Analysis Of Potassium Nutrition Characteristic And Cloning The High-affinity Potassium Transporter Gene Of Celosia Argentea L.

Celosia argentea L. is an amaranthaceae annual herb. And it is also a typical K-rich plant. More about genes of high affinity potassium transporters has been known with the development of molecular biology. But those reseaarch mainly focus on some model plants such as arabidopsis, rice, barley and other crops. In this study, in order to meet the need of potassium nutrition characteristic improvement for crop and use of potassium nutrition related gene. Celosia argentea as the material has been investigated about its k nutrition characteristics, and a high affinity potassium transporter gene has been cloned. And also CaHAKl gene expression and sequence have been analyzed. The main research results were as follows:1. Under the different potassium level, with K+ concentration increasing, the Km value of Celosia argentea was also increasing. And under K+ concentration higher than 0.20 mmol/L, its value has risen sharply. Probably in this concentration the K+absorption mechanism of Celosia argentea has been changed. Under low potassium condition, the affinity of K+ was greater than other plant, indicated that Celosia argentea was a high affinity potassium plant. Meanwhile under low potassium condition, the root/shoot ratio of Celosia argentea was higher than the ratio under high potassium condition, this showed that its root activity was strong in low potassium condition. The chlorophyll content of Celosia argentea did not change significantly in different K+ concentration. But the K+ concentration of solution would influence the photosynthesis when concentration was too low or too high.2. Under the normal potassium condition, the content of potassium in stem was higher than root and leaf. And the contents were 50 mg/g above. Potassium supply directly affects distribution of potassium in plants.3. A HAK gene from Celosia argentea has been cloned using RT-PCR and RACE. Its cDNA consisted 2498 bp and could encode 777 amino acids. This gene was submitted to GenBank with an accession number JF719837, and was designated as CaHAKl. 4. Real-Time PCR showed that the CaHAK1 was detected in all tissue of Celosia argentea, but it was main expressed in roots. And under lower potassium concentration the relative expression of CaHAKl was higher than the relative expression under normal potassium concentration. These showed that CaHAKl could be induced expression under lower potassium concentration.5. For homology analysis, the results indicated that the nucleotides sequence of CaHAK1 has high similarity with other HAK genes. And the homology of amino acid sequence was high identity with other plants such as Mesembryanthemum crystallinum with 87%, Phytolacca acinosa with 86%, Gossypium hirsutum with 79%. Molecular weight of putative CaHAK1 protein is 87.5518 kD, and isoelectric pI is 7.89. By function conservative domain and phylogenetic analysis, CaHAKl has high conservation and closely relationship with other HAK genes, the results indicated that the CaHAKl gene was the high affinity potassium transporter gene of Celosia argentea.