Can natural variation in grain P concentrations be exploited in rice breeding to lower fertilizer requirements?

Abstract

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.

A strategy to optimize soil phosphorus reserve: A study based on native maize of Mexico and genotype selection

“…Dicho requerimiento, sin embargo, suele exceder las necesidades de la planta. Por consiguiente, es posible reducir la concentración de P sin afectar los procesos fisiológicos del cultivo (Wang et al, 2017;Han et al, 2022;Houssni et al, 2024). Diversos estudios señalan que, la reducción en la acumulación de fitato (de 46% a 75%) en la semilla de arroz (Zhao et al, 2016;Perera et al, 2018), trigo (Kenzhebayeva et al, 2019;Frittelli et al, 2023), maíz (Raboy, 2020) y garbanzo (Wang et al, 2021) no afecta la germinación, vigor de la plántula y desarrollo del cultivo.…”

“…Lo anterior señala que, la reserva de P en la semilla es suficiente para cubrir la demanda de la plántula durante su crecimiento, por lo menos, de 10 a 17 días después de la germinación (Nadeem et al, 2011). Posteriormente, el crecimiento del cultivo dependerá de la eficiencia de la raíz para adquirir el P del suelo y/o fertilizante y de los patrones de movilización del nutriente hacia la semilla desarrollo (Wang et al, 2017;Cong et al, 2020).…”

A Natural Low Phytic Acid Finger Millet Accession Significantly Improves Iron Bioavailability in Indian Women

“…It might appear that the more sensible and sustainable option is to improve iron absorption by finding or developing low phytic acid cereal or millet grains for farming. Strategies to reduce the grain phytic acid (GPA) content of grain crops include either the development of low GPA mutants by altering the biosynthetic pathway and transport genes ( 26 ), or the identification and selection of natural variants with a low GPA content ( 27 , 28 ).…”

Contribution of External and Internal Phosphorus Sources to Grain P Loading in Durum Wheat (Triticum durum L.) Grown Under Contrasting P Levels

“…Phosphorus in grains is mainly stored in the form of phytate and play a crucial role in supplying P for seedlings before root development (Raboy, 2009;Nadeem et al, 2011;White and Veneklaas, 2012). However, the concentrations of P in grains are often over the need for germination and plant establishment Pariasca-Tanaka et al, 2015;Wang et al, 2017). For example, Julia et al (2018) reported that rice growth and development was unaffected by seed P concentration at seedling stage because root P uptake commences at the very earliest stages of plant development (two days after germination).…”