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Transcriptome analysis of Arabidopsis wild-type and gl3-sst sim trichomes identifies four additional genes required for trichome development.

Marks MD, Wenger JP, Gilding E, Jilk R, Dixon RA - Mol Plant (2009)

Bottom Line: Mutations in this gene did not alter trichome expansion, but did alter mature trichome cell walls.Mutations in BLT resulted in a loss of trichome branch formation.Mutations in PEL3, which was previously shown to be required for development of the leaf cuticle, resulted in the occasional tangling of expanding trichomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Biology, University of Minnesota, St Paul, MN 551108, USA. marks004@umn.edu

ABSTRACT
Transcriptome analyses have been performed on mature trichomes isolated from wild-type Arabidopsis leaves and on leaf trichomes isolated from the gl3-sst sim double mutant, which exhibit many attributes of immature trichomes. The mature trichome profile contained many highly expressed genes involved in cell wall synthesis, protein turnover, and abiotic stress response. The most highly expressed genes in the gl3-sst sim profile encoded ribosomal proteins and other proteins involved in translation. Comparative analyses showed that all but one of the genes encoding transcription factors previously found to be important for trichome formation, and many other trichome-important genes, were preferentially expressed in gl3-sst sim trichomes. The analysis of genes preferentially expressed in gl3-sst sim led to the identification of four additional genes required for normal trichome development. One of these was the HDG2 gene, which is a member of the HD-ZIP IV transcription factor gene family. Mutations in this gene did not alter trichome expansion, but did alter mature trichome cell walls. Mutations in BLT resulted in a loss of trichome branch formation. The relationship between blt and the phenotypically identical mutant, sti, was explored. Mutations in PEL3, which was previously shown to be required for development of the leaf cuticle, resulted in the occasional tangling of expanding trichomes. Mutations in another gene encoding a protein with an unknown function altered trichome branch formation.

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Characterization of the pel3 Mutant.(A) Wrinkled leaf phenotype of pel3-11 seedling.(B) Co-grown wild-type Col seedling.(C, D) Higher magnification of wrinkled leaf showing tangled trichomes in (D).(E) Wild-type Col inflorescence.(F) pel 3–11 inflorescence showing lack of expanded petals.(G) Dissected pel3-11 flower showing trapped petals, anthers, and pollen grains.(H, I) DIC and fluorescent images of pel3-11 trichomes expressing gfp-PEL3 fusion protein. N highlights position of the nucleus in (H) and (I).
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fig6: Characterization of the pel3 Mutant.(A) Wrinkled leaf phenotype of pel3-11 seedling.(B) Co-grown wild-type Col seedling.(C, D) Higher magnification of wrinkled leaf showing tangled trichomes in (D).(E) Wild-type Col inflorescence.(F) pel 3–11 inflorescence showing lack of expanded petals.(G) Dissected pel3-11 flower showing trapped petals, anthers, and pollen grains.(H, I) DIC and fluorescent images of pel3-11 trichomes expressing gfp-PEL3 fusion protein. N highlights position of the nucleus in (H) and (I).

Mentions: The results above indicate that comparative analyses should be useful for identifying new trichome mutants. Given that 11 of 12 transcription factors required for trichome formation showed enhanced expression in gl3–sst sim trichomes compared to processed shoots, we chose to look for new mutants by identifying additional transcription factors up-regulated in the mutant. Transcription factor genes expressed in the double mutant trichomes but not in processed shoots were ranked by expression level (Table 4). Within the top 10 genes, seven of the transcription factors important for trichome formation were re-identified. To hunt for additional trichome genes, T-DNA insertion lines were obtained from the Arabidopsis stock center corresponding to other genes in the list. Stocks obtained for AGL14 (CS841281) and AGL19 (SALK_000234) did not reveal the presence of trichome mutants; however, insertions in HDG2 resulted in trichome abnormalities. This mutant is shown in Figure 4, and will be discussed in more detail below. An expanded mutant search was conducted by ranking all genes detected in the double mutant but not in processed shoot. Seeds with T-DNA inserts within the most highly ranked genes were screened for trichome defects. This analysis identified two additional new mutants as shown in Figures 5B and 6, and studied in more detail below. Finally, as noted above, the ranking of genes most highly expressed in gl3–sst sim revealed that genes ranked two and three were known to be associated with trichomes. Therefore, we obtained T-DNA insertional lines for the most highly expressed gene. Indeed, these lines also contained mutants with altered trichomes, as shown in Figure 5C.


