Guizhou Institute of Upland Food Crops, Guizhou Academy of Agricultural Sciences, Guiyang, Guizhou, China.
PLoS One. 2013;8(2):e56227. doi: 10.1371/journal.pone.0056227. Epub 2013 Feb 15.
The low lysine content of waxy maize cannot meet the nutritional requirements of humans, livestock, or poultry. In the present study, the high-lysine genes o2 and o16 were backcrossed into wx lines using the maize high-lysine inbreds TAIXI19 (o2o2) and QCL3021 (o16o16) as donors and the waxy maize inbred line QCL5019 (wxwx) as a receptor. In the triple-cross F1, backcross, and inbred generations, the SSR markers phi027 and phi112 within the wx and o2 genes and the SSR marker umc1121 linked to the o16 gene were used for foreground selection. Background selection of the whole-genome SSR markers was performed for the selected individuals. The grain lysine content was determined using the dye-binding lysine method. The waxiness of the grain was determined with the I2-KI staining and dual-wavelength spectrophotometric analysis. The BC2F2 generation included 7 plants of genotype wxwxo2o2O16_, 19 plants of genotype wxwxo16o16O2_, and 3 plants of genotype wxwxo2o2o16o16. In these seeds, the average amylopectin content was 96.67%, 96.87%, and 96.62%, respectively, which is similar to that of QCL5019. The average lysine content was 0.555%, 0.380%, and 0.616%, respectively, representing increases of 75.1%, 19.9%, 94.3%, respectively, over QCL5019. The average genetic background recovery rate of the BC2F3 families was 95.3%, 94.3%, 94.2%, respectively. Among these 3 wxwxo2o2O16O16 families, 4 wxwxo2o2O16o16 families, and 3 wxwxo2o2o16o16 families, the longest imported parent donor fragment was 113.35 cM and the shortest fragment was 11.75 cM. No significant differences in lysine content were found between the BC2F4 seeds and the BC2F3 seeds in these 10 families. This allowed us to increase the lysine content of waxy corn and produce seeds with excellent nutritional characteristics suitable for human consumption, animal feed, and food processing. This may be of significance in the breeding of high-quality corn and in improvement of the nutrition of humans, livestock, and poultry.
蜡质玉米的赖氨酸含量低，不能满足人类、家畜和家禽的营养需求。本研究利用高赖氨酸玉米自交系 TAIXI19（o2o2）和 QCL3021（o16o16）作为供体，蜡质玉米自交系 QCL5019（wxwx）作为受体，将高赖氨酸基因 o2 和 o16 回交到 wx 品系中。在三交 F1、回交和自交世代中，利用 wx 和 o2 基因内的 SSR 标记 phi027 和 phi112 以及与 o16 基因连锁的 SSR 标记 umc1121 进行前景选择。对选择的个体进行全基因组 SSR 标记的背景选择。采用染料结合赖氨酸法测定籽粒赖氨酸含量，采用 I2-KI 染色和双波长分光光度法测定籽粒蜡质含量。BC2F2 代包括 7 株基因型 wxwxo2o2O16_、19 株基因型 wxwxo16o16O2_和 3 株基因型 wxwxo2o2o16o16。在这些种子中，直链淀粉含量分别为 96.67%、96.87%和 96.62%，与 QCL5019 相似。赖氨酸含量分别为 0.555%、0.380%和 0.616%，分别比 QCL5019 增加 75.1%、19.9%和 94.3%。BC2F3 家系的平均遗传背景恢复率分别为 95.3%、94.3%和 94.2%。在这 3 个 wxwxo2o2O16O16 家系、4 个 wxwxo2o2O16o16 家系和 3 个 wxwxo2o2o16o16 家系中，最长的导入亲本供体片段为 113.35cM，最短片段为 11.75cM。在这 10 个家系的 BC2F4 种子中，赖氨酸含量与 BC2F3 种子无显著差异。这使得我们能够提高蜡质玉米的赖氨酸含量，并生产出具有优良营养特性、适合人类食用、动物饲料和食品加工的种子。这可能对优质玉米的选育和人类、家畜和家禽的营养改善具有重要意义。
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