The 14–Amino Acid CLV3, CLE19, and CLE40 Peptides Trigger Consumption of the Root Meristem in Arabidopsis through a CLAVATA2-Dependent Pathway

CLAVATA3 (CLV3), CLV3/ESR19 (CLE19), and CLE40 belong to a family of 26 genes in Arabidopsis thaliana that encode putative peptide ligands with unknown identity. It has been shown previously that ectopic expression of any of these three genes leads to a consumption of the root meristem. Here, we show that in vitro application of synthetic 14–amino acid peptides, CLV3p, CLE19p, and CLE40p, corresponding to the conserved CLE motif, mimics the overexpression phenotype. The same result was observed when CLE19 protein was applied externally. Interestingly, clv2 failed to respond to the peptide treatment, suggesting that CLV2 is involved in the CLE peptide signaling. Crossing of the CLE19 overexpression line with clv mutants confirms the involvement of CLV2. Analyses using tissue-specific marker lines revealed that the peptide treatments led to a premature differentiation of the ground tissue daughter cells and misspecification of cell identity in the pericycle and endodermis layers. We propose that these 14–amino acid peptides represent the major active domain of the corresponding CLE proteins, which interact with or saturate an unknown cell identity-maintaining CLV2 receptor complex in roots, leading to consumption of the root meristem

Protocol of anther and microspore culture in cassava (androgenesis) = Protocolo para el cultivo de anteras y microsporas (androgénesis) en yuca/mandioca

This 9-minute video describes the protocol used for the collection of male flowers in cassava for the production of doubled haploids through androgenesis (in vitro microspore or anther culture). Pre-treatments and different culture conditions used in the process to induce cell division in immature microspores are described. Progress inducing cell division and calli was made, but no plants could be regenerated. Este video de 9 minutos describe el protocolo usado en la colección de flores masculinas de yuca/mandioca para la producción de doble haploides a través de androgénesis (cultivo de microsporas o anteras). Se muestran algunos de los pre-tratamientos así como condiciones de cultivo in vitro para inducir división celular en las microsporas. Se describen los éxitos alcanzados induciendo división celular y producción de callos. No se pudo, sin embargo, regenerar plantas

The CLAVATA3/ESR Motif of CLAVATA3 Is Functionally Independent from the Nonconserved Flanking Sequences

It is believed that CLAVATA3 (CLV3) encodes a peptide ligand that interacts with the CLV1/CLV2 receptor complex to limit the number of stem cells in the shoot apical meristem of Arabidopsis thaliana; however, the exact composition of the functional CLV3 product remains a mystery. A recent study on CLV3 shows that the CLV3/ESR (CLE) motif, together with the adjacent C-terminal sequence, is sufficient to execute CLV3 function when fused behind an N-terminal sequence of ERECTA. Here we show that most of the sequences flanking the CLE motif of CLV3 can be deleted without affecting CLV3 function. Using a liquid culture assay, we demonstrate that CLV3p, a synthetic peptide corresponding to the CLE motif of CLV3, is able to restrict the size of the shoot apical meristem in clv3 seedlings but not in clv1 seedlings. In accordance with this decrease in meristem size, application of CLV3p to in vitro-grown clv3 seedlings restricts the expression of the stem cell-promoting transcription factor WUSCHEL. Thus, we propose that the CLE motif is the functional region of CLV3 and that this region acts independently of its adjacent sequences