstrated the feasibility of a novel High Resolution Melting Analysis (HRMA) approach for the massive screening of self-compatible and self-incompatible genotypes for both S and M loci. The different genotypes were unambiguously recognized by HRMA, showing clearly distinguishable melting profiles. The assay was developed and tested in a panel of accessions and breeding selections with known self-compatibility reaction, demonstrating the potential usefulness of this approach to optimize and accelerate apricot breeding programmes.

The common bean (Phaseolus vulgaris L.) low phytic acid (lpa1) biofortified genotype produces seeds with improved nutritional characteristics and does not display negative pleiotropic effects. Here we demonstrated that lpa1 plants establish an efficient nitrogen-fixing symbiosis with Rhizobium etli CE3. The lpa1 nodules showed a higher expression of nodule-function related genes than the nodules of the parental wild type genotype (BAT 93). We analyzed the response to water stress of lpa1 vs. BAT 93 plants grown under fertilized or under symbiotic N₂-fixation conditions. Water stress was induced by water withholding (up to 14% soil moisture) to fertilized or R. etli nodulated plants previously grown with normal irrigation. The fertilized lpa1 plants showed milder water stress symptoms during the water deployment period and after the rehydration recovery period when lpa1 plants showed less biomass reduction. The symbiotic water-stressed lpa1 plants showed decreased nitrogenase activity that coincides with decreased sucrose synthase gene expression in nodules; lower turgor weight to dry weight (DW) ratio, which has been associated with higher drought resistance index; downregulation of carbon/nitrogen (C/N)-related and upregulation of stress-related genes. Higher expression of stress-related genes was also observed in bacteroids of stressed lpa1 plants that also displayed very high expression of the symbiotic cbb₃ oxidase (fixNd).

In peach, a long peduncle can help minimize mechanical damages/physical injuries in the fruit at harvest and can also be useful in postharvest handling and transportation. In view of genetically dissecting the peduncle length (PL) in peach, we have performed a Quantitative Trait Locus (QTL) mapping study for PL using a F₂ progeny of 117 individuals from the cross ‘PI 91459 [NJ Weeping]’ x ‘Bounty’ (WxBy). The progeny was phenotyped for three years (2011, 2012 and 2014) and the QTL mapping analysis was performed using four methods: Kruskall-Wallis, Interval Mapping, Multiple QTL Mapping and Genome-Wide Composite Interval Mapping. QTL analysis led to the identification of 9 QTLs distributed on linkage groups (LG) 1, 2, 4, 5, 6 and 7. A stable QTL was identified on LG6 (22,978,897 to 24,666,094 bp) and explained up to 63% of the phenotypic variance. Within the genetic interval of the stable QTL on LG6 potential candidate genes with functional annotation encompassing cellular expansion, hormone regulation, transcriptional regulation, developmental processes such as meristem development, and responses to environmental cues were found. The results reported in this study represent the first insight into the genetic basis of PL and a step forward towards the introduction of novel traits in peach commercial breeding in order to minimize the problems related to mechanical damage/injuries to peach fruits that commonly might occur during at harvest and post-harvest processes.