Nodal distribution of free polyamines in cotton ovaries

Abstract

SUMMARYThe nodal distribution of free polyamines (important regulators of flower induction) in cotton (Gossypium hirsutum L.) ovaries was determined by high-performance liquid chromatography (HPLC). The objective of the study was to investigate the nodal distribution of putrescine (Put), spermidine (Spd) and spermine (Sp) of cotton lines (G. hirsutum L.), and to determine whether there are differences in ovarian polyamine content among three commercial cotton cultivars. A field study was conducted in 2005 and 2006 using the cultivars FM960BR, ST5599BR and DP444BR. Free polyamines Put, Spd and Sp were determined in ovarian tissue of first-position white flowers starting at the beginning of anthesis and collected from the 7th, 9th, 11th and 13th main-stem nodes for four consecutive weeks. There was no significant nodal position by cultivar interaction; thus, the main effects were tested. Put content decreased acropetally along the main stem of the cotton plant with the highest content observed at the 7th node and the lowest at the 13th node. Spd content decreased below and above the 9th node, with the 9th node showing the highest amount of Spd and the 13th node the lowest in both years of the study. Similarly, Sp content decreased below and above the 9th node. In general, the 7th and the 9th node had the highest titre of free polyamines. Among the cultivars tested, FM960BR showed higher polyamine content in one season; however, the observation was not consistent from year to year. The highest amounts of polyamines were observed at the 7th and the 9th node of cotton and this may be associated with the known yield distribution: almost 0·80 of the total yield of cotton is derived from these nodal positions.