Wang Fanmiao, King James Douglas Morrison, Rose Terry, Kretzschmar Tobias, Wissuwa Matthias
Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, Japan.
Crop, Livestock and Environment Division, Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi, Tsukuba, Ibaraki, Japan.
PLoS One. 2017 Jun 26;12(6):e0179484. doi: 10.1371/journal.pone.0179484. eCollection 2017.
Agricultural usage of phosphorus (P) is largely driven by the amount of P removed from fields in harvested plant matter as offtake needs to be balanced by P fertilizer application. Reducing P concentration in grains is a way to decrease P offtake and reduce P fertilizer requirements or soil P mining where insufficient P is applied. Our objective was to assesses the genotypic variation for grain P concentration present within the rice gene pool and resolve to what extent it is affected by environment (P supply) or associated with genetic factors. About 2-fold variation in grain P concentrations were detected in two rice diversity panels, however, environmental effects were stronger than genotype effects. Genome wide association studies identified several putative loci associated with grain P concentrations. In most cases this was caused by minor haplotype associations with high grain P concentrations while associations with reduced P concentrations were identified on chromosomes 1, 6, 8, 11 and 12. Only the latter type of locus is of interest in breeding for reduced P concentrations and the most promising locus was at 20.7 Mb on chromosome 8, where a rare haplotype that was absent from all modern varieties studied reduced grain P concentration by 9.3%. This and all other loci were not consistently detected across environments or association panels, confirming that genetic effects were small compared to effects of environment. We conclude that the genetic effects detected were not sufficiently large or consistent to be of utility in plant breeding. Instead breeding efforts may have to rely on small to medium effect mutants already identified and attempt to achieve a more pronounced reduction in grain P concentration through the introgression of these mutants into a single genetic background.
磷（P）在农业中的使用很大程度上取决于收获的植物物质从田间带走的磷量，因为产出需要通过施用磷肥来平衡。降低谷物中的磷浓度是减少磷产出和降低磷肥需求或在磷肥施用量不足时减少土壤磷消耗的一种方法。我们的目标是评估水稻基因库中存在的谷物磷浓度的基因型变异，并确定其受环境（磷供应）影响的程度或与遗传因素的关联程度。在两个水稻多样性群体中检测到谷物磷浓度存在约2倍的变异，然而，环境效应比基因型效应更强。全基因组关联研究确定了几个与谷物磷浓度相关的假定基因座。在大多数情况下，这是由与高谷物磷浓度相关的小单倍型关联引起的，而在第1、6、8、11和12号染色体上发现了与降低磷浓度相关的关联。只有后一种类型的基因座在培育低磷浓度品种方面具有意义，最有前景的基因座位于第8号染色体上20.7 Mb处，在所有研究的现代品种中都不存在的一种罕见单倍型使谷物磷浓度降低了9.3%。这个以及所有其他基因座在不同环境或关联群体中并未一致检测到，这证实了与环境效应相比，遗传效应较小。我们得出结论，检测到的遗传效应不够大或一致，无法在植物育种中发挥作用。相反，育种工作可能不得不依赖已经鉴定出的中小效应突变体，并尝试通过将这些突变体导入单一遗传背景来更显著地降低谷物磷浓度。
