Cross-Species Comparison of Fruit-Metabolomics to Elucidate Metabolic Regulation of Fruit Polyphenolics Among Solanaceous Crops.

Many solanaceous crops are an important part of the human daily diet. Fruit polyphenolics are plant specialized metabolites that are recognized for their human health benefits and their defensive role against plant abiotic and biotic stressors. Flavonoids and chlorogenates are the major polyphenolic compounds found in solanaceous fruits that vary in quantity, physiological function, and structural diversity among and within plant species. Despite their biological significance, the elucidation of metabolic shifts of polyphenols during fruit ripening in different fruit tissues, has not yet been well-characterized in solanaceous crops, especially at a cross-species and cross-cultivar level. Here, we performed a cross-species comparison of fruit-metabolomics to elucidate the metabolic regulation of fruit polyphenolics from three representative crops of Solanaceae (tomato, eggplant, and pepper), and a cross-cultivar comparison among different pepper cultivars (Capsicum annuum cv.) using liquid chromatography-mass spectrometry (LC-MS). We observed a metabolic trade-off between hydroxycinnamates and flavonoids in pungent pepper and anthocyanin-type pepper cultivars and identified metabolic signatures of fruit polyphenolics in each species from each different tissue-type and fruit ripening stage. Our results provide additional information for metabolomics-assisted crop improvement of solanaceous fruits towards their improved nutritive properties and enhanced stress tolerance.

Genome-wide association and gene validation studies for early root vigour to improve direct seeding of rice.

Elucidation of the genetic control of rice seedling vigour is now paramount with global shifts towards direct seeding of rice and the consequent demand for early vigour traits in breeding programmes. In a genome-wide association study using an indica-predominant diversity panel, we identified quantitative trait loci (QTLs) for root length and root number in rice seedlings. Among the identified QTLs, one QTL for lateral root number on chromosome 11, qTIPS-11, was associated with a 32.4% increase in lateral root number. The locus was validated in independent backgrounds, and a predicted glycosyl hydrolase, TIPS-11-9, was identified as the causal gene for observed phenotypic differences. TIPS-11-9 was differentially expressed in emerging lateral roots of contrasting qTIPS-11 haplotypes, which was likely due to differences in cis-regulatory elements and auxin responsiveness. Abolishment of Tips-11-9 function through T-DNA insertion in a qTIPS-11-positive background resulted in a reduction of lateral root number, which negatively affected biomass accumulation, particularly under phosphorous-limiting conditions. Marker-assisted introgression of qTIPS-11 into modern indica varieties will aid in the generation of varieties adapted to direct seeding and thus facilitate the adoption of direct seeding practices in tropical Asia.