Division of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Gyeongsang National University, Jinju, 660-701, Korea.
Planta. 2013 May;237(5):1227-39. doi: 10.1007/s00425-013-1838-8. Epub 2013 Jan 22.
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.
根毛是从表皮细胞层生长出来的，其生长受到严格的遗传调控系统和外部生长条件的调节。在水培稻田中种植的水稻植株，其所处的土壤生态与旱地植物（如拟南芥和玉米）的环境不同。为了鉴定在根毛生长中起重要作用的基因，我们采用正向遗传学方法筛选短根毛突变体。我们筛选到一个短根毛突变体，然后通过基于图谱的克隆和测序方法分离到相关基因。该突变体在剪接受体位点发生点突变，导致 OsFH1（水稻formin 同源物 1）截短。随后对另外两个 T-DNA 突变体的分析证实，OsFH1 对根毛伸长很重要。进一步的研究表明，OsFH1 对根毛生长的作用依赖于生长条件。在溶液中浸泡生长时，突变体的根毛出现缺陷，而在空气中生长时，突变体的根毛则正常。然而，突变体的根毛表型不受激素或碳水化合物的外部供应、营养物质（如 Fe 或 P i ）缺乏或通气的影响。本研究表明，OsFH1 以一种生长条件依赖的方式在根毛伸长中发挥重要作用。
