Management of the Tolerance to Bolting for Spinach (Spinacia Oleracea L.): Retrospect and Prospects

Abstract

Spinach (Spinacia oleracea L.) is an important and nutritious green leafy vegetable, and there are rich carotenoids, folate, vitamin C, calcium and iron in spinach. The yields of spinach were approach 28 million tons in 2017 all over the world (FAO). However, the earlier bolting is one of the important limiting factors affecting the quality and yield in spinach, and it is an instant task to preventing the earlier bolting and creating the bolting tolerance germplasm resources in spinach breeding. The evaluation criteria is essential to determine whether it has entered the reproductive stage and to judge the timing of harvesting or breeding, but the evaluation criteria for the bolting trait in spinach had not been established yet. Bolting is controlled by some endogenous and environmental factors. The bolting variation provided extremely rich resources in spinach, and the abiotic stresses could induce bolting and the biochemical regulations such as endogenous and exogenous hormones could also influence the bolting mechanism.A diverse range of endogenous and environmental signals regulates bolting, and these signals are integrated into a single decision. The study on bolting characteristics was summarized in terms of factors influencing bolting and inheritance of bolting characteristics, to serve as reference for the further study in spinach. Because of its sensitivity to photoperiod, long-day exposure induces bolting in spinach, which is not good for the year-round production in spinach. Manipulating the day length and temperature during the growing process of spinach can prevent bolting. The previous studies showed that bolting tolerance is associated with an expression of an integrative gene network involved in environmental perception, hormone signalling, and flowering in the shoot apical meristem. However, the genotypic tolerance to bolting, particularly important for breeders, is still poorly understood in spinach. This review on bolting trait may lay the foundation for bolting-resistant breeding in spinach.