大豆抗镉和籽粒低积累的分子机理解析

Vast areas of agricultural soils are contaminated with Cadmium(Cd) through the use of super phosphate fertilizers and sewage sludge, and inputs from mining and smelting industries.From the viewpoint of our health and sustainnable agricultural production,minimizing Cd content in their grain is an urgent matter.Selection and breeding of crops for low uptake and accunulation in grain open up new opportunities to minimize Cd in the food chain.To achieve this goal,the genetic components controlling advantageous traits need to be identified to provide an understanding of their molecular mechanisms.In this project, firstly, the genome of two contrast genotypes, Zhonghuang24 (sensitivity, high Cd accumulation) and Huaxia3 (resistance，low Cd accumulation),will be resequenced by the high-throughput sequencing .The structure difference will be revealed through comparing the reads from two genotypes. Secondly, the transcriptome data of root, leaf and seed stressed Cd will be provided by RNA Seq-Atlas. Small RNAs and target genes will be uncovered by high-throughput sequencing. Thirdly, the new markers will be developed based on those information, and map QTLs associated with Cd resistance and low accumulation in soybean in the recombinant inbred line population(F6:7) derived from Zhonghuang24 / Huaxia3. Integrating expression profiling and linkage analysis, we understand the molecular regulating network of tolerance and low cadmium accumulation in soybean and establish the blueprints of molecular design breeding.

土壤镉污染程度和面积日趋严重，从人类健康和农业可持续发展的角度，减少农作物籽粒中镉含量已是农业生产的重要任务，选育低吸收、籽粒低积累的作物品种为我们开辟一条降低镉危害的最经济可持续的线路，而通过解析作物籽粒低积累的遗传基础、理解分子机制才可达到改良籽粒低积累性状的目的。本项目以华夏3号（中抗、低积累）和中黄24（敏感、高积累）及其衍生的F6:7重组自交系群体为材料，首先利用新一代全基因组测序技术分析两亲本间差异位点，开发新标记；然后利用高通量基因表达技术分析两亲本间差异表达的基因（包括编码蛋白和非编码的小分子），开发新标记；再利用重组自交系群体对所开发的标记与镉抗性、籽粒积累数据进行连锁分析，寻找与大豆抗性、低积累的QTL；并对定位信息在育种材料中验证。整合表达谱和连锁分析的信息，理解大豆镉抗性和低积累的分子机制，为开展分子设计育种做准备。

面对土地资源短缺背景下的土地重金属污染的挑战和广大民众对食品安全的关注，农业科学家可以通过育种手段选育抗污染低积累的优良品种，从而在轻度、中度污染的土地上生产出符合要求的安全食品。了解大豆镉抗性和籽粒镉积累的遗传与分子机制是大豆镉抗性和籽粒镉积累分子育种的前提。.本项目在调查了南方大豆生产田重金属污染状况的基础上，首先从200多分大豆育种资源中筛选出镉抗性、籽粒积累不同的5个品种，通过比较发现5个品种间在根系、茎叶和籽粒生理性状存在着显著差异。然后利用新一代全基因组测序技术对两个差异明显的品种华夏3号（中抗、低积累）和中黄24（敏感、高积累）间全基因组进行了测序，发现了529870多个SNP 新标记，同时利用高通量基因表达技术发现在两品种间根系中存在5518差异基因和17个差异miRNA，而在籽粒中存在差异基因2242和差异蛋白21。利用这些信息开发新标记，在以华夏3号（中抗、低积累）和中黄24（敏感、高积累）衍生的F6:7 重组自交系群体为材料对所开发的标记与镉抗性、籽粒积累数据进行了连锁分析，分别找到8个和4个与大豆抗性、低积累的QTL。这些结果有助于理解大豆镉抗性和籽粒积累的分子机制。

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