不同氮水平下水稻钾吸收及全基因组关联分析

以业已完成深度重测序的134份水稻地方种质资源为材料,在大田栽培条件下按不施氮(N0),施96kg hm^–2纯氮(N1)和施192kg hm^–2纯氮(N2)3种氮肥水平,检测了分蘖盛期植株的钾含量、植株干重和钾积累。结果表明,水稻钾含量、植株干重和钾积累在N0、N1、N2三种氮肥处理下均呈正态分布,表型变异丰富。植株干重和钾积累与施氮量呈极显著正相关,钾含量与施氮量相关性不显著;钾含量与植株干重呈负相关,钾含量与钾积累相关性不显著,而植株干重与钾积累呈极显著正相关。在3个施氮水平下,籼稻的钾含量极显著低于粳稻,籼稻的干重和钾积累都极显著高于粳稻。全基因组关联分析发现,在3个氮肥水平下检测到12个显著相关位点,其中钾积累、钾含量和植株干重的显著相关位点分别有2、5和5个。在N1水平下,位于第6染色体上与钾含量相关的SNP(Chr6_1,524,776)的显著性峰候选区包含与钾离子转运蛋白互作的RUPO基因。根据钾含量的差异,鉴定出3个钾含量与低氮响应有关的SNP位点,1个位点与高氮响应有关,而位于第10染色体上的显著性位点Chr10_2,822,026对低氮和高氮均有响应,该区域的4个候选基因的表达在不同氮水平间存在差异。

Potassium uptake and genome-wide association analysis of rice under different nitrogen levels

A total of 134 resequenced rice landraces were used for assessing the potassium content, plant dry weight and potassium accumulation at three different nitrogen levels including no nitrogen fertilizer (N0), 96 kg ha ^-1 (N1), and 192 kg ha ^-1 (N2) under normal field cultivation, respectively. All the three traits displayed normal distribution with abundant variations under N0, N1, and N2 nitrogen levels, respectively. K accumulation and plant dry weight showed positive correlation with nitrogen levels. Meanwhile, the negative correlation was detected between K content and dry weight, and there was positive correlation between dry weight and K accumulation. In addition, the K content showed significantly lower in indica than in japonica, while the dry weight and K accumulation in indica were significantly higher than those in japonica. A total of 12 SNPs presented significant association with the potassium content, plant dry weight and potassium accumulation under three diferent nitrogen levels, including two SNPs for K accumulation, five SNPs for K content and five SNPs for dry weight. A SNP (Chr6_1,524,776) associated with potassium content on chromosome 6 was detected at N1 level. Its flank contained a receptor-like kinase, RUPO, which interacts with potassium transporters in rice. According to the difference of potassium content, one SNP and three SNPs were identified with high nitrogen and low nitrogen response, respectively. While four candidate genes closed to the SNP (Chr10_2,822,026) were associated to K content relatively changed under both high nitrogen and low nitrogen levels, showing different expression levels under different nitrogen levels.