PpCKX1 localizes to vacuoles and is dominantly expressed in the stem cells. PpCKX1 regulates developmental changes with increased growth of the rhizoid and enhances dehydration and salt tolerance. Cytokinins (CKs) are plant hormones that regulate plant development as well as many physiological processes, such as cell division, leaf senescence, control of shoot/root ratio, and reproductive competence. Cytokinin oxidases/dehydrogenases (CKXs) control CK concentrations by degradation, and thereby influence plant growth and development. In the moss Physcomitrella patens, an evolutionarily early divergent plant, we identified six putative CKXs that, by phylogenetic analysis, form a monophyletic clade. We also observed that ProPpCKX1:GUS is expressed specifically in the stem cells and surrounding cells and that CKX1 localizes to vacuoles, as indicated by Pro35S:PpCKX1-smGFP. Under normal growth conditions, overexpression of PpCKX1 caused many phenotypic changes at different developmental stages, and we suspected that increased growth of the rhizoid could affect those changes. In addition, we present evidence that the PpCKX1-overexpressor plants show enhanced dehydration and salt stress tolerance. Taken together, we suggest that PpCKX1 plays regulatory roles in development and adaptation to abiotic stresses in this evolutionarily early land plant species.

中文翻译：

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细胞分裂素氧化酶 PpCKX1 在小立球菌的发育和增强脱水和耐盐性中起调节作用。

PpCKX1 定位于液泡并主要在干细胞中表达。PpCKX1 随着根状茎生长的增加调节发育变化，并增强脱水和耐盐性。细胞分裂素 (CKs) 是调节植物发育以及许多生理过程的植物激素，如细胞分裂、叶片衰老、控制茎/根比和生殖能力。细胞分裂素氧化酶/脱氢酶 (CKX) 通过降解控制 CK 浓度，从而影响植物的生长和发育。在苔藓 Physcomitrella patens 中，一种进化早期的分化植物，我们确定了六个推定的 CKX，通过系统发育分析，形成一个单系进化枝。我们还观察到 ProPpCKX1:GUS 在干细胞和周围细胞中特异性表达，CKX1 定位于液泡，如 Pro35S 所示：PpCKX1-smGFP。在正常生长条件下，PpCKX1 的过表达导致不同发育阶段的许多表型变化，我们怀疑根茎生长的增加可能会影响这些变化。此外，我们提供的证据表明 PpCKX1 过表达植物表现出增强的脱水和盐胁迫耐受性。总之，我们认为 PpCKX1 在这种进化早期的陆地植物物种的发育和适应非生物胁迫中起调节作用。我们提供的证据表明 PpCKX1 过表达植物表现出增强的脱水和盐胁迫耐受性。总之，我们认为 PpCKX1 在这种进化早期的陆地植物物种的发育和适应非生物胁迫中起调节作用。我们提供的证据表明 PpCKX1 过表达植物表现出增强的脱水和盐胁迫耐受性。总之，我们认为 PpCKX1 在这种进化早期的陆地植物物种的发育和适应非生物胁迫中起调节作用。