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Proanthocyanidins in Cereals and Brassicaceae: A Cross-Species Approach on their Roles for Seed-Coat Biophysical Properties, Dormancy and Germination

谷物和十字花科中的原花青素：跨物种方法研究其对种皮生物物理特性、休眠和发芽的作用

基本信息

批准号：
BB/M000583/1
负责人：
Gerhard Leubner
金额：
$ 87.71万
依托单位：
Royal Holloway University of London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FM000583%2F1
关键词：
Proanthocyanidins Cereals Brassicaceae Cross Species

项目摘要

Seeds are at the beginning and end of the life cycle of all higher plants. Many wild species show a high degree of dormancy that prevents seeds from germinating immediately after shedding, and delays germination until more favourable conditions for plant growth are encountered. Domestication of crop plants from such wild species has often resulted in significant loss of dormancy as prehistoric farmers selected in favour of seeds with rapid germination. However, some degree of dormancy is an important quality trait in many crops, as it prevents seeds from germinating prematurely while still attached to the mother plant. This is a serious problem in cereals such as bread wheat, because wet weather near harvest time can cause seeds to germinate within the ear ("pre-harvest sprouting"). This causes release of enzymes that partially degrade of the starch (flour) and thereby impacts negatively on bread-making quality. Sprout-induced seeds produce so much enzyme that a small proportion of such grains within a crop can result in the entire harvest being suitable only as animal feed, with consequent economic loss to the farmer.Thus, too little dormancy can result in pre-harvest sprouting, while too much dormancy may lead to non-uniform germination in the field. This is important for high-quality seeds also of broadleaf crop species from the cabbage family (Brassicaceae). The speed and uniformity of germination of crop seeds after sowing is an equally important seed quality trait and together with dormancy directly affects crop production. Clearly, an understanding of the processes that determine the level of dormancy and the speed of germination are essential to enable us to design and breed new varieties of crop plants which perform well even in stressful environments (under climate change). One clear contributory factor in many species is the seed coat, damage to which or removal can result in complete loss of dormancy and in faster germination. This appears to be associated with the presence of reddish-brown tannins in the seed coat; the importance of these seed coat tannins is clear from plants that have lost the ability to make the compounds, resulting in pale-coloured seeds with lower levels of dormancy and faster germination. For example, white-grained wheat is much more prone to pre-harvest sprouting than a red-grained variety and is therefore difficult to grow successfully in the wet UK climate. White-grained wheat has several advantages over red-grained types, including a higher yield of white flour and the production of "white wholemeal" with the taste of white bread but the fibre and nutrient properties of normal red wholemeal.There are several ways in which the tannins in the seed coat could affect dormancy and germination: they may increase the physical strength of the coat to prevent germination, they may affect the permeability of the coat to water, hormones or oxygen, which are required for germination, or precursors or metabolites of the tannins might directly suppress seed germination. These different hypotheses have not previously been directly tested, but our collaborative team has developed the materials and the methods through which we can examine each in turn. We plan to look at two species, cress and wheat, as models for eudicot (broadleaf) and monocot (cereal) species, respectively. We have developed varieties of both species that are impaired in the late steps in tannin production in the seed coat, so that we can examine the effects on tannins for seed coat properties, on dormancy and the speed of germination. At the same time we have pioneered methods for measuring the strength, extensibility and permeability of the isolated seed coats. We will relate these properties to the interaction with environmental factors such as temperature, to provide a comprehensive understanding of the roles of tannins in coat-imposed dormancy and germination speed of seeds.

种子是所有高等植物生命周期的起点和终点。许多野生物种表现出高度的休眠，这阻止了种子在落叶后立即萌发，并推迟了萌发，直到遇到更有利的植物生长条件。驯化这些野生物种的作物植物往往导致休眠状态的显著丧失，因为史前农民选择了快速萌发的种子。然而，在许多作物中，一定程度的休眠是一种重要的质量性状，因为它防止种子在仍附着在母体上时过早萌发。这在面包小麦等谷物中是一个严重的问题，因为临近收获季节的潮湿天气会导致种子在穗内发芽(“收获前发芽”)。这会导致酶的释放，使淀粉(面粉)部分降解，从而对面包制作质量产生负面影响。发芽诱导的种子产生大量的酶，以至于作物中这种谷物的一小部分可能导致整个收成只适合作为动物饲料，从而给农民带来经济损失。因此，太少的休眠可能导致收获前发芽，而太多的休眠可能导致田间发芽不均匀。这对于高质量的种子以及来自卷心菜家族(十字花科)的阔叶作物物种来说都是重要的。作物种子播种后萌发的速度和整齐度是一项同样重要的种子品质性状，与休眠状态一起直接影响作物产量。显然，对决定休眠程度和萌发速度的过程的了解对于我们设计和培育即使在紧张的环境中(在气候变化下)也表现良好的作物新品种至关重要。在许多物种中，一个明显的促成因素是种皮，对种皮的破坏或去除可以导致休眠的完全丧失和更快的萌发。这似乎与种皮中存在的红棕色单宁有关；这些种皮单宁的重要性从失去制造化合物的能力的植物中可见一斑，导致浅色种子休眠程度较低，萌发速度较快。例如，白粒小麦比红粒小麦更容易在收获前发芽，因此在英国潮湿的气候下很难成功种植。与红色籽粒小麦相比，白色籽粒小麦有几个优势，包括更高的白色面粉产量和“白色全麦”的生产，具有白面包的味道，但具有正常红色全麦的纤维和营养特性。种皮中的单宁可以通过几种方式影响休眠和萌发：它们可能增加种皮的体力以防止萌发，它们可能影响种皮对水、激素或氧气的渗透性，而水、激素或氧气是萌发所必需的，或者单宁的前体或代谢物可能直接抑制种子萌发。这些不同的假说以前没有被直接测试过，但我们的合作团队已经开发了材料和方法，我们可以通过这些材料和方法来轮流检验每个假说。我们计划研究两个物种，水芹和小麦，分别作为真叶植物(阔叶植物)和单子叶植物(谷类)的模型。我们开发了在种皮中单宁产生的后期阶段受到损害的两个物种的品种，以便我们可以检查单宁对种皮特性、休眠和萌发速度的影响。同时，我们还开创了测量隔离种皮的强度、延伸性和渗透性的方法。我们将把这些性质与温度等环境因素的相互作用联系起来，以全面了解单宁在种子被套休眠和萌发速度中的作用。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Cold-induced secondary dormancy and its regulatory mechanisms in Beta vulgaris.

DOI：
10.1111/pce.14264
发表时间：
2022-04
期刊：
PLANT CELL AND ENVIRONMENT
影响因子：
7.3
作者：
Hourston, James E.;Steinbrecher, Tina;Chandler, Jake O.;Perez, Marta;Dietrich, Katrin;Tureckova, Veronika;Tarkowska, Danuse;Strnad, Miroslav;Weltmeier, Fridtjof;Meinhard, Juliane;Fischer, Uwe;Fiedler-Wiechers, Karin;Ignatz, Michael;Leubner-Metzger, Gerhard
通讯作者：
Leubner-Metzger, Gerhard

Encyclopedia of Applied Plant Sciences

应用植物科学百科全书