1.
Genome-Wide Association Study of 13 Traits in Maize Seedlings under Low Phosphorus Stress.
Wang, QJ, Yuan, Y, Liao, Z, Jiang, Y, Wang, Q, Zhang, L, Gao, S, Wu, F, Li, M, Xie, W, et al
The plant genome. 2019;(3):1-13
Abstract
Low P stress is a global issue for grain production. Significant phenotypic differences were detected among 13 traits in 356 maize lines under P-sufficient and P-deficient conditions. Significant single nucleotide polymorphisms (SNPs) and low-P stress-responsive genes were identified for 13 maize root traits based on a genome-wide association study. Hap5, harboring 12 favorable SNPs, could enhance strong root systems and P absorption under low-P stress. Phosphorus is an essential macronutrient required for normal plant growth and development. Determining the genetic basis of root traits will enhance our understanding of maize's (Zea mays L.) tolerance to low-P stress. Here, we identified significant phenotypic differences for 13 traits in maize seedlings subjected to P-sufficient and P-deficient conditions. Six extremely sensitive and seven low-P stress tolerant inbreds were selected from 356 inbred lines of maize. No significant differences were observed between temperate and tropical-subtropical groups with respect to trait ratios associated with the adaptation to low-P stress. The broad-sense heritability of these traits ranged from relatively moderate (0.59) to high (0.90). Through genome-wide association mapping with 541,575 informative single nucleotide polymorphisms (SNPs), 551, 1140 and 1157 significant SNPs were detected for the 13 traits in 2012, 2016 and both years combined, respectively, along with 23 shared candidate genes, seven of which overlapped with reported quantitative trait loci and genes for low-P stress. Five haplotypes located in candidate gene GRMZM2G009544 were identified; among these, Hap5, harboring 12 favorable SNP alleles, showed significantly greater values for the root traits studied than the other four haplotypes under both experimental conditions. The candidate genes and favorable haplotypes and alleles identified here provide promising resources for genetic studies and molecular breeding for improving tolerance to abiotic stress in maize.
2.
[Effects of straw returning on maize yield and root system spatial distribution under water stress].
Wang, F, Wang, MJ, Su, SH, Wang, YY, Su, YH, Meng, GX, Sun, Y, Qi, H, Jiang, Y
Ying yong sheng tai xue bao = The journal of applied ecology. 2018;(11):3643-3648
Abstract
To investigate the effects of straw amendments on the yield and root spatial distribution of maize under water stress, an experiment with rainproof shelter was conducted in the field experimental station of Shenyang Agricultural University in 2016 and 2017. The drip irrigation facilities were used to perform water stress treatments. Straw burying (T1) and straw incorporation (T2) as two approaches of straw amendments were conducted combined with three depths of 15 cm (D1), 30 cm (D2), and 45 cm (D3) for straw returning, ploughing tillage at above three depths without straw presence as control in this study. During seedling and silking stages of maize, drought and water logging stresses were introduced respectively to the plants. Our results showed that the yield of maize under S1T1D2 treatment in 2016 was significantly increased by 5.7%-7.1%. Compared with all the rest treatments, the dry weights of lateral roots and deep roots under S1T1D2 treatment were increased by 67.3%-149.9% and 17.9%-116.4%, respectively. The dry matter accumulation in shoot of maize observed from S1T1D2 treatment was significantly lower than those under other treatments, with 2.1%-35.8% reduction. Our results indicated that S1T1D2 could significantly promote the growth and spatial distribution of maize root, accounting to release water stress and keep yield stabilization or promotion. Therefore, 30 cm of straw burying could be used as a suitable approach of straw returning for maize production in northeastern China, where the climate is with a pattern of drought first and waterlogging in later stage.