Changes in Mineral Nutrient Concentrations in Petunia Corollas during Development and Senescence

Abstract

<jats:p>To observe changes in the nutritional status of corollas during development and senescence, <jats:italic>Petunia</jats:italic> ×<jats:italic>hybrida</jats:italic> cv. Mitchell corollas were analyzed for macronutrient and micronutrient content, dry weight, fresh weight, and ethylene production. Carbon content decreased at slightly lower rates than dry weight during corolla development between anthesis and senescence, while fresh weight and ethylene production followed patterns expected of climacteric flowers. Nitrogen, phosphorus, and potassium content declined during development. Both phosphorus and potassium content gradually declined throughout development with overall losses of about 75% and 40%, respectively. Nitrogen content declined 50% during development but losses occurred only during the final stages of senescence. No significant changes were observed in sulfur, calcium, magnesium, and micronutrient content of the corollas during development. Most elements were present in much lower concentrations in corollas than in leaves. The concentrations of calcium, magnesium, and manganese were about 1-, 5-, and 15-fold lower in corollas than in leaves, respectively. Results indicate that remobilization of selected macronutrients from corollas occurred before and during senescence. Taken together with the presence of low concentrations of macronutrients, my data support the contention that petunia corollas are nutritionally in expensive and therefore easily disposable organs.</jats:p>

Mineral nutrient remobilization during corolla senescence in ethylene-sensitive and -insensitive flowers

“…A number of experiments evaluating nutrient changes during flower development have been conducted in Petunia × hybrida (Verlinden 2003; Chapin and Jones 2007, 2009). Petunia is often used as a model for ethylene-sensitive flower senescence (Jones et al 2009).…”

“…Petunia is often used as a model for ethylene-sensitive flower senescence (Jones et al 2009). Senescing, unpollinated petunia flowers show visual symptoms of corolla wilting, concomitant with decreases in FW at 6–10 days after anthesis, depending on growing conditions (Verlinden 2003). Decreases in petunia petal DW during senescence are not as extensive as those in daylily, and they retain ∼65 % of their maximum DW (Verlinden 2003).…”

“…developmental or age-related senescence) is accompanied by decreases in the N and P content of the corollas (Verlinden 2003; Chapin and Jones 2009). A gradual decline in P throughout development begins well before visual symptoms of wilting or losses in FW.…”

“…Once the flower has been pollinated, or the stigma is no longer receptive to pollination, the corolla senesces (Jones 2002). Senescence is the last stage of flower development, during which nutrients are recycled to developing tissues (Bieleski 1995; Verlinden 2003; Chapin and Jones 2007; Trivellini et al 2011). A genetically controlled senescence programme allows the plant to systematically disassemble cellular organelles and macromolecules, and remobilize nutrients from the petals before cell death.…”

“…Common features of petal senescence include losses of cellular organization, increases in membrane permeability and degradation of organelles (Smith et al 1992; O'Donoghue et al 2002; Wagstaff et al 2003). This is accompanied by the increased export of carbohydrates (especially sucrose), macro- and micro-nutrients; decreased nucleic acid and protein content; increased DNA fragmentation; and increased mRNA abundance and enzyme activity of proteases, nucleases and lipases (Bieleski 1995; Stephenson and Rubinstein 1998; Wagstaff et al 2002; Verlinden 2003; Jones et al 2005; Langston et al 2005; Pak and van Doorn 2005; Yamada et al 2006; Chapin and Jones 2007; Battelli et al 2011). There is increasing ultrastructural evidence and gene expression data indicating that autophagy occurs during petal senescence, but it is unclear if this is required for cell death (Shibuya et al 2011).…”