Crop management strategies for low asparagine grains to limit acrylamide-forming potential

丙烯酰胺是一种2A类致癌化学物质，由游离天冬酰胺和还原糖在油炸、烘烤、烘烤和烘烤谷物、块茎、豆类和其他农作物产品的过程中形成。游离天冬酰胺的浓度决定了谷物产品中丙烯酰胺的含量。游离天冬酰胺浓度因小麦品种而异，但也对环境和作物管理因素（包括作物施肥水平）高度敏感。学生将研究氮肥和硫肥的作用，并确定其他矿物质、灌溉和疾病的影响。他/她将研究小麦中天冬酰胺合成和分解的昼夜调节，研究天冬酰胺合成酶（天冬酰胺的形成）和天冬酰胺酶（天冬酰胺分解）。将对软质小麦定位群体进行分析，以确定游离天冬酰胺浓度的QTL，并对品种进行3B染色体上天冬酰胺合成酶-2基因的存在/缺失筛选。该基因在一些品种中已被证明缺失，并将研究该基因缺失对籽粒中游离天冬酰胺浓度的影响。学生还将比较低和高天冬酰胺颗粒在饼干生产线上的性能。低、中、高天冬酰胺软质小麦品种将在洛桑沃本农场和法国亿滋农场进行田间试验。这些试验将调查不同氮硫比对游离天冬酰胺浓度的影响，其他矿物质的影响，以及灌溉和疾病控制的重要性。试验将持续三年，资金由亿滋提供。学生将监督试验，包括与统计学家一起设计试验和分析数据。该学生还将访问亿滋位于雷丁RSSL的实验室，分析试验中谷物样品中的游离天冬酰胺。不同品种对硫的不同反应。不仅游离天冬酰胺本身的浓度存在品种差异，而且游离天冬酰胺对硫的反应也存在差异，一些低天冬酰胺的品种在缺硫条件下增幅最大。学生将研究这些反应的分子基础。天冬酰胺的合成和分解在拟南芥中被证明是按昼夜调节的，不同的天冬酰胺合成酶在白天和晚上都有活性。学生将在不同的小麦组织（包括谷物）中研究这种现象：哪些酶/基因每天受到调节，在哪些组织中；天冬酰胺的合成和分解在谷物中每天都受到调节吗？在发育过程中会持续多长时间？天冬酰胺小麦中天然含有天冬酰胺酶。学生将研究为什么这些酶不能阻止游离天冬酰胺的积累，以及通过应用植物生长调节剂激活它们的可能性。人口的映射。我们与John Innes小麦遗传学小组合作，制作了一个软质小麦（Claire x Robigus）图谱群体。JIC每年都在增加这一人口，粮食将免费提供供分析使用。测量群体中品系籽粒中的游离天冬酰胺可以使学生确定控制这一重要性状的QTL。B基因组TaASN2基因缺失。学生将在巴黎附近萨克雷的亿滋研发中心比较低、中、高天芦笋颗粒的小规模饼干生产，评估原料中游离天芦笋浓度相对于生产过程中其他方面的重要性，不同颗粒的相对功能，以及在一个典型的生产过程中消耗了多少游离天芦笋。饼干中形成的丙烯酰胺将在亿滋实验室进行测量。

Acrylamide is a Group 2A carcinogenic chemical that forms from free asparagine and reducing sugars during the frying, baking, roasting and toasting of foods derived from grains, tubers, beans and other crop products. Free asparagine concentration determines the amount of acrylamide that forms in cereal products. Free asparagine concentration differs between wheat varieties but is also highly responsive to environmental and crop management factors, including the level of fertilization provided to the crop. The student will look at the role of nitrogen and sulphur fertilization, and determine the effects of other minerals, irrigation and disease. He/she will investigate diurnal regulation of asparagine synthesis and breakdown in wheat, looking at both asparagine synthetases (formation of asparagine) and asparaginases (asparagine breakdown). A soft wheat mapping population will be analysed to identify QTL for free asparagine concentration, and varieties will be screened for the presence/absence of an asparagine synthetase-2 gene on Chromosome 3B: this gene has been shown to be missing in some varieties, and the effect of the loss of this gene on free asparagine concentration in the grain will be investigated. The student will also compare the performance of low and high asparagine grains in biscuit production lines. Low, medium and high asparagine soft wheat varieties will be grown in field trials at the Rothamsted Woburn farm site and at Mondelez sites in France. The trials will investigate the effects of different nitrogen: sulphur ratios on free asparagine concentration, the effects of other minerals, and the importance of irrigation and disease control. The trials will run for three years, with funding provided by Mondelez. The student will oversee the trials, including working with a statistician on designing the trials and analysing the data. The student will also visit the Mondelez laboratory in Reading RSSL to analyse free asparagine in grain samples from the trials.Differential sulphur responses between varieties. There are not only varietal differences in free asparagine concentration per se but also in the response of free asparagine to sulphur, with some low asparagine varieties showing the largest increases under sulphur deficiency. The student will investigate the molecular basis of these responses. Diurnal regulation Asparagine synthesis and breakdown has been shown to be diurnally regulated in Arabidopsis, with different asparagine synthetases active during the day and night. The student will investigate this phenomenon in different wheat tissues, including grain: which enzymes/genes are diurnally regulated, in which tissues; is asparagine synthesis and breakdown diurnally regulated in the grain and for how long during development?AsparaginasesWheat grain naturally contains asparaginase enzymes. The student will investigate why these enzymes fail to prevent the accumulation of free asparagine, and the potential for activating them by application of a plant growth regulator. Mapping population. We have produced a soft wheat (Claire x Robigus) mapping population in collaboration with the John Innes Wheat Genetics Group. This population is being grown annually at JIC and grain will be made available free of charge for analysis. Measurement of free asparagine in the grain of the lines in the population could enable the student to identify QTL controlling this important trait. Deletion of B genome TaASN2 gene. The student will compare low, medium and high asparagine grains in the manufacture of small-scale biscuits at the Mondelez R&D Centre in Saclay, near Paris, assessing the importance of free asparagine concentration in the raw material relative to other aspects of the process, the relative functionality of different grains, and how much free asparagine is used up in a typical manufacturing process. Acrylamide formed in the biscuits will be measured at the Mondelez laboratory in RU RSSL.