Identification and characterization of a novel stay-green QTL that increases yield in maize

Jun Zhang, Kevin A. Fengler, John L. Van Hemert, Rajeev Gupta, Nick Mongar, Jindong Sun, William B. Allen, Yang Wang, Benjamin Weers, Hua Mo, Renee Lafitte, Zhenglin Hou, Angela Bryant, Farag Ibraheem, Jennifer Arp, Kankshita Swaminathan, Stephen P. Moose, Bailin Li, Bo Shen

Research output: Contribution to journalArticlepeer-review


Functional stay-green is a valuable trait that extends the photosynthetic period, increases source capacity and biomass and ultimately translates to higher grain yield. Selection for higher yields has increased stay-green in modern maize hybrids. Here, we report a novel QTL controlling functional stay-green that was discovered in a mapping population derived from the Illinois High Protein 1 (IHP1) and Illinois Low Protein 1 (ILP1) lines, which show very different rates of leaf senescence. This QTL was mapped to a single gene containing a NAC-domain transcription factor that we named nac7. Transgenic maize lines where nac7 was down-regulated by RNAi showed delayed senescence and increased both biomass and nitrogen accumulation in vegetative tissues, demonstrating NAC7 functions as a negative regulator of the stay-green trait. More importantly, crosses between nac7 RNAi parents and two different elite inbred testers produced hybrids with prolonged stay-green and increased grain yield by an average 0.29 megagram/hectare (4.6 bushel/acre), in 2 years of multi-environment field trials. Subsequent RNAseq experiments, one employing nac7 RNAi leaves and the other using leaf protoplasts overexpressing Nac7, revealed an important role for NAC7 in regulating genes in photosynthesis, chlorophyll degradation and protein turnover pathways that each contribute to the functional stay-green phenotype. We further determined the putative target of NAC7 and provided a logical extension for the role of NAC7 in regulating resource allocation from vegetative source to reproductive sink tissues. Collectively, our findings make a compelling case for NAC7 as a target for improving functional stay-green and yields in maize and other crops.

Original languageEnglish (US)
Pages (from-to)2272-2285
Number of pages14
JournalPlant Biotechnology Journal
Issue number12
StatePublished - Dec 1 2019


  • yield
  • QTL
  • stay-green
  • nitrogen remobilization
  • photosynthesis
  • proteolysis

ASJC Scopus subject areas

  • Biotechnology
  • Agronomy and Crop Science
  • Plant Science


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