Using a combination of approaches, three EIN3-like (EIL) genes DC-EIL1/2 (AY728191), DC-EIL3 (AY728192), and DC-EIL4 (AY728193) were isolated from carnation (Dianthus caryophyllus) petals. DC-EIL1/2 deduced amino acid sequence shares 98% identity with the previously cloned and characterized carnation DC-EIL1 (AF261654), 62% identity with DC-EIL3, and 60% identity with DC-EIL4. DC-EIL3 deduced amino acid sequence shares 100% identity with a previously cloned carnation gene fragment, Dc106 (CF259543), 61% identity with Dianthus caryophyllus DC-EIL1 (AF261654), and 59% identity with DC-EIL4. DC-EIL4 shared 60% identity with DC-EIL1 (AF261654). Expression analyses performed on vegetative and flower tissues (petals, ovaries, and styles) during growth and development and senescence (natural and ethylene-induced) indicated that the mRNA accumulation of the DC-EIL family of genes in carnation is regulated developmentally and by ethylene. DC-EIL3 mRNA showed significant accumulation upon ethylene exposure, during flower development, and upon pollination in petals and styles. Interestingly, decreasing levels of DC-EIL3 mRNA were found in wounded leaves and ovaries of senescing flowers whenever ethylene levels increased. Flowers treated with sucrose showed a 2 d delay in the accumulation of DC-EIL3 transcripts when compared with control flowers. These observations suggest an important role for DC-EIL3 during growth and development. Changes in DC-EIL1/2 and DC-EIL4 mRNA levels during flower development, and upon ethylene exposure and pollination were very similar. mRNA levels of the DC-EILs in styles of pollinated flowers showed a positive correlation with ethylene production after pollination. The cloning and characterization of the EIN3-like genes in the present study showed their transcriptional regulation not previously observed for EILs.

To observe changes in the nutritional status of corollas during development and senescence, Petunia ×hybrida 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.

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Changes in ethylene responsiveness of senescence-related (SR) genes in carnation (Dianthus caryophyllus cv. White Sim) petals were investigated during flower development. Dose-response and time-response analysis of SR gene expression indicate that SR genes can be divided into two groups according to their response to ethylene. The ethylene biosynthetic genes, ACC synthase and ACC oxidase represent one group. They show a marked delay of 6 and 9 h in mRNA accumulation in response to ethylene and their apparent dissociation constants of the response (K r ) at open flower stage of development are 17.20 and 1.76 ml l ª1 ,

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