Os08g0131100

The rice Os08g0131100 was reported as CYP703A3 (genomes uncoupled 4) in 2014 by researchers from China.

Annotated Information

Gene Symbol

• Os08g0131100 <=> CYP703A3,OsCYP703A3

Figure 1. Phenotypic comparison between the wild type and cyp703a3‐2..

Function

• The Oryza sativa mutant cyp703a3-2 caused by one base insertion in CYP703A3 displays defective pollen exine and anther epicuticular layer, which differs from Arabidopsis cyp703a2 in which only defective pollen exine occurs.
• CYP703A3 represents a conserved and diversified biochemical pathway for in-chain hydroxylation of lauric acid required for the development of male organ in higher plants.

Figure 2. Transverse section analysis of the anther development in the wild type and cyp703a3‐2..

Phenotypic analysis

• Even though cyp703a3‐2 has normal vegetative development, and inflorescence and floral morphology (Figure 1A–D), its anthers appeared pale yellow and smaller without mature pollen grains compared with the wild type (Figure 1E–I).
• There were no detectable differences during the early stages of the anther development between the cyp703a3-2 and wild-type plants. Until stage 9 of anther development, the cyp703a3-2 mutant could undergo normal meiosis and released normal young microspores similar to the wild type (Figure 2A, B, F and G).
• At stage 10, wild‐type microspores became round and vacuolated with thick surrounding exine, and the tapetum layer was thin because of tapetal degradation (Figure 2C), while cyp703a3-2 micro- spores had thin and weakly stained exine, indicating abnormal sporopollinin deposition (Figure 2H).
• At stage 11, the uninucleate microspore of wild‐type plants underwent the first mitotic division, generating binucleate pollen grains (Figure 2D) (Zhang and Wilson 2009). However, at this stage, cyp703a3‐2 microspores developed irregular and disintegrating appearance, becoming aggregated at one side of the anther locule (Figure 2I).
• At stage 13, the wild‐type anther locule was full of mature pollen grains, by contrast, the mutant anther locule was empty and flat (Figure 2E and J).

Expression

• Chromatin immunoprecipitation and expression analyses revealed that the expression of CYP703A3 is directly regulated by Tapetum Degeneration Retardation, a known regulator of tapetum PCD and pollen exine formation.

Labs working on this gene

• State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
• Institute of Plant Molecular Biology, National Center for Scientific Research, University of Strasbourg, 67083, Strasbourg Cedex, France.