Glucosinolate translocation from inflorescences to stem during postharvest senescence of broccoli

CASAJÚS, VICTORIA; MARTINEZ, GUSTAVO A; GOMEZ LOBATO, EUGENIA

Congreso; XXXIV Argentinian Meeting of Plant Physiology; 2023

Broccoli's consumption contributes to the human diet compounds with beneficial effects on health. This vegetable - belonging to the Brassicas family - has a high content of antioxidants, vitamins and glucosinolates. Glucosinolates are secondary metabolites whose degradation products have biopesticide activity and have been shown to have a protective effect against various types of cancer. Broccoli is harvested manually and only the flower head is consumed disregarding the other tissues collected during harvest (stems and stalk). Once the harvest is done, the yellowing of the inflorescences begins, which causes both a nutritional and commercial loss of this vegetable. In this work, 15 heads of broccoli were harvested with the same stem length in order to study senescence in the different parts of the harvested organ. The heads were placed in plastic cups and stored at 20 °C for 5 days in the darkness. On day 0 (harvest day) and day 5 (final of harvest) the heads were divided into three sections: inflorescences (section 1: S1), the small stems (section 2: S2) and the main stem (section 3: S3). The three sections were cut in liquid nitrogen and then stored at -80 °C for posterior analysis. The content of individual glucosinolates was measured with a UPLC unit coupled to a mass spectrometer and the expression of the genes involved in the glucosinolate biosynthesis, degradation and transport pathways was analyzed by qRT-PCR. A sharp decrease in GLS content was detected in inflorescences, but a significant increase was found in the stems. Expression studies of genes coding for biosynthesis, degradation and transport strongly suggest that GLSs are transported from inflorescences to stems. rather than a de novo biosynthesis in stems or degradation in inflorescences. Taking into account this results could think use the stems in order to obtain bioactive components in order to improve the nutritional values of different food products.