Association mapping has been proposed as an efficient approach to assist plant breeding programs to investigate the genetic basis of agronomic traits. In this study, we evaluated 18 traits related to yield, (FWP, NF, FWI, and FWII), fruit size-shape (FP, FA, MW, WMH, MH, HMW, DI, FSI, FSII, OVO, OBO), and fruit quality (FIR, CF, and SST), in a diverse collection of 100 accessions of Physalis peruviana including wild, landraces, and anther culture derived lines. We identified seven accessions with suitable traits: fruit weight per plant (FWP) > 7,000 g/plant and cracked fruits (CF) < 4%, to be used as parents in cape gooseberry breeding program. In addition, the accessions were also characterized using Genotyping By Sequencing (GBS). We discovered 27,982 and 36,142 informative SNP markers based on the alignment against the two cape gooseberry references transcriptomes. Besides, 30,344 SNPs were identified based on alignment to the tomato reference genome. Genetic structure analysis showed that the population could be divided into two or three sub-groups, corresponding to landraces-anther culture and wild accessions for K = 2 and wild, landraces, and anther culture plants for K = 3. Association analysis was carried out using a Mixed Linear Model (MLM) and 34 SNP markers were significantly associated. These results reveal the basis of the genetic control of important agronomic traits and may facilitate marker-based breeding in P. peruviana.

The cape gooseberry (Physalis peruviana L.) is one of the most important Colombian exotic fruits. Chromosome doubling of anther-derived plants is a key factor in the application of double haploid technology for the genetic improvement of crops. In the present study, axillary buds from four haploid cape gooseberry genotypes were used to evaluate artificial chromosome doubling induced by colchicine and its effects on ploidy level and pollen fertility. Three concentrations of colchicine (5, 10 and 15 mM) and three exposure times (2, 4 and 6 h) were used to determine the best treatment for the generation of fertileB plants from axillary buds of haploid genotypes. The colchicine increased both the number of chromosomes, from 36 to 129, and the average chloroplasts in stomata guard cell, from 4.5 to 23.8. The optimal chromosome doubling of the haploids was obtained with the 5 mM colchicine solution and 2 h exposure time. This protocol produced chromosome doubling in over 60% of the regenerants of the four haploid genotypes, with a high level of fertility. Morphologically, the fertile mixoploid plants showed variation in the vegetative, flowering and fruit characteristics, as compared to the haploid plants.

The cape gooseberry, Physalis peruviana L., is a crop that is transitioning from a semi-wild rural food source to becoming an international export commodity fruit deserving of greater attention from the scientific community, producers, policy makers and opinion makers. Despite its importance, the crop has serious technological development challenges, mainly associated with the limited supply of genetically improved materials for producers and consumers. In the present study, the level of ploidy of 100 genotypes of gooseberry from a working collection was determined by counting the number of chromosomes and chloroplasts, to include them in the breeding program. The number of chromosomes in dividing cells of root-tip meristems, as well as the number of chloroplasts per guard cell, from plants grown in vitro and ex vitro conditions were determined. Haploid with 24 chromosomes, doubled haploid-tetraploid with 48 chromosomes, aneuploid (44 and 49 chromosomes) and mixoploid genotypes with 36 to 86 chromosomes were found. The number of chloroplasts / cell guard ranged from 4-8, 6-16, 7-16 and 9-21 for the haploid, aneuploid, doubled haploid-tetraploid and mixoploid genotypes, respectively. Evidence of a high cytogenetic diversity in the evaluated genotypes.

Cape gooseberry (Physalis peruviana, L.) is a herbaceous plant belonging to the Solanaceae family that produces an edible berry appreciated for its nutraceutical and pharmaceutical properties. Its production is often limited by diseases and reproducible fruit quality. Recent studies have reported genes associated with fruit quality and resistance response to the root-infecting fungus Fusarium oxysporum f. sp. physali (Foph,) which causes vascular wilt. In order to standardize a method to validate the biological function of candidate genes in the non-model species P. peruviana, we tested the robust approach in reverse genetics, virus induced gene silencing (VIGS). In this study, we validated and optimized VIGS using an insert of the phytoenedesaturase (PDS) gene in a silencing viral vector generated from tobacco rattlevirus (TRV). Leaves infiltrated with Agrobacterium (GV3101 strain) showed photo-bleached segments, which were distinctive for PDS suppression at 7 days post-infection (dpi). More than half of the treated plants showed photo bleaching, indicating an efficiency rate of 50 % of the VIGS protocol. The results of this study showed that VIGS can be used for future functional gene characterization implicated in the immune response, disease resistance and fruit quality in capegooseberry.

1 Simposio Intenacional y 2 Nacional de Ciencias Agronómicas: El renacer del espacio de discusión científica para el Agro colombiano.