Os04g0509300

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Annotated Information

Function

• Biochemical and genetic analyses indicate that Os DCL4 is the major Dicer responsible for the 21-nucleotide siRNAs associated with inverted repeat transgenes and for trans-acting siRNA (ta-siRNA) from the endogenous TRANS-ACTING siRNA3 (TAS3) gene.

Mutation

• To determine the role of Os DCL4 encoded by Os 04g43050 in small RNA biogenesis and rice development, 15 individual transgenic plants expressing an inverted repeat of Os DCL4 (DCL4IR) were generated. During reproductive development, the basic branching architecture of the panicle in DCL4IR transformants was normal except for the absence of certain spikelets in the lower part of the rachis (Figures 1A and 1B). Compared with wild-type plants (Figure 1C), spikelet organ identity was greatly disrupted in the DCL4IR transformants (Figures 1D to 1F). Three typical phenotypes from weak to strong were observed, including a slight opening between the lemma and the palea (Figure 1D) and the lemma being partially or completely degenerated to the awn (Figures 1E and 1F). Moreover, the empty glumes and the rudimentary glumes were separated in DCL4IR transformants (Figures 1D to 1F) instead of being close together, as in the wild-type control (Figure 1C). As a result, the strong loss-of-function transgenic plants (Figure 1F) were sterile and only two weak loss-of-function plants could produce seeds for further genetic analysis (Figure 1D). The offspring from the weak loss-of-function plants (Figure 1D) showed the expected 1:3 segregation of normal to abnormal phenotype. When 41 T1 plants from two individual transgenic lines were examined, the abnormal phenotype cosegregated with the DCL4IR transgenes (Figure 1G).

Figure 1. Knockdown of Os DCL4 Causes Abnormal Morphology in Rice. (A) An inflorescence of wild-type Nipponbare rice. (B) An inflorescence of DCL4IR transgenic rice. (C) A spikelet of wild-type rice. The palea (p), lemma (l), a pair of empty glumes (eg), and a pair of rudimentary glumes (rg) are indicated. (D) to (F) The spikelets of DCL4IR transformants showing weak (D), intermediate (E), and strong (F) phenotypes. Asterisks represent the space between the empty glume and the rudimentary glume; carets indicate the impaired lemma. (G) Small RNA gel blot analysis of DCL4IR siRNA levels (indicated at right) in wild-type and DCL4IR transgenic progeny (WTF and AF, respectively). Line 1 and line 2 are two independent T1 generation lines of DCL4IR transformants. AF, transgenic plants displaying abnormal flowering; WTF, wild-type phenotypic progeny. 5S/tRNA stained with ethidium bromide was used as a control. .

Expression

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Evolution

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Labs working on this gene

• State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental

Biology, Chinese Academy of Sciences, Beijing 100101, China

• Graduate University of the Chinese Academy of Sciences, Beijing 100039, China
• Laboratory of Molecular and Developmental Biology and National Center for Plant Gene Research, Institute of Genetics and

Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China

• National Institute of Biological Science, Beijing 102206, China
• Department of Molecular, Cellular, and Development Biology, Yale University, New Haven, Connecticut 06520-8104