AUTHOR=Huang Qiulan , Li Lin , Zheng Minghui , Chen Fang , Long Hai , Deng Guangbing , Pan Zhifen , Liang Junjun , Li Qiao , Yu Maoqun , Zhang Haili 

TITLE=The Tryptophan decarboxylase 1 Gene From Aegilops variabilis No.1 Regulate the Resistance Against Cereal Cyst Nematode by Altering the Downstream Secondary Metabolite Contents Rather Than Auxin Synthesis

JOURNAL=Frontiers in Plant Science

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01297

DOI=10.3389/fpls.2018.01297

ISSN=1664-462X

ABSTRACT=<p>Cereal cyst nematode (CCN, <italic>Heterodera avenae</italic>) is a most important pathogen of wheat and causes tremendous yield loss annually over the world. Since the lack of resistance materials among wheat cultivars, identification and characterization of the resistance-related genes from the relatives of wheat is a necessary and efficient way. As a close relative of wheat with high resistance against CCN, <italic>Aegilops variabilis No.1</italic> is believed to be a valuable source for wheat breeding against this devastating disease. However so far, very few resistance-associated genes have been characterized from this species. In this study, we present that the <italic>tryptophan decarboxylase</italic> genes from <italic>Ae. variabilis No.1</italic> (<italic>AeVTDC1</italic> and <italic>AeVTDC2</italic>) were both induced by CCN juveniles at the early stage of resistance response (30 h post-inoculation), with <italic>AeVTDC1</italic> more sensitive to CCN infection than <italic>AeVTDC2</italic>. Silencing of <italic>AeVTDC1</italic> led to compromised immunity to CCN with more CCN intrusion into roots; while overexpression <italic>AeVTDC1</italic> in <italic>Nicotiana tabacum</italic> dramatically enhanced the resistance of plants by reducing the knots formed on roots. Metabolism analysis showed that the contents of secondary metabolites with activity of resistance to varied pathogens correlated with the expression level of <italic>AeVTDC1</italic> in both <italic>Ae. variabilis No.1</italic> and the transgenic tobacco plants. In addition, the content of IAA was not affected by either silencing or overexpressing of <italic>AeVTDC1</italic>. Hence, our research provided <italic>AeVTDC1</italic> a valuable target that mediates resistance to CCN and root knot nematode (RKN, <italic>Meloidogyne naasi</italic>) without influencing the auxin biosynthesis.</p>