A novel ethylene receptor homolog gene isolated from ethylene-insensitive flowers of gladiolus (Gladiolus grandiflora hort.)

https://doi.org/10.1016/j.bbrc.2006.10.111Get rights and content

Abstract

Gladiolus is an ethylene insensitive flower whose exogenous ethylene and ethylene inhibitors have no effect on the petal senescence process. To study which processes in gladiolus are associated with changes in ethylene perception, two types of gladiolus genes, named GgERS1a and GgERS1b, respectively, homologous to the Arabidopsis ethylene receptor gene ERS1 were isolated. GgERS1a is conserved in terms of exon numbers and intron positions, whereas GgERS1b is almost same with GgERS1a except lacking 636 nucleotide encoding first and second histidine kinase (HisKA) motifs. The sequence data on full length genomic DNA indicated that both GgERS1a and b were spliced from different genomic DNA. As the result of mRNA expression study, in spite of lacking the two significant motifs, the expression of GgERS1b dramatically changed with advance in petal senescence, whereas the level of GgERS1a expressed highly and constitutively. The result suggests that both the genes possess a significant role for the subfunctionalization process to provide ethylene insensitivity in gladiolus flowers.

Section snippets

Materials and methods

Plant materials and genomic DNA extraction. Gladiolus grandiflora hort cv. Traveler. (4x = 2n = 60) were grown in compost in a greenhouse condition. For expression analysis, flowers, at five distinct developmental stages from buds open to senescence, were collected and the different tissues were frozen in liquid nitrogen and stored at −80 °C until each analysis. Extraction of genomic DNA from young leaves of gladiolus was performed by DNeasy Plant Maxi Kit (Qiagen Co., Hilden, Germany) according to

Characterization of GgERS1a and GgERS1b

We isolated two gladiolus full-length cDNA homologues of the Arabidopsis ethylene receptor gene by 5′ and 3′ RACE-PCR. These two homologues have strong similarity to the amino acid sequences both of Arabidopsis thaliana AtERS1 as dicotyledon and Oryza sativa OsERS1 as monocotyledon (Fig. 1). One cDNA coding region was 1905 nucleotide in length and its open reading frame encoded 634 amino acids, and the other was 1269 nucleotide and 422 amino acids (Fig. 2A). The both deduced amino acid

Discussion

We isolated the GgERS1a and GgERS1b genes from a tetraploid plant, gladiolus. The predicted amino acid sequences of GgERS1a and GgERS1b were similar to that of Arabidopsis ERS1 gene encoding an ethylene receptor kinase [5], [6], [7]. The predicted GgERS1a protein was conserved at important domains such as TM, GAF, and HisKA, and at residues thought to be important for the normal function of ERS1 (residues Ala31, Ile62, Cys65, and Ala102, which correspond to the positions that are mutated in the

Acknowledgment

This work was supported by a research fellowship from the Japanese Society for Promotion of Sciences (JSPS), Japan.

References (20)

There are more references available in the full text version of this article.

Cited by (0)

1

Present address: Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi 110 012, India.

2

These authors equally contributed to this work.

View full text