Os04g0536300

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TOB1 encodes a YABBY protein, which is closely related to FILAMENTOUS FLOWER in Arabidopsis thaliana.

Annotated Information

Function

  • TOB1 encodes a YABBY protein, which is closely related to FILAMENTOUS FLOWER in Arabidopsis thaliana, and is expressed in the lateral organ primordia without any patterns of polarization.
  • TOB1 is responsible for the initiation and growth of the lemma and palea, and acts non-cell autonomously to maintain the activity and proper organization of the meristem. TOB1 is therefore likely to play an important role in rice spikelet development.

Mutation

Figure 1. Phenotypes of Spikelets in the tob1 Mutant. [1].


  • mutation of the rice (Oryza sativa) gene TONGARIBOUSHI1 (TOB1) results in pleiotropic phenotypes in spikelets, such as the formation of a cone-shaped organ instead of the lemma or palea, the development of two florets in a spikelet, or premature termination of the floret meristem, in addition to reduced growth of the lemma or palea and elongation of the awn. These phenotypes seem to result from not only failure in growth of the lateral organs, but also defects in maintenance and organization of the meristem.







Expression

Figure 5. Temporal and Spatial Expression Pattern of TOB1 during Flower and Leaf Development. [1].
  • First, the researchers examined the organ-specific expression patterns of TOB1 by RT-PCR. TOB1 expression was detected in the vegetative shoot apex, including leaf primordia, and young inflorescences, including developing spikelets (see Supplemental Figure 3 online). By contrast, no expression was detected in fully differentiated leaves and roots.
  • Next, the researchers analyzed the temporal and spatial expression pattern of TOB1 in developing spikelets by in situ hybridization. TOB1 was strongly expressed in the primordia of all lateral organs in the spikelet from their initiation stages (Figure 5A). Its expression was detected throughout the primordia: No abaxially or adaxially localized signal was detected (Figures 5B and 5D). The TOB1 signal appeared to be localized to the upper region of the primordia of sterile lemma and rudimentary glume, whereas it was uniformly detected in the lemma and palea primordia (Figures 5B and 5C). In the stamen, in particular, TOB1 signal was restricted to the narrow region of the apical part of the anther primordia (Figure 5C). Notably, no expression was detected in the floret meristem (Figure 5B), raising the possibility that the meristem defect in tob1 was caused by a non-cell-autonomous action of TOB1.
  • In the vegetative phase, TOB1 was expressed in the apical and peripheral region of the leaf primordia, and no expression was observed in the SAM, as found above for the floret meristem (Figures 5E and 5F).







Evolution

Figure 4. Phylogenetic tree of the YABBY proteins. The tree was constructed on the basis of the zinc-finger and YABBY domains by a neighbor-joining method. Numbers above branches indicate the percentage of bootstrap values calculated from 1000 replicates. [1].
  • Rice has eight YABBY genes in the genome. The researchers constructed a phylogenetic tree of the YABBY genes including well-characterized members in Arabidopsis, A. majus, and maize (Figure 4).

Labs working on this gene

  • Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
  • National Institute of Agrobiological Sciences, Kannondai, Tsukuba 305-8602, Japan
  • Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8562, Japan

References

  1. 1.0 1.1 1.2 Cite error: Invalid <ref> tag; no text was provided for refs named ref1

Structured Information