Endogenous Plant Hormone Profiles in Growing Melon Fruit

Abstract

Melon is a crucial cultivar in the Cucurbitaceae family and is the third most-produced in the world (FAO, 1994). Thus, different phytochemical regulators have been examined to produce high-quality fruits, develop labor-saving and low-cost cultivation methods: promotion of fruit set by synthetic cytokinins, 6-benzylaminopurine (BA) (Jones, 1965), and acceleration of fruit set by 1(2-Chloro4-pyridinyl) -3-phenylurea (CPPU) (Li et al., 2002); increase of sucrose concentration by synthetic auxin, pchlorophenoxyacetic acid (p-CPA) (Hayata et al., 2002). Additionally, the mechanism of this formation is not clear despite a unique net is generated in Earls melons. Fruit growth is regulated by various plant hormones (Gillaspy et al. 1993). Therefore, analysis of the endogenous amounts of major plant hormones will lead to the elucidation of developmental physiology and the development of techniques for overcoming physiological disorders. The following studies are known on the levels of endogenous hormones in melon fruits: analysis of indole-3acetic acid (IAA) at 5─35DAF (days after flowering) in seeds and pulp by high performance liquid chromatography (HPLC) with a fluorescence detector (Lee et al., 1997); analysis of abscisic acid (ABA) at 20─60 DAF seeds and pulp by enzyme linked immune sorbent assay (ELISA) (Welbaum et al., 2000); gas chromatographymass spectrometry (GC-MS) analysis of IAA and ABA for 10 days after treatment with synthetic cytokinin on flowering (Hayata et al., 2002). It has also reported that analysis of IAA, ABA and gibberellin (GA) in the rind, pulp and placenta of seeded and non-seeded grape cultivars by HPLC (Wang et al., 1993). However, there is no report on the simultaneous analysis of major phytohormones of each tissue in growing melon fruit by the current reliable mass detector. Therefore, in this study, eight major endogenous hormones, IAA, ABA, trans-zeatin (tZ), isopentenyl adenine (iP), jasmonic acid (JA), methyl jasmonate (MeJA), and GA (GA1, GA4) were concurrently quantified by instrumental analysis. This study is elucidate the phytohormone profiles at various stages during melon fruit growth.