AUTHOR=Dong Jingping , Xu Jun , Xu Xuewen , Xu Qiang , Chen Xuehao 

TITLE=Inheritance and Quantitative Trait Locus Mapping of Fusarium Wilt Resistance in Cucumber

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01425

DOI=10.3389/fpls.2019.01425

ISSN=1664-462X

ABSTRACT=<p><italic>Fusarium</italic> wilt (FW) is a very serious soil-borne disease worldwide, which usually results in huge yield losses in cucumber production. However, the inheritance and molecular mechanism of the response to FW are still unknown in cucumber (<italic>Cucumis sativus</italic> L.). In this study, two inbred cucumber lines Superina (P<sub>1</sub>) and Rijiecheng (P<sub>2</sub>) were used as the sensitive and resistant lines, respectively. A mixed major gene plus polygene inheritance model was used to analyze the resistance to FW in different generations of cucumber, namely, P<sub>1</sub>, P<sub>2</sub>, F<sub>1</sub> (P<sub>1</sub>×P<sub>2</sub>), B<sub>1</sub>, and B<sub>2</sub>, obtained by backcrossing F<sub>1</sub> plants with Superina (B<sub>1</sub>) or Rijiecheng (B<sub>2</sub>), and F<sub>2</sub>, obtained by self-crossing the F<sub>1</sub> plants. After screening 18 genetic models, we chose the E-1 model, which included two pairs of additive-dominance-epistatic major genes and additive-dominance polygenes, as the optimal model for resistance to FW on the basis of fitness tests. The major effect quantitative trait locus (QTL) <italic>fw2.1</italic> was detected in a 1.91-Mb-long region of chromosome 2 by bulked-segregant analysis. We used five insertion/deletion markers to fine-map the <italic>fw2.1</italic> to a 0.60 Mb interval from 1,248,093 to 1,817,308 bp on chromosome 2 that contained 80 candidate genes. We also used the transcriptome data of Rijiecheng inoculated with <italic>Fusarium oxysporum</italic> f. sp. <italic>cucumerinum</italic> (Foc) to screen the candidate genes. Twelve differentially expressed genes were detected in <italic>fw2.1</italic>, and five of them were significantly induced by FW. The expression levels of the five genes were higher in FW-resistant Rijiