High-affinity K+Uptake in Citrus
K + is one of the most abundant mineral nutrients in plants. It fulfils important functions and its cytosolic concentration is maintained at a constant value around 100mM. This contrasts with the highly variable K + concentrations that can be found in the soil solution. Therefore, to acquire K + plant roots are furnished in K+ channels and transporters that ensure an adequate K+ nutrition under many different situations. One condition that may limit K + nutrition is salinity, a problem that affects a 30％ or irrigated land. In citrus there is little information about the mechanisms involved in K+ uptake and the negative effect of salinity. For the present study two citrus rootstocks, Carrizo and Cleopatra that differ in salt tolerance were chosen. The response of these two rootstocks to different regimens of K + nutrition and the effect of salinity on such a process were studied. Plants were germinated and grown for one month under hydroponics with nutrient solutions that contained different concentrations of K+ and Na+. After the growth period, growth parameters, mineral composition and K+ influx were determined. The effect of the K+ supply and the different levels of salinity on the development of high-affinity K+ uptake were characterized. It was observed that Carrizo grew faster than Cleopatra and showed lower tissue K + concentrations, especially at low external K +. In addition, Carrizo showed higher rates of highaffinity K+ uptake. A molecular approach was undertaken to isolate and characterize genes encoding putative high-affinity K+ transporters. By RT-PCR, several cDNA fragments were isolated that encoding transporters of the KT/HAK/KUP family. The function of these putative K+ transporters as well as the regulation of the genes encoding them in relation to plant growth and high-affinity K + uptake will be discussed.
Carrizo Cleopatra Salinity Nutrition
F. Rubio F. Caballero V. Gimeno F. Garcia V. Martinez
Departamento de Nutricion Vegetal. Centro de Edafologta y Biologla Aplkada del Segura- CSIC. Campus de Espinardo. 30100 Murcia. Spain
国际会议
11th International Citrus Congress(第11届国际柑橘大会)
武汉
英文
603-607
2008-10-01（万方平台首次上网日期，不代表论文的发表时间）