Nitrate-regulated growth and cytokinin responses in seminal roots of barley.
Nitrate-regulated growth and cytokinin responses in seminal roots of barley.
复制标题
大麦种子根中硝酸盐调节的生长和细胞分裂素反应。
DOI：
10.1104/pp.98.1.309
复制
发表时间：
1992
期刊：
影响因子：
7.4
通讯作者：
C. Larsson
中科院分区：
文献类型：
--
作者：
Mariann E. Samuelson;L. Eliasson;C. Larsson
研究了硝酸盐有效性对大麦种子根生长和根细胞分裂素水平的影响。在裂根培养中，以每天0.03~0.21的相对添加速率(RA)或每天0.09的相对添加速率(RA)连续向最初N饥饿的幼苗供应硝酸盐，两个亚根的硝酸盐添加比例分别为100：0或80：20。在驯化阶段(氮素添加的前10天)和驯化阶段(氮素添加开始后10天)收集数据。全株生长限制在Ra<；每天0.15。在相同年龄段的植株中，侧根频率随着RA的增加而增加。然而，侧根频率与根的大小相关，而不是与RA相关；年龄不同但总根长相同的根也有相似的侧根频率。在驯化过程中，裂根系统中单个亚根的生长与输入到根中的总氮的比例成正比。所有亚根在驯化植株中的相对生长速率相当，它们的侧根频率与总根长的相关方式与标准培养相同。在80：20的分根培养中开始添加氮素，导致新梢和“80”根中的玉米素核苷(ZR)水平增加一倍，而“20”根的反应很小。未观察到干扰的硝酸盐有效性对ZR木质部运输的影响。“80”根在驯化过程中ZR水平较高，但驯化后恢复到“20”根的水平。驯化的标准培养物中的根细胞分裂素水平和木质部转运率在低浓度范围内不受RA影响，但在高浓度范围内增加。讨论了细胞分裂素参与硝酸盐调节的生长反应的论点。
The influence of nitrate availability on growth of seminal roots, and root cytokinin levels, was studied in barley (Hordeum vulgare L. cv Golf). Nitrate was continuously supplied to initially N-starved seedlings at relative addition rates (RA) of 0.03 to 0.21 per day (standard cultures) or at RA 0.09 per day in split root cultures with the nitrate additions distributed in ratios of 100:0 or 80:20 to the two subroots. Data were collected both during a phase of acclimation (first 10 days of N additions) and in the acclimated stage (>10 days after onset of N additions). Limitation of whole-plant growth was observed at RA <0.15 per day. The lateral root frequency increased with RA in plants of equal chronological age. However, the lateral root frequency was related to root size rather than to RA; roots of uneven age but having comparable total root lengths also had comparable lateral root frequencies. Growth of individual subroots in split root systems during acclimation was proportional to the fraction of the total N addition that was fed to the root. All subroots had comparable relative growth rates in acclimated plants, and their lateral root frequency correlated with total root length in the same manner as in standard cultures. Onset of N additions in a 80:20 split root culture resulted in doublings of zeatin riboside (ZR) levels in shoots and in the "80" root, whereas the response of the "20" root was small. No effect of perturbed nitrate availability on xylem translocation of ZR was observed. The ZR levels remained higher in the "80" root during acclimation but returned to the level of the "20" root after acclimation. Root cytokinin levels and xylem translocation in acclimated standard cultures were unaffected by RA in the lower range but increased at high RA. Arguments for involvement of cytokinins in the nitrate-regulated growth response are discussed.