Subbaiah C C, Zhang J, Sachs M M
Department of Agronomy, University of Illinois, USA.
Plant Physiol. 1994 May;105(1):369-76. doi: 10.1104/pp.105.1.369.
Ca-mediated processes are known to be involved in transducing many developmental, hormonal, and environmental cues in plant cells. In this study, the role of Ca in the perception of anoxic stress signals by maize (Zea mays L. cv B73) roots was assessed by studying the effect of various Ca antagonists on the induction of alcohol dehydrogenase (ADH) and sucrose synthase mRNA as well as ADH activity under anoxia. The effect of these compounds on the poststress recovery of the seedlings was also monitored. Ruthenium red (RR), an inhibitor of organellar Ca fluxes, repressed the anoxic activation of the alcohol dehydrogenase1 and shrunken1 genes as measured by their transcript levels as well as ADH activity. Furthermore, RR-treated seedlings could not recover even after only 2 h of flooding, in contrast to untreated B73 seedlings that survived 72 h of submergence. Ca, when supplied along with RR, allowed normal anoxic gene expression and also prevented the RR-imposed death of the seedlings from short-term anoxia. Ca (45Ca) fluxes were measured in maize roots to elucidate the mode of action of RR. RR abolished anoxia-stimulated 45Ca influx into maize roots but did not affect aerobic Ca2+ uptake, unlike a few other antagonists that blocked both the aerobic and anoxic fluxes. However, Ca uptake across the plasma membrane was not necessary for the adaptive response to anoxia, since chelation of extracellular Ca by ethyleneglycol-bis(beta-aminoethyl ether)-N,N'-tetraacetic acid or 1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid did not affect the induction of ADH activity or poststress survival of flooded seedlings. The data suggest that RR may act on one of the intracellular stores of Ca and the Ca mobilized from this source is a physiological transducer of anoxic stress signals in maize roots.
已知钙介导的过程参与植物细胞中许多发育、激素和环境信号的转导。在本研究中，通过研究各种钙拮抗剂对缺氧条件下玉米（Zea mays L. cv B73）根中乙醇脱氢酶（ADH）和蔗糖合酶mRNA的诱导以及ADH活性的影响，评估了钙在玉米根感知缺氧应激信号中的作用。还监测了这些化合物对幼苗应激后恢复的影响。钌红（RR）是一种细胞器钙通量抑制剂，通过其转录水平和ADH活性测定，它抑制了乙醇脱氢酶1和收缩蛋白1基因的缺氧激活。此外，与未经处理的能在72小时淹水后存活的B73幼苗相比，经RR处理的幼苗即使在仅2小时淹水后也无法恢复。当与RR一起供应钙时，可使缺氧基因正常表达，并防止RR导致的幼苗因短期缺氧而死亡。在玉米根中测量了钙（45Ca）通量，以阐明RR的作用模式。RR消除了缺氧刺激的45Ca流入玉米根，但不影响有氧条件下的钙吸收，这与其他一些同时阻断有氧和缺氧通量的拮抗剂不同。然而，如果将细胞外钙螯合，通过乙二醇双（β-氨基乙醚）-N，N'-四乙酸或1，2-双（2-氨基苯氧基）乙烷N，N，N'，N'-四乙酸对缺氧的适应性反应并无影响，因为这两种螯合剂并不影响ADH活性的诱导或淹水幼苗应激后的存活。数据表明，RR可能作用于钙的一种细胞内储存库，从该来源动员的钙是玉米根中缺氧应激信号的生理转导物。
