Spatio-temporal expression of PsAPY1 during germination, differentiation, and organogenesis in pea (Pisum sativum L.Var. Alaska)

Abstract

Apyrase (ATP-diphosphohydrolase, EC 3.6.1.5) catalyses the hydrolysis of nucleoside tri- and di-phosphates to nucleoside monophosphates and orthophosphates. In the present study, the spatio-temporal expression of an apyrase gene (PsAPY1) from pea (Pisum sativum L. Var. Alaska) was investigated during the early stages of germination [10 h after imbibition and 16, 35, 62, and 84 h after sowing (HAS)], using non-radioactive mRNA in situ hybridization. At 10 h after imbibition, the PsAPY1 transcript was visible in traces throughout the shoot and root tissues of the embryo. The transcript accumulation became higher by 16 HAS in the tunica layer of the shoot apical meristem, epidermis, vascular bundle, and root tip. At 35 HAS, expression signals became stronger and more widely distributed in the corpus tissues of the growing shoot apical region and in the root; the highest expression was detected in the epidermis, differentiating vascular bundle, and somewhat less in cortex tissues. By 62 HAS, the expression of PsAPY1 was strongest and extensively distributed in the above mentioned regions. At this time, higher expression was also detected in the zones of epicotyl differentiating into plumule and hook. However, at 84 HAS, the expression of PsAPY1 declined in the shoot and root, but was highly expressed in growing lateral root primordia. Germination and growth of seedlings are the physiologically most important stages in the life cycle of plants. The presence of PsAPY1 during these important stages i.e., germination, differentiation, and organogenesis indicates its essential role in growth and development of plants.