title: Root cortical aerenchyma enhances nitrogen acquisition from low-nitrogen soils in maize.
abstract: Suboptimal nitrogen (N) availability is a primary constraint for crop production in developing nations, while in rich nations, intensive N fertilization carries substantial environmental and economic costs. Therefore, understanding root phenes that enhance N acquisition is of considerable importance. Structural-functional modeling predicts that root cortical aerenchyma (RCA) could improve N acquisition in maize (Zea mays). We evaluated the utility of RCA for N acquisition by physiological comparison of maize recombinant inbred lines contrasting in RCA grown under suboptimal and adequate N availability in greenhouse mesocosms and in the field in the United States and South Africa. N stress increased RCA formation by 200% in mesocosms and by 90% to 100% in the field. RCA formation substantially reduced root respiration and root N content. Under low-N conditions, RCA formation increased rooting depth by 15% to 31%, increased leaf N content by 28% to 81%, increased leaf chlorophyll content by 22%, increased leaf CO2 assimilation by 22%, increased vegetative biomass by 31% to 66%, and increased grain yield by 58%. Our results are consistent with the hypothesis that RCA improves plant growth under N-limiting conditions by decreasing root metabolic costs, thereby enhancing soil exploration and N acquisition in deep soil strata. Although potential fitness tradeoffs of RCA formation are poorly understood, increased RCA formation appears be a promising breeding target for enhancing crop N acquisition.
authors.affiliation: Intercollege Graduate Degree Program in Plant Biology (P.S., K.M.B., J.P.L.) and Department of Plant Science (E.A.N., J.G.C., K.M.B., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802.
authors.forename: Patompong
authors.initials: P
authors.lastname: Saengwilai
authors.affiliation: Intercollege Graduate Degree Program in Plant Biology (P.S., K.M.B., J.P.L.) and Department of Plant Science (E.A.N., J.G.C., K.M.B., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nord
authors.affiliation: Intercollege Graduate Degree Program in Plant Biology (P.S., K.M.B., J.P.L.) and Department of Plant Science (E.A.N., J.G.C., K.M.B., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802.
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Chimungu
authors.affiliation: Intercollege Graduate Degree Program in Plant Biology (P.S., K.M.B., J.P.L.) and Department of Plant Science (E.A.N., J.G.C., K.M.B., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802.
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Brown
authors.affiliation: Intercollege Graduate Degree Program in Plant Biology (P.S., K.M.B., J.P.L.) and Department of Plant Science (E.A.N., J.G.C., K.M.B., J.P.L.), Pennsylvania State University, University Park, Pennsylvania 16802 jpl4@psu.edu.
authors.forename: Jonathan Paul
authors.identifier: http://orcid.org/0000-0002-7265-9790
authors.initials: JP
authors.lastname: Lynch
mesh_terms: D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D010788:Photosynthesis; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D003313:Zea mays / Q000378:metabolism* / Q000502:physiology
chemical_list: D012987:Soil; D009584:Nitrogen