A regulatory gene induces trichome formation and embryo lethality in tomato

Abstract

Trichomes are universal biological structures originating from the aerial epidermis, which serve as an excellent model to study plant differentiation at the cell level. Although the pathway regulating trichome formation in the Rosids has been well characterized, only very recently a few genes were identified for trichome initiation in the Asterids. In this study, we cloned Woolly (Wo), essential for trichome formation in tomato. Transgenic experiments revealed that the woolly phenotype is caused by the mutation in Wo which encodes a homeodomain protein containing a bZIP motif and a START domain. We identified three alleles of Wo and found that each allele contains a missense mutation, which respectively results in an amino acid substitution at the C terminus. Microarray and expression analysis showed that the expression of a B-type cyclin gene, SlCycB2, is possibly regulated by Wo, which also participates in trichome formation. Suppression of Wo or SlCycB2 expression by RNAi decreased the number of type I trichomes, and direct protein-protein interaction was detected between them, implying that both proteins may work together in the regulation of this type of trichome formation. Cytological observation and Wo transcript analysis in the developing seeds showed that embryo development was also correlated with Wo.cell cycle | multicellular trichome

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…However, their transcriptional levels were not altered significantly in response to the overexpression of a Wo v transgene, which induced a clear trichome proliferation phenotype. On the contrary, homologs of genes (Wo and SlCycB2) involved in trichome formation in asterids (Yang et al, 2011a(Yang et al, , 2011b were significantly up-regulated in Wo v transgenic N. tabacum plants .…”

“…The woolly (Wo) gene, encoding a class IV homeodomain-Leu zipper protein homolog to the Arabidopsis GL2, and a B-type cyclin gene, SlCycB2 (possibly regulated by Wo), control the initiation and development of type I trichomes. Mutant alleles of Wo triggered a hairy phenotype due to the overproduction of type I trichomes, while suppression of Wo or SlCycB2 expression by RNA interference decreased their density in tomato (Yang et al, 2011a(Yang et al, , 2011b. Another mutation (hairless) affects the SRA1 (Specifically Rac1-Associated protein) subunit of the WAVE regulatory complex.…”

A genome-wide survey of homeodomain-leucine zipper genes and analysis of cold-responsive HD-Zip I members’ expression in tomato

“…The atml1/pdf2 double mutant never forms an organized protodermal layer in the apical part of proembryo. [30][31][32][33] ANL2 plays a role in the accumulation of anthocyanin and cellular organization of the primary root. 32) Wo is a GL2-like HD-Zip IV protein of tomato, which is important to trichome formation.…”

“…48,49) SlHZ11 (Wo, woolly) and SlHZ45 were clustered with PDF2, HDG2, and ATML1 in the same clade ε, which suggested that these genes of this clade might played an important role in epidermal cell fate. 33,[50][51][52][53] CD2 gene is another HD-Zip IV member of tomato in α clade, which is associated with cutin deficiency in tomato fruit and preferentially expressed in epidermal cells of tomato stems. CD2 is a homolog of Arabidopsis ANTHOCYANINLESS2 (ANL2).…”

“…Wo gene interacted with cell cycle gene SLCycB2 to promote the transit from G2 to M. Wo homozygote caused tomato embryo lethal. 33) Tomato is an important agricultural and economic crop, also a significant model plant in investigating evolution, genetics, and other basic biological research. After completion of tomato whole genomic sequencing, 34) classification and function of large number of genes will be predicted and identified.…”