Molecular Characterization of Phosphorous Starvation Tolerance 1 Gene in Wheat

Abstract

Phosphorus is an important macroelement that regulates crop health, grain yield, and productivity. Increasing demand for phosphorus fertilizer, unfertile soils, limited resources of poor farmers, and depleting reservoirs of natural phosphorus are among the major problems of phosphorus deficiency. Wheat crop is mostly grown on marginal lands and rainfed areas, where phosphorus content is lower, and P fixation is limited. The development of wheat varieties with a deep rooting system, nutrient-use efficiency, and high yielding under phosphorus starvation condition is the sole solution to improving wheat productivity. To develop such wheat varieties, it is necessary to identify the genetic regulators involved in the P use efficiency and deeper rooting. The Phosphorus Starvation Tolerance 1 (PSTOL1) gene has been identified and characterized in rice, maize, and sorghum. This gene is suggested to play a key role in efficient P uptake, deeper rooting, and high yield production under phosphorus starvation. Previous studies in wheat only focused on one homolog, TaPstol5AS-1, and characterized its role in phosphorus-use-efficiency. Therefore, the present study was carried out to characterize the TaPSTOL1 gene at a genome-wide level. We identified the 22 orthologs in the whole wheat genome using the latest reference sequence (IWGSC v.1.1). Based on the phylogenetic tree, these orthologs of the PSTOL1 gene were classified into three groups. Using RNA-sequence data from a previous study, the expression profiling of 22 orthologs was analyzed in root and shoot tissues under normal and phosphorus-deficient conditions. Four putative candidate genes (TraesCS3A02G018500.1, TraesCS3B02G295000, TraesCS5B02G391900, TraesCS5D02G396800) were selected based on differential expression in shoot and root under control and P starvation condition. RT-PCR further verified the expression pattern of these genes. P-efficient (Pakistan-13) wheat cultivar also significantly increased P-uptake, root length, volume, and surface area compared to P-non-efficient (Shafaq-06) cultivar. Altogether, these results revealed the role of the PSTOL1 gene in wheat P-uptake, root architecture, and efficient growth of plants under phosphorus starvation conditions. In the future, functional validation of the putative candidate genes in wheat will help us identify the role of the TaPSTOL1 gene.