Gibberellin mobilizes distinct DELLA-dependent transcriptomes to regulate seed germination and floral development in Arabidopsis - PubMed (original) (raw)

Gibberellin mobilizes distinct DELLA-dependent transcriptomes to regulate seed germination and floral development in Arabidopsis

Dongni Cao et al. Plant Physiol. 2006 Oct.

Abstract

Severe Arabidopsis (Arabidopsis thaliana) gibberellin (GA)-deficient mutant ga1-3 fails to germinate and is impaired in floral organ development. In contrast, the ga1-3 gai-t6 rga-t2 rgl1-1 rgl2-1 mutant confers GA-independent seed germination and floral development. This fact suggests that GA-regulated transcriptomes for seed germination and floral development are DELLA dependent. However, it is currently not known if all GA-regulated genes are GA regulated in a DELLA-dependent fashion and if a similar set of DELLA-regulated genes is mobilized to repress both seed germination and floral development. Here, we compared the global gene expression patterns in the imbibed seeds and unopened flower buds of the ga1-3 mutant with that of the wild type and of the ga1-3 gai-t6 rga-t2 rgl1-1 rgl2-1 mutant. We found that about one-half of total GA-regulated genes are apparently regulated in a DELLA-dependent fashion, suggesting that there might be a DELLA-independent or -partially-dependent component of GA-dependent gene regulation. A cross-comparison based on gene identity revealed that the GA-regulated DELLA-dependent transcriptomes in the imbibed seeds and flower buds are distinct from each other. Detailed ontology analysis showed that, on one hand, DELLAs differentially regulate the expression of different individual members of a gene family to run similar biochemical pathways in seeds and flower. Meanwhile, DELLAs control many functionally different genes to run specific pathways in seeds or flower buds to mark the two different developmental processes. Our data shown here not only confirm many previous reports but also single out some novel aspects of DELLA functions that are instructive to our future research.

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Figures

Figure 1.

Figure 1.

RT-PCR confirmation of DELLA-down and DELLA-up genes in the imbibed seeds. A, DELLA-down genes. B, DELLA-up genes. RT-PCR analysis was repeated on three independent samples and a representative ethidium bromide gel picture is shown here. Corresponding gene locus identity (Gene ID) is provided. Two genes (At1g21680 and At3g22490) in B were confirmed in only one of the three repeats but not in other two repeats and were marked with an asterisk. Primer pairs for each individual gene are listed in Supplemental Table S7. penta: ga1-3 gai-t6 rga-t2 rgl1-1 rgl2-1 penta mutant. ACT2 (ACTIN 2 gene) and UBQ10 (UBIQUITIN 10 gene) were used as the normalization controls.

Figure 2.

Figure 2.

RT-PCR confirmation of DELLA-down and DELLA-up genes in the unopened young flower buds. A, DELLA-down genes. B, DELLA-up genes. RT-PCR analysis was repeated on three independent samples and a representative ethidium bromide gel picture is shown here. Corresponding gene locus identity (Gene ID) is provided. Two genes (At1g09970 and At2g04240) in B did not show obvious difference in expression and were marked with an asterisk. Primer pairs for each individual gene are listed in Supplemental Table S12. penta: ga1-3 gai-t6 rga-t2 rgl1-1 rgl2-1 penta mutant. ACT2 (ACTIN 2 gene) was used as the normalization control.

Figure 3.

Figure 3.

RT-PCR confirmation of shared DELLA-down and DELLA-up genes in the imbibed seeds and young flower buds. A, Shared-DELLA-down genes. B, Shared-DELLA-up genes. RT-PCR analysis was repeated on three independent samples and a representative ethidium bromide gel picture is shown here. Corresponding gene locus identity (Gene ID) is provided. Three shared DELLA-down genes and two shared DELLA-up genes showed no difference in expression in the young flower buds and imbibed seeds, respectively, and these genes were marked with an asterisk. Primer pairs for each individual gene are listed in Supplemental Table S13. penta: ga1-3 gai-t6 rga-t2 rgl1-1 rgl2-1 penta mutant. For the imbibed seeds, ACT2 (ACTIN 2 gene) and UBQ10 (UBIQUITIN 10 gene) were used as the normalization controls. For the young flower buds, ACT2 was used as the normalization control.

Figure 4.

Figure 4.

Amino acid sequence alignment of rice GID1 with its three Arabidopsis homologs (At3g05120, At3g63010, and At5g27320) using the ClustalW program. Gene ID is provided on the left side of the figure.

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