PROLIFERATION OF MAIZE (ZEA-MAYS-L) ROOTS IN RESPONSE TO LOCALIZED SUPPLY OF NITRATE
PROLIFERATION OF MAIZE (ZEA-MAYS-L) ROOTS IN RESPONSE TO LOCALIZED SUPPLY OF NITRATE
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DOI：
10.1093/jxb/40.2.263
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发表时间：
1989-02-01
影响因子：
6.9
通讯作者：
RAPER, CD
中科院分区：
文献类型：
--
作者：
GRANATO, TC;RAPER, CD
玉米（Zea mays L.）具有两个初级节根轴的植株在流动营养培养中生长8d，每个轴独立地供应NO3-。干物质积累的根是相似的，无论1.0摩尔m-3 NO3-供应到一个或两个轴。然而，当NO3-只供应给一个轴时，在供应NO3-的轴中，根系内干物质的积累显著更大。干物质积累的增加+N处理轴是完全归因于增加的密度和侧枝的生长，而不是主轴的生长差异。+N轴侧枝的增殖与原位还原和利用一部分吸收的NO3-的能力有关，特别是在侧原基起始的顶端区域。尽管还原态氮被转移到-N轴，但-N轴的浓度仍显著低于+N轴。 还原态氮的浓度，以及在体外NO3-还原酶活性，是在顶端比在+N轴的更多的基础区域。在+N轴侧支的增殖增强伴随着轴的总呼吸速率的增加。呼吸作用的增加部分是由于根系质量的增加。比呼吸速率（mmol CO2每小时每克根干重）也大于+N比-N轴。如果呼吸速率被视为代表的库需求，刺激启动和增长的arabia原位利用本地外源供应的NO3-建立了一个增加的库需求，通过增强代谢活动和增加分配同化物+N轴之间的差异，在+N和-N轴的库需求。
Maize (Zea mays L.) plants with two primary nodal root axes were grown for 8 d in flowing nutrient culture with each axis independently supplied with NO3-. Dry matter accumulation by roots was similar whether 1.0 mol m-3 NO3- was supplied to one or both axes. When NO3- was supplied to only one axis, however, accumulation of dry matter within the root system was significantly greater in the axis supplied with NO3-. The increased dry matter accumulation by the +N-treated axis was attributable entirely to increased density and growth of lateral branches and not to a difference in growth of the primary axis. Proliferation of lateral branches for the +N axis was associated with the capacity for in situ reduction and utilization of a portion of the absorbed NO3-, especially in the apical region where lateral primordia are initiated. Although reduced nitrogen was translocated to the -N axis, concentrations in the -N axis remained significantly lower than in the +N axis. The concentration of reduced nitrogen, as well as in vitro NO3- reductase activity, was greater in apical than in more basal regions of the +N axis. The enhanced proliferation of lateral branches in the +N axis was accompanied by an increase in total respiration rate of the axis. Part of the increased respiration was attributable to increased mass of roots. The specific respiration rate (mmol CO2 evolved per hour per gram root dry weight) was also greater for the +N than for the -N axis. If respiration rate is taken as representative of sink demand, stimulation initiation and growth of laterals by in situ utilization of a localized exogenous supply of NO3- established an increased sink demand through enhanced metabolic activity and the increased partitioning of assimilates to +N axis responds to the difference in sink demand between +N and -N axes.