Nina V. Evseeva1*, Olga A. Demchenko1, Sergei Yu. Shchyogolev1 and Alexander D. Volodarsky2
1Institute of Biochemistry and Physiology of Plants
and Microorganisms, Russian Academy of Sciences (IBPPM RAS), 13 Entuziastov
Ave., Saratov 410049, Russia
2lnstitute of Plant Physiology, Russian Academy of Sciences, 35 Ulitsa
Botanicheskaya, Moscow 127276, Russia
Summary
The content of the proliferative antigen of initial cells (PAI) in the stem apex cells of two common wheat (Trittcum aestivum L.) cultsvars differing considerably in their drought resistance - Saratovskaya 29 and Opal - was measured at post-osmotic stress repair by using a special immunochemical test system. The PAI content of these cells was studied as normal and at post-stress repair. A marked response of droughted plants was obtained that was reflected by a change in the PAI content of stem apical cells. Saratovskaya 29 (resistant) did not differ from Opal (sensitive) in the post-stress resumption of leaf growth processes. However, differences in the content of PAI were observed during the post-stress regeneration of the meristematic tissues. These differences can serve as a basis for the study and prediction of plant resistance to unfavorable abiotic factors in the breeding of high-yielding wheat cultivars.
Introduction
Plant apical meristems are universal biological systems where the morphogenetic potential of stem cells (initial cells, or initials) is realized. Tiohe nature and function of these cells are poorly known, as are the molecular mechanisms of cooperative interactions among stem apex meristematic cells at stress. An in-depth analysis of such interactions requires that the functional activity of stressed cells be investigated on the molecular-cellular level.
The shift to research on the molecular-cellular level is feasible in principle if suitable molecular markers are available that are associated with cell division and reflect the functional activity of dividing cells. Such molecules have been studied both in vitro in cultures of synchronously dividing cells (Smith et al. 1988; Kodama et al. 1991; Kiyosue et al. 1991; Magyar et al. 1997; Meszaros et a). 2000) and in vivo in the cells of higher plant life (John et al. 1989; Hush et al. 1996; Schuppler et al. 1998; Mironov et al. 1999; Beemster et al. 2002). These investigations have been primarily to document the peculiarities of genetic system functions that control the proliferation and further differentiation of plant cells.
Previously, we and others (Volodarsky 1985; Moiseeva 1991; Sumaroka et al. 2000) showed that the apical meristem of the wheat stem contains a specific antigen (proliferative antigen of initials, PAI) that is characteristic of actively proliferating cells. The celluar PAl level in the rye stem apex is correlated with whole-plant growth (Volodarsky et al. 1986) and is associated with the embryogenic capacity of the wheat callus tissue in an in vitro culture (Evseeva et al. 2002). Those studies suggested that the PAl content of plant meristems will also permit one to assess stress-induced changes in meristem cell proliferative activity.
The aim of this work was to study osmotic-stress-induced changes in the content of PAI in the stem apices of two wheat cultivars differing in stress resistance.