AUTHOR=Zhu Shengnan , Chen Minhui , Liang Cuiyue , Xue Yingbin , Lin Shuling , Tian Jiang 

TITLE=Characterization of Purple Acid Phosphatase Family and Functional Analysis of GmPAP7a/7b Involved in Extracellular ATP Utilization in Soybean

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00661

DOI=10.3389/fpls.2020.00661

ISSN=1664-462X

ABSTRACT=<p>Low phosphate (Pi) availability limits crop growth and yield in acid soils. Although root-associated acid phosphatases (APases) play an important role in extracellular organic phosphorus (P) utilization, they remain poorly studied in soybean (<italic>Glycine max</italic>), an important legume crop. In this study, dynamic changes in intracellular (leaf and root) and root-associated APase activities were investigated under both Pi-sufficient and Pi-deficient conditions. Moreover, genome-wide identification of members of the <italic>purple acid phosphatase</italic> (<italic>PAP</italic>) family and their expression patterns in response to Pi starvation were analyzed in soybean. The functions of both <italic>GmPAP7a</italic> and <italic>GmPAP7b</italic>, whose expression is up regulated by Pi starvation, were subsequently characterized. Phosphate starvation resulted in significant increases in intracellular APase activities in the leaves after 4 days, and in root intracellular and associated APase activities after 1 day, but constant increases were observed only for root intracellular and associated APase activities during day 5–16 of P deficiency in soybean. Moreover, a total of 38 <italic>GmPAP</italic> members were identified in the soybean genome. The transcripts of 19 <italic>GmPAP</italic> members in the leaves and 17 in the roots were upregulated at 16 days of P deficiency despite the lack of a response for any <italic>GmPAP</italic> members to Pi starvation at 2 days. Pi starvation upregulated <italic>GmPAP7a</italic> and <italic>GmPAP7b</italic>, and they were subsequently selected for further analysis. Both GmPAP7a and GmPAP7b exhibited relatively high activities against adenosine triphosphate (ATP) <italic>in vitro</italic>. Furthermore, overexpressing <italic>GmPAP7a</italic> and <italic>GmPAP7b</italic> in soybean hairy roots significantly increased root-associated APase activities and thus facilitated extracellular ATP utilization. Taken together, these results suggest that GmPAP7a and GmPAP7b might contribute to root-associated APase activities, thus having a function in extracellular ATP utilization in soybean.</p>