Mechanisms of nitrate accumulation under resource-independent plant competition.

资源独立植物竞争下硝酸盐积累的机制。

• 批准号: RGPIN-2022-03454
• 负责人: Swanton, Clarence
• 金额: $ 2.04万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763552
• 关键词: Mechanisms; nitrate; accumulation; under; resource

Resource-independent weed competition is an important stress factor that not only affects early development of crop seedlings but also exerts long-lasting effects even after weed removal resulting in significant reductions in yield potential. These effects result from the central importance of far-red light reflected from neighbouring weeds that inactivate phytochrome photoreceptors. Recently, we found a direct link between increasing duration of weed presence and decreases in photosynthetic efficiency, CO2 assimilation, and yield potential, which could not be recovered if weed presence extended to reproductive stages. Photosynthesis and respiration, however, more than any other physiological processes are integrated with nitrogen assimilation. Therefore, the knowledge of the effects of neighbouring weeds on nitrate assimilation in major crop plants is pivotal to making progress in the development of weed management strategies and nitrogen fertilizer application under weed stress. Our laboratory has shown that nitrate accumulation in the model plant Arabidopsis and maize is an early response to neighbouring weeds and simulated far-red light. This response appears to be due to reduced activity of a major enzyme in the nitrate assimilation pathway. Despite establishing this link, we cannot exclude the possibility of the involvement of nitrate transporters and in this proposal this possibility will be investigated by conducting high throughput sequencing. Further, nitrate accumulation in Arabidopsis in response to neighbouring weeds appears to be independent of phytochrome B photoreceptor inactivation. We hypothesize that nitrate accumulation in maize under resource-independent competition may cause nitrate limitation or inadequate nitrate utilization, which if maintained for some time after weed removal, affects early development and subsequent performance of maize. Therefore, two major objectives of our proposal are (1) to elucidate the molecular mechanisms of nitrate accumulation in response to resource-independent competition under controlled environment using maize mutants deficient in phytochrome B photoreceptor and (2) extend our research to field conditions and determine the relationship between the increasing duration of weed presence and nitrate accumulation and subsequent performance of maize following weed removal. The new information generated as the outcome of this research are appropriate for training of highly qualified personnel in photobiology and weed research and open up avenues for research on new far-red light actions that are independent of phytochrome inactivation. In addition, the new information can be transferred to field biologist and farmers to devise weed control plans prior to critical periods for weed control and mitigate not only the impact of resource-independent weed competition on major crop plants but also the impact of excess nitrate on the environment.

资源非依赖性杂草竞争是一个重要的胁迫因素，它不仅影响作物幼苗的早期发育，而且即使在除草后也会产生长期影响，导致产量潜力显著降低。这些影响是由于邻近杂草反射的远红光使光敏色素光感受器失活而产生的。最近，我们发现杂草存在时间的增加与光合效率、CO2同化和产量潜力的降低之间存在直接联系，如果杂草存在延长到生殖阶段，则无法恢复。然而，光合作用和呼吸作用比其他任何生理过程都更离不开氮同化。因此，了解邻近杂草对主要作物硝酸盐同化的影响对杂草管理策略的制定和杂草胁迫下氮肥施用的进展至关重要。我们的实验室已经证明，硝酸盐在模式植物拟南芥和玉米中的积累是对邻近杂草和模拟远红光的早期反应。这种反应似乎是由于硝酸盐同化途径中一种主要酶的活性降低。尽管建立了这种联系，但我们不能排除硝酸盐转运体参与的可能性，在本提案中，将通过进行高通量测序来调查这种可能性。此外，拟南芥对邻近杂草的硝酸盐积累似乎与光敏色素B光感受器失活无关。我们推测，在资源非依赖性竞争条件下，玉米体内的硝酸盐积累可能导致硝酸盐限制或硝酸盐利用不足，如果这种情况在除草后持续一段时间，将影响玉米的早期发育和后期生产性能。因此，我们提出的两个主要目标是：(1)阐明利用缺乏光敏色素B光受体的玉米突变体在受控环境下响应资源独立竞争时硝酸盐积累的分子机制；(2)将我们的研究扩展到田间条件，确定杂草存在时间的增加与硝酸盐积累和杂草去除后玉米的后续性能之间的关系。本研究结果为培养高素质的光生物学和杂草研究人员提供了新的信息，并为研究独立于光敏色素失活的新的远红光作用开辟了途径。此外，新的信息可以传递给野外生物学家和农民，在杂草控制的关键时期之前制定杂草控制计划，不仅可以减轻资源独立的杂草竞争对主要作物的影响，还可以减轻过量硝酸盐对环境的影响。