AUTHOR=Cao Huairong , Qi Shengdong , Sun Mengwei , Li Zehui , Yang Yi , Crawford Nigel M. , Wang Yong 

TITLE=Overexpression of the Maize ZmNLP6 and ZmNLP8 Can Complement the Arabidopsis Nitrate Regulatory Mutant nlp7 by Restoring Nitrate Signaling and Assimilation

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01703

DOI=10.3389/fpls.2017.01703

ISSN=1664-462X

ABSTRACT=<p>Nitrate is a key nutrient that affects maize growth and yield, and much has yet to be learned about nitrate regulatory genes and mechanisms in maize. Here, we identified nine <italic>ZmNLP</italic> genes in maize and analyzed the functions of two <italic>ZmNLP</italic> members in nitrate signaling. qPCR results revealed a broad pattern of expression for <italic>ZmNLP</italic> genes in different stages and organs with the highest levels of transcript expression of <italic>ZmNLP6</italic> and <italic>ZmNLP8</italic>. When <italic>ZmNLP6</italic> and <italic>ZmNLP8</italic> were overexpressed in the <italic>Arabidopsis</italic> nitrate regulatory gene mutant <italic>nlp7-4</italic>, nitrate assimilation and induction of nitrate-responsive genes in the transgenic plants were recovered to WT levels, indicating that <italic>ZmNLP6</italic> and <italic>ZmNLP8</italic> can replace the essential roles of the master nitrate regulatory gene <italic>AtNLP7</italic> in nitrate signaling and metabolism. ZmNLP6 and ZmNLP8 are localized in the nucleus and can bind candidate nitrate-responsive <italic>cis</italic>-elements <italic>in vitro</italic>. The biomass and yield of transgenic <italic>Arabidopsis</italic> lines overexpressing <italic>ZmNLP6</italic> and <italic>ZmNLP8</italic> showed significant increase compared with WT and <italic>nlp7-4</italic> mutant line in low nitrate conditions. Thus, <italic>ZmNLP6</italic> and <italic>ZmNLP8</italic> regulate nitrate signaling in transgenic <italic>Arabidopsis</italic> plants and may be potential candidates for improving nitrogen use efficiency of maize.</p>