Os03g0650400

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Annotated Information

Function

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Mutation

• The mutant plant was normal in vegetative development, although no pollen was produced (Figure 1A and 1B). Normal phenotype plants and sterile plants from the progeny of Osam1 +/− give 3:1 segregation, establishing it as a single recessive mutant (χ2 = 0.83; P > 0.05). The researchers named the mutant Osam1-1. When pollinated with normal pollen from wild-type plants, Osam1-1 plants do not set seeds.

Figure 1 Comparison of the wild-type and Osam1-1 mutant phenotype. (A) A wild-type plant (left) and an Osam1-1 mutant plant (right). (B) A wild-type panicle (left) and an Osam1-1 mutant panicle (right). .

• To determine the anther morphological defects in Osam1- 1, transverse sections of both wild-type and mutant anthers at different developmental stages were examined. The development of rice anthers has been described in detail. Before entering meiosis, the four-layered anther wall, including epidermis, endothecium, middle layer and tapetum, is formed and primary sporogenous cells develop into larger PMCs in the anther locules (Figure 2A). The PMCs gradually become spherical and enter meiosis (Figure 2B and 2C). At the end of meiosis, the PMCs develop into tetrads. Concomitantly, the middle layer and tapetum begin to degenerate. After going through the vacuolated stage (Figure 2D) and two rounds of mitosis (Figure 2E), microspores then generate the mature tricellular pollen grains (Figure 2F). There was no detectable difference between Osam1-1 and wild-type anthers before entering meiosis, and the four layers of anther wall were also normal (Figure 2G). The impairment of anther development was observed in Osam1-1 after PMCs enlarged and entered meiosis (Figure 2H). The tapetal cells had significantly swelled and the PMCs did not complete meiosis (Figure 2I). The development of PMCs in Osam1-1 anthers seemed to be interrupted; they were arrested at the PMC stage with aberrant tapetum development (Figure 2J and 2K). Eventually, all the PMCs as well as tapetum had disappeared, leading to the anthers without pollen (Figure 2L).

Figure 2 Transverse sections of anthers in both wild type and the Osam1-1 mutant. As the development of the Osam1-1 PMCs was arrested, the sections of Osam1-1 anthers were selected according to the length of spikelet. The wild-type sections are shown in A-F, and the Osam1-1 sections are shown in G-L. (A, B, G, H) Early meiosis stage. (C, I) Late meiosis stage. (D, J) Vacuolated pollen stage. (E, K) Pollen mitosis stage. (F, L) Mature pollen stage. E, epidermis; En, endothecium; ML, middle layer; T, tapetum; PMCs, pollen mother cells; MP, mature pollen. Scale bars, 5 μm. .

Expression

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Evolution

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Labs working on this gene

• State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
• Key Laboratory of Plant Functional Genomics of Ministry of Education, Yangzhou University, Yangzhou 225009, China