Overexpression of the Brassica napus BnLAS gene in Arabidopsis affects plant development and increases drought tolerance.
The GRAS proteins are a family of transcription regulators found in plants and play diverse roles in plant growth and development. To study the biological roles of GRAS family genes in Brassica napus, an Arabidopsis LAS homologous gene, BnLAS and its two homologs were cloned from B. napus and its two progenitor species, Brassica rapa and Brassica oleracea. Relatively high levels of BnLAS were observed in roots, shoot tips, lateral meristems and flower organs based on the analysis of the transcripts by quantitative RT-PCR and promoter-reporter assays. Constitutive overexpression of BnLAS in Arabidopsis resulted in inhibition of growth, and delays in leaf senescence and flowering time. A large portion of transgenic lines had darker leaf color and higher chlorophyll content than in wild type plants. Interestingly, water lose rates in transgenic leaves were reduced, and transgenic plants exhibited enhanced drought tolerance and increased recovery after exposed to dehydration treatment. The stomatal density on leaves of the transgenic plants increased significantly due to the smaller cell size. However, the stomatal aperture on the leaves of the transgenic plants reduced significantly compared with wild type plants. More epidermal wax deposition on transgenic leaves was observed. Furthermore, several genes involved in wax synthesis and regulation, including CER1, CER2, KCS1 and KCS2, were upregulated in the transgenic plants. Our results indicate a potential to utilize BnLAS in the improvement of drought tolerance in plants.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
Minggui
M
Yang
Qingyong
Q
Yang
Tingdong
T
Fu
Yongming
Y
Zhou
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029688:Brassica napus / Q000235:genetics*; D002734:Chlorophyll / Q000032:analysis; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics*; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D014170:Transformation, Genetic
D018744:DNA, Plant; D010940:Plant Proteins; D002734:Chlorophyll