Molecular Landscape of Bolting in Spinach Explored Through Gene Expression Profiling

This study aims to investigate the molecular mechanisms governing bolting in spinach (Spinacia oleracea) by analyzing gene expression patterns in key regulatory pathways. Two cultivars, Kashan (early bolting) and Virofly (late-bolting), were analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) at different developmental stages. The photoperiod pathway genes Cryptochrome2 (CRY2) and Flavin-binding kelch repeat F-box protein (FKF1) showed distinct expression dynamics, highlighting their roles in the vegetative-to-reproductive transition. Aging pathway genes Topless (TPL), Squamosa promoter binding protein5 (SPL5), SPL15, and Alpha-ketoglutarate-dependent dioxygenase AlkB-like (AlkB) revealed complex expression patterns, with SPL5 and SPL15 differing significantly in Virofly. Circadian pathway genes LATE ELONGATED HYPOCOTYL (LHY) and TIMING OF CAB EXPRESSION 1 (TOC1) showed distinct patterns, particularly LHY in Kashan. Autonomous pathway genes LUMINIDEPENDENS (LD) and FLOWERING LOCUS D (FLD) also varied, with LD higher in Kashan at the eight-leaf stage, while FLD was generally elevated. These findings provide insights into the interactions among photoperiod, aging, circadian, and autonomous pathways, suggesting regulatory mechanisms influencing bolting time. Further research into these pathways could enhance spinach breeding for improved yield and quality.