Study On Function Of High-affinity Potassium Transporter Gene PaHAK1of Phytolacca Acinosa Roxb

Potassium (K+) is one of indispensable nutrients required for growth and development. It is generally accepted that plant often absorb K+completely together by low-affinity K+transporter and high-affinity K+transporter in root plasma membrane. Phytolacca acinosa Roxb is a kind of high potassium content plant which could normally grow and develop at low K+condition, and it may be related to the higher expression of high-affinity K+transporter. To study the function of gene PaHAK1of Phytolacca acinosa Roxb and screen the transgenic rice strains with efficient potassium absorption, model plant Arabidopsis was transferred via Agrobacterium-mediated floral-dip transformation to study the function of gene PaHAKl and transgenic PaHAKl rice strains were obtained to study the molecular identification and phenotypic analysis in this study. Moreover, the transgenic PaHAKl rice strains were analyzed on parameters of potassium absorption kinetics under different potassium concentration treatments and screened the transgenic rice strains with high K+uptake ability by solution culture. The results are as follows:1The over-expression vector pWM101-PaHAK1was constructed successfully, which was transferred into Arabidopsis mutants hak5and aktl via Agrobacterium-mediated floral-dip transformation. Transgenic Arabidopsis strains were obtained by PCR.2The RNA of transgenic Arabidopsis and transgenic rice of leaves tissue were extracted respectively, which showed that gene PaHAKl was expressed both in Arabidopsis and rice by RT-PCR.3The phenotypic analysis showed that transgenic PaHAK1Arabidopsis were expressed long petioles, larger leaves and delayed flowering.4Functional recovery study of Arabidopsis mutants hak5and aktl showed that the growth of transgenic PaHAK1Arabidopsis could recovered after low potassium concentration treatments, it suggested that PaHAKl be high-affinity K+transporter involved in K+uptake and transport under low K+condition.5The phenotypic analysis was showed that the growth of transgenic PaHAKl rice was better than rice under low K+condition, while little difference between them under high K+condition. It suggested gene PaHAKl be high-affinity K+transporter and express under low K+condition.6The study on parameters of potassium absorption kinetics suggested that all of the transgenic PaHAKl rice strains had lower Km and lower Cmin under low K+condition, and most of them had lower Km and lower Cmin under high K+condition. However, the fourth transgenic rice strain had lower Km, lower Cmin and higher Imax under high or low K+condition, which was fitted to grow in a wide range of potassium nutrition conditions. Therefore the fourth transgenic rice strain had high K+uptake ability with efficient potassium absorption.