Formin homology 1 (OsFH1) regulates root-hair elongation in rice (Oryza sativa)
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The outgrowth of root hairs from the epidermal cell layer is regulated by a strict genetic regulatory system and external growth conditions. Rice plants cultivated in water-logged paddy land are exposed to a soil ecology that differs from the environment surrounding upland plants, such as Arabidopsis and maize. To identify genes that play important roles in root-hair growth, a forward genetics approach was used to screen for short-root-hair mutants. A short-root-hair mutant was identified, and the gene was isolated using map-based cloning and sequencing. The mutant harbored a point mutation at a splicing acceptor site, which led to truncation of OsFH1 (rice formin homology 1). Subsequent analysis of two additional T-DNA mutants verified that OsFH1 is important for root-hair elongation. Further studies revealed that the action of OsFH1 on root-hair growth is dependent on growth conditions. The mutant Osfh1 exhibited root-hair defects when roots were grown submerged in solution, and mutant roots produced normal root hairs in the air. However, root-hair phenotypes of mutants were not influenced by the external supply of hormones or carbohydrates, a deficiency of nutrients, such as Fe or P i , or aeration. This study shows that OsFH1 plays a significant role in root-hair elongation in a growth condition-dependent manner.
KeywordsMap-based cloning Root hair Formin homology 1 Tip elongation Submergence
BUD NECK INVOLVED PROTEIN
Cryo-scanning electron microscope
Formin homology 1
P1-based artificial chromosome
Quantitative reverse transcriptase PCR
Synthetic green fluorescent protein
This work was supported by grants from the Next-Generation BioGreen 21 Program (PJ008215 and PJ008168), the Rural Development Administration, Republic of Korea. Jingmiao Liu is supported by a scholarship from the BK21 program. This research was also supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2011-0009096). We are grateful to Dr. Liam Dolan (University of Oxford, UK) for helping us with cryo-SEM work.
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