关键词: 小麦（Triticum aestivum L.） , 磷转运蛋白基因 , 磷素供应 , 磷素吸收利用 , 干物质生产

Abstract: 【Objective】 In this study, the chromosome localization of TaPHT2;1, a phosphate transporter gene in wheat, was determined by using Chinese spring (CS) and its chromosome-based ditelosimic lines of B genome. Moreover, the expression pattern of TaPHT2;1 as well as its relationship with plant dry matter production and P use efficiency was studied under high- and low-Pi conditions.【Method】The cultivar CS together with its chromosome-based ditelosimic lines of B genome as well as wheat cultivars with varied P use efficiencies was hydroponically cultured. The chromosomal localization of TaPHT2;1 was detected by PCR amplification using specific primers with genome DNA of the tested materials as the template. The expression patterns of TaPHT2;1 in CS, its chromosome-based ditelosimic lines of B genome, and wheat cultivars with different P use efficiencies were determined by semi-quantitative RT-PCR and real time PCR. The plant dry weight and P acquisition parameters of the tested materials were assayed by following the conventional approach. 【Result】 For the CS and its chromosome-based ditelosimic lines of B genome, only 1BS that a line lacking the long arm of 1B was failed to detect the transcripts of TaPHT2;1, indicating that TaPHT2;1 is located in the long arm of 1B. Under P sufficience and P deprivation, the expression of TaPHT2;1 in roots and leaves of CS and other ditelosimic lines of B genome other than 1BS exhibited to be predominant in leaves and the expression levels were induced by Pi deprivation stress. The expression of TaPHT2;1 in roots was not regulated by Pi deprivation stress. These results suggest that TaPHT2;1 is involved in mediating plant Pi acquisition and cellular Pi translocation under Pi sufficience and in regulating re-transportation of cellular Pi under Pi deprivation. Under P sufficience, the plant dry weight and total Pi content in 1BS were significantly decreased in comparison with those in CS; under Pi deprivation, the plant dry weight of 1BS was also significantly lower than that of CS, but 1BS had higher total Pi content than CS. Therefore, the phosphate transporter gene TaPHT2;1 that located on the long arm of 1 B exerts dramatic effects on plant dry mass production under various Pi-supply conditions through its regulation of plant P acquisition and cellular Pi translocation. Under Pi sufficience, the accumulative Pi amount per plant of 1BS was significantly increased compared with that of CS, but there were no variations in Pi use efficiency between them. Under Pi deprivation, the Pi use efficiency of 1BS was significantly decreased compared with that of CS, but there were no variations in accumulative Pi amount per plant between them. In addition, under Pi sufficience, the expression level of TaPHT2;1, plant dry weight, total Pi content, and accumulative Pi amount per plant were all increased along with the increase of Pi use efficiencies across the tested wheat cultivars that displayed varied Pi use utilization properties. Under Pi deprivation, the expression level, plant dry weight, and Pi use efficiency were also increased along with the increase of the Pi use efficiencies in the tested wheat cultivars. However, the total Pi content exhibited a decrease tendency and the accumulative Pi amount per plant showed little variation among the wheat cultivars. Taken together, these results clearly indicate that there is a close association between the expression level of TaPHT2;1 and plant Pi acquisition, Pi utilization, and dry matter production in wheat cultivars with varied Pi use efficiencies under the conditions of Pi sufficience and Pi deprivation.【Conclusion】The wheat phosphate transporter gene TaPHT2;1 is located on the long arm of 1B. TaPHT2;1 plays an important role in regulation of plant dry mass production through its distinct response to external Pi conditions, which further modifies to most extent the plant Pi acquisition and utilization. This study confirms that TaPHT2;1 is a critical component in regulating plant Pi acquisition under Pi sufficience and Pi utilization under Pi deprivation. It can act as a molecular reference in evaluating Pi use efficiencies in wheat.

Key words: wheat (Triticum aestivum L.) , phosphate transporter gene , Pi supply , phosphate acquisition and utilization , dry mass production