Relationship of IAD index to internal quality attributes of apples treated with 1-methylcyclopropene and stored in air or controlled atmospheres

The research was conducted to evaluate the relationship between I_AD index (index of absorption difference between 670 and 720 nm) values and internal quality attributes of apples treated with 1-methylcyclopropene (1-MCP) and stored in air and controlled atmospheres (CA). Apples of ‘8S6923’ (Aurora Golden Gala™), ‘Fuji’ and ‘Royal Gala’ were tested. The results with Aurora Golden Gala™ show that I_AD index values were maintained at higher levels if the fruit were stored in CA and that 1-MCP had no significant effect on retaining at-harvest values. The I_AD values correlated with chlorophyll a content in the peel (R² = 0.95, P < 0.0001), but not with chlorophyll b content, internal ethylene levels, firmness or titratable acidity. ‘Royal Gala’ apples showed a similar response to Aurora Golden Gala™ apples, showing no correlation between I_AD index values and internal quality attributes of those apples when treated with 1-MCP and/or CA. In contrast, ‘Fuji’ apples showed a relationship between I_AD index value changes and internal ethylene concentrations (R² = 0.67, P < 0.05) and titratable acidity changes (R² = 0.89, P < 0.01), but not firmness. These results suggest that when 1-MCP and/or CA are applied to apples after harvest, that I_AD index values do not consistently correlate to any internal quality attributes other than peel chlorophyll a content.     

基于GBS技术开展柚类资源群体遗传评价并发掘酸含量相关基因

【目的】弄清我国柚类种质资源的起源与演化、群体遗传结构和多样性水平，高效利用柚类自然资源群体发掘与果实重要品质性状相关的基因，为柚类种质资源群体的遗传结构研究、起源演化和柚类种质创新提供重要的理论及实践依据。【方法】利用国家果树种质重庆柑橘资源圃中保存的具有广泛遗传多样性和不同地理来源的282份柚类资源作为材料，采用Eco R I限制性内切酶消化基因组DNA后构建GBS文库，然后进行Illumina HiSeq PE150二代测序获得短读序列，通过BWA软件将序列映射到柚参考基因组上，利用SAMTOOLS软件鉴定SNP位点。依据SNP的基因分型结果，进行主成分分析和群体结构分析,并采用邻接法构建系统演化树，分析亚群的遗传多样性水平。选择23个低酸种质和32个高酸种质构成两个群体进行Fst、XP-CLR分析，同时利用282个柚类种质的基因型数据与果实可滴定酸含量的表型数据进行GWAS全基因组关联分析。【结果】利用GBS简化基因组测序技术对282份柚类种质进行测序，获得201.66 Gb的原始测序数据，每个样本的平均测序数据量为0.72 Gb，经过测序深度为5×次要等位基因频率>0....