2013 Annual Report
2: To positionally clone genes that regulate plant architecture in maize. [NP 301, C4, PS 4A]
3: To determine the function of genes through transgenic tests. [NP 301, C4, PS 4A]
Objective 1. We identified a new maize mutation that has pleiotropic developmental defects. The internodes do not expand regularly, leading to a bunching of leaves and a short stature. The ear tips are fasciated and the plants are sterile. This mutation has been mapped to the bottom of chromosome 1. A mapping population has generated roughly 200 mutants that are being scored with markers for recombination events. We have also created mapping populations for a mutation with upright tassel branches and a dominant Tasselseed mutation.
Objective 2. During the course of the 5 years, we cloned a number of genes, most recently, we cloned liguleless narrow. Liguleless narrow was shown to encode a kinase. The paralog gene, sister of liguleless narrow (sln), is expressed at very low levels except in the dominant Lgn-R mutant. One hypothesis is that sln levels increase to compensate for the loss of lgn function. We identified insertions in the sln gene that will help us determine its role in the dominant Lgn-R mutant.
Objective 3. We showed that Wavy auricle in blade (Wab1) encodes a TCP transcription factor. This TCP gene is misexpressed in leaves of dominant Wab1-R mutants. We determined that liguleless1 is increased in Wab1-R mutants. We obtained an antibody to LG1 and showed that it is expressed in the preligule band in normal plants. In Wab1-R plants, the LG1 expression expands up into the blade as well as appears earlier in development than in non-mutant siblings. Wab is normally not expressed in leaves, but is expressed in tassels by RNAseq data. Using the LG1 antibody, we found that LG1 is expressed in the axils of tassel branches and that LG1 expression disappears in wab-ref loss of function alleles. Our hypothesis is that WAB is normally expressed in tassels and regulates LG1. In the gain of function mutant, it misexpresses LG1, leading to the dramatic leaf phenotypes. In the wab-ref loss of function allele, lg1 expression disappears and the tassel branches are fewer and more upright.
Moon, J., Candela, H., Hake, S.C. 2013. The Liguleless narrow mutation affects proximal distal signaling and leaf growth. Development. 140(2):405-412.