Transcriptome analysis of Arabidopsis wild-type and gl3-sst sim trichomes identifies four additional genes required for trichome development.

Marks MD, Wenger JP, Gilding E, Jilk R, Dixon RA - Mol Plant (2009)

Characterization of the pel3 Mutant.(A) Wrinkled leaf phenotype of pel3-11 seedling.(B) Co-grown wild-type Col seedling.(C, D) Higher magnification of wrinkled leaf showing tangled trichomes in (D).(E) Wild-type Col inflorescence.(F) pel 3–11 inflorescence showing lack of expanded petals.(G) Dissected pel3-11 flower showing trapped petals, anthers, and pollen grains.(H, I) DIC and fluorescent images of pel3-11 trichomes expressing gfp-PEL3 fusion protein. N highlights position of the nucleus in (H) and (I).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2713768&req=5

fig6: Characterization of the pel3 Mutant.(A) Wrinkled leaf phenotype of pel3-11 seedling.(B) Co-grown wild-type Col seedling.(C, D) Higher magnification of wrinkled leaf showing tangled trichomes in (D).(E) Wild-type Col inflorescence.(F) pel 3–11 inflorescence showing lack of expanded petals.(G) Dissected pel3-11 flower showing trapped petals, anthers, and pollen grains.(H, I) DIC and fluorescent images of pel3-11 trichomes expressing gfp-PEL3 fusion protein. N highlights position of the nucleus in (H) and (I).
Mentions: The results above indicate that comparative analyses should be useful for identifying new trichome mutants. Given that 11 of 12 transcription factors required for trichome formation showed enhanced expression in gl3–sst sim trichomes compared to processed shoots, we chose to look for new mutants by identifying additional transcription factors up-regulated in the mutant. Transcription factor genes expressed in the double mutant trichomes but not in processed shoots were ranked by expression level (Table 4). Within the top 10 genes, seven of the transcription factors important for trichome formation were re-identified. To hunt for additional trichome genes, T-DNA insertion lines were obtained from the Arabidopsis stock center corresponding to other genes in the list. Stocks obtained for AGL14 (CS841281) and AGL19 (SALK_000234) did not reveal the presence of trichome mutants; however, insertions in HDG2 resulted in trichome abnormalities. This mutant is shown in Figure 4, and will be discussed in more detail below. An expanded mutant search was conducted by ranking all genes detected in the double mutant but not in processed shoot. Seeds with T-DNA inserts within the most highly ranked genes were screened for trichome defects. This analysis identified two additional new mutants as shown in Figures 5B and 6, and studied in more detail below. Finally, as noted above, the ranking of genes most highly expressed in gl3–sst sim revealed that genes ranked two and three were known to be associated with trichomes. Therefore, we obtained T-DNA insertional lines for the most highly expressed gene. Indeed, these lines also contained mutants with altered trichomes, as shown in Figure 5C.

Bottom Line: Mutations in this gene did not alter trichome expansion, but did alter mature trichome cell walls.Mutations in BLT resulted in a loss of trichome branch formation.Mutations in PEL3, which was previously shown to be required for development of the leaf cuticle, resulted in the occasional tangling of expanding trichomes.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Biology, University of Minnesota, St Paul, MN 551108, USA. marks004@umn.edu

ABSTRACT
Transcriptome analyses have been performed on mature trichomes isolated from wild-type Arabidopsis leaves and on leaf trichomes isolated from the gl3-sst sim double mutant, which exhibit many attributes of immature trichomes. The mature trichome profile contained many highly expressed genes involved in cell wall synthesis, protein turnover, and abiotic stress response. The most highly expressed genes in the gl3-sst sim profile encoded ribosomal proteins and other proteins involved in translation. Comparative analyses showed that all but one of the genes encoding transcription factors previously found to be important for trichome formation, and many other trichome-important genes, were preferentially expressed in gl3-sst sim trichomes. The analysis of genes preferentially expressed in gl3-sst sim led to the identification of four additional genes required for normal trichome development. One of these was the HDG2 gene, which is a member of the HD-ZIP IV transcription factor gene family. Mutations in this gene did not alter trichome expansion, but did alter mature trichome cell walls. Mutations in BLT resulted in a loss of trichome branch formation. The relationship between blt and the phenotypically identical mutant, sti, was explored. Mutations in PEL3, which was previously shown to be required for development of the leaf cuticle, resulted in the occasional tangling of expanding trichomes. Mutations in another gene encoding a protein with an unknown function altered trichome branch formation.

Show MeSH