Nitric Oxide and Regulation of Seed Dormancy

许多植物的成熟种子不容易发芽。这被称为休眠。植物育种者试图选择种子在收获前保持休眠，但在种植时容易发芽的作物。他们没有完全成功，谷物作物过早发芽仍然是一个问题。许多有害杂草的种子具有很强的休眠性，在整个生长季节不规律地发芽。因此，杂草控制是困难的，这可能导致作物产量或质量的严重降低。然而，休眠对于维持自然生态系统至关重要。种子库由休眠的种子组成，存在于土壤中。这些种子可能会休眠多年，只有在接受适当的环境暗示后才会发芽。人们对如何控制农作物和野生物种的休眠很感兴趣。环境条件，如光照和温度，土壤硝酸盐和亚硝酸盐，燃烧植物材料产生的烟雾，以及燃烧化石燃料产生的污染物，对打破休眠和允许种子发芽非常重要。然而，栽培或野生植物的休眠是如何建立和维持的还不清楚。提出了一种假说，即一氧化氮气体（NO）在调节农业和自然生态系统的休眠中起着关键作用。实验提出了两种植物，拟南芥和水稻。这些实验将为阔叶植物和禾本科植物的休眠提供深入的了解。这项研究的目标是揭示休眠和种子对NO的反应的生化和分子机制。有待检验的假设是，拟南芥和大麦种子可以合成NO，NO可以克服这两个物种的种子休眠。内源性NO在调节这些种子的萌发的作用也表明了实验的化合物，可以NO. NO的去除加强种子休眠，减少种子发芽。支持NO作为种子中的天然调节剂的作用来自实验，该实验表明拟南芥和大麦种子可以从亚硝酸盐合成NO。实验提出使用控制气氛，以确定需要多少NO克服种子休眠。这些实验将建立当NO是有效的休眠打破剂，信息，将有助于基因发现实验的设计。其他实验建议建立拟南芥种子如何合成NO。一个生物化学和分子/遗传学的方法将被用来研究如何在拟南芥NO调节休眠。先进的分子生物学技术将被用来监测基因的表达与NO处理的种子。种子表现出缺陷的休眠将被用来调查如何NO功能在休眠，并发现哪些基因是必不可少的休眠。这项研究的更广泛的影响包括农业的重要性，在了解如何休眠的有害杂草是控制。 特别是，一氧化氮控制休眠的机制的阐明可能会导致操作策略的设计。 该提案还将为本科生和研究生提供培训机会，并为高中生和K-12课程开发提供培训机会。

Mature seeds of many plants do not sprout readily. This is referred to as dormancy. Plant breeders have attempted to select for crop plants whose seeds remain dormant until harvest, yet sprout readily when planted. They have not been completely successful, and premature sprouting of cereal crops remains a problem. The seeds of many noxious weeds have strong dormancy and sprout erratically throughout the growing season. Weed control is therefore difficult, and this can result in serious reductions in crop yield or quality. Dormancy, however, is essential for the maintenance of natural ecosystems. Seed banks that consist of dormant seeds persist in soils. These seeds may lie dormant for years and will only sprout after receiving appropriate environment cues. There is great interest in how dormancy of crops and wild species is controlled. Environment conditions such as light and temperature, soil nitrates and nitrites, smoke from burning plant material, and pollutants resulting from the burning of fossil fuels are important in breaking dormancy and allowing seeds to sprout. Yet, how dormancy of cultivated or wild plants is established and maintained is unknown. A hypothesis is advanced that nitric oxide gas (NO) has a key role in regulating dormancy in agricultural and natural ecosystems. Experiments are proposed with two plants, Arabidopsis and rice. These experiments will provide insights into dormancy in broad-leaf plants and the grasses. The goals of the research are to uncover the biochemical and molecular mechanisms that underlie dormancy and the response of seeds to NO. The hypothesis to be tested is that Arabidopsis and barley seeds can synthesize NO and that NO can overcome dormancy in the seeds of both species. A role for endogenous NO in regulating germination of these seeds is also indicated by experiments with compounds that can scavenge NO. Removal of NO strengthens seed dormancy and reduces seed sprouting. Support for a role of NO as a natural regulator in seeds has come from experiments showing that Arabidopsis and barley seeds can synthesize NO from nitrite. Experiments are proposed using controlled atmospheres to determine how much NO is required to overcome dormancy in seeds. These experiments will establish when NO is effective as a dormancy-breaking agent, information that will help in the design of gene discovery experiments. Other experiments are proposed to establish how Arabidopsis seeds synthesize NO. A biochemical and molecular/genetic approach will be used to investigate how NO regulates dormancy in Arabidopsis. Advanced molecular biology techniques will be used to monitor gene expression in seeds treated with NO. Seeds showing defects in dormancy will be used to investigate how NO functions in dormancy and to discover what genes are essential for dormancy.The Broader Impacts of this research include the importance for agriculture in understanding how the dormancy of noxious weeds is controlled. In particular, an elucidation of the mechanisms by which NO controls dormancy could lead to the design of strategies of manipulation. The proposal will also provide training opportunities for undergraduate and graduate students, as well as for the training of high school students and K-12 curricular development.