Duplicate and conquer: multiple homologs of phosphorus-starvation tolerance 1 enhance phosphorus acquisition and sorghum performance on low-P soils

Authors: HUFNAGEL, BARBARA - Federal University Of Minas Gerais; DE SOUSA, SYLVIA - Embrapa; ASSIS, LIDIANNE - Embrapa; GUIMARAES, CLAUDIA - Federal University Of Minas Gerais; LEISER, WILLMAR - International Crops Research Institute For The Semi-Arid Tropics (ICRISAT); CORRADI, GABRIEL - Embrapa; NEGRI, BARBARA - Embrapa; LARSON, BRANDON - Cornell University; SHAFF, JON - Cornell University; PASTINA, MARIA MARTA - Embrapa; BARROS, BEATRIZ - Embrapa; WELTZIEN, EVA - International Crops Research Institute For The Semi-Arid Tropics (ICRISAT); RATTUNDE, HENRY FREDERICK - International Crops Research Institute For The Semi-Arid Tropics (ICRISAT); VIANA, JUAO - Embrapa; CLARK, RANDY - Cornell University; FALCAO, ALEXANDRE - Universidade De Campinas (UNICAMP); GAZAFFI, RODRIGO - Universidad De Sao Paulo; GARCIA, ANTONIO AUGUSTO - Universidad De Sao Paulo; SCHAFFERT, ROBERT - Embrapa; Kochian, Leon; MAGALHAES, JURANDIR - Embrapa

Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/7/2015
Publication Date: 10/1/2014
Citation: Hufnagel, B., De Sousa, S.M., Assis, L., Guimaraes, C.T., Leiser, W., Corradi, G., Negri, B., Larson, B.G., Shaff, J.E., Pastina, M., Barros, B.A., Weltzien, E., Rattunde, H.W., Viana, J.H., Clark, R.T., Falcao, A., Gazaffi, R., Garcia, A.F., Schaffert, R.E., Kochian, L.V., Magalhaes, J.V. 2014. Duplicate and conquer: multiple homologs of phosphorus-starvation tolerance 1 enhance phosphorus acquisition and sorghum performance on low-P soils. Plant Physiology. 166(2):659-677.

Interpretive Summary: Phosphorus (P) is probably the most limiting mineral nutrient for plants. Many of our planet’s soils are low in phosphorus, and this includes approximately half of the world’s agricultural lands. Furthermore, in developed country agriculture P fertilizer not taken up by crop plants ends up polluting ground and surface waters and this is a growing problem in the US. Hence, there is considerable interest in developing plant varieties that are more phosphorus efficient - that is, crops that can produce higher yields while using less soil phosphorus. In this research on sorghum P efficiency (the ability to maintain grain yield on low P soil) we investigated the genetic variability and genetically mapped both P efficiency and root architecture – as root systems with a large number of shallow lateral have been shown to mine the P from low P soils that tends to be fixed in the topsoil. We then conducted another type of genetic mapping to see if sequence variation in a suite of related sorghum genes that are homologs of a recently identified rice P efficiency gene associated with variation in P efficiency and shallow root architecture. WE identified several related genes that appear to control sorghum P efficiency via altering the root architecture towards more and finer shallow roots. These discoveries will set the stage for future discoveries that will ultimately provide plant breeders with the molecular targets for improving crop P efficiency via molecular-assisted breeding.

Technical Abstract: Low soil phosphorus (P) availability is a major constraint for crop production in tropical regions. The rice protein kinase, OsPSTOL1, was previously shown to enhance P acquisition and grain yield in rice under P deficiency. We investigated the role of homologs of OsPSTOL1 in sorghum performance under low P. Association mapping was undertaken in two sorghum association panels phenotyped for P uptake, root system morphology and architecture in hydroponics, and grain yield and biomass accumulation under low soil P conditions in Brazil and/or in Mali. Root length and root surface area were positively correlated with grain yield under low P in the soil, emphasizing the importance of P acquisition efficiency in sorghum adaptation to low P availability. SbPSTOL1 alleles reducing root diameter were associated with enhanced P uptake under low P in hydroponics whereas Sb03g006765 and Sb03g0031680 alleles increasing root surface area also increased grain yield in a low-P soil. SbPSTOL1 genes co-localized with QTL for traits underlying root morphology and dry weight accumulation under low P via linkage mapping. Consistent allelic effects for enhanced sorghum performance under low P between association panels, including enhanced grain yield under low P in the soil in Brazil, points towards a relatively stable role for Sb03g006765 across genetic backgrounds and environmental conditions. This study indicates that multiple SbPSTOL1 genes have a more general role in the root system, enhancing not only root morphology traits but also changing root system architecture, which leads to grain yield gain under low P availability in the soil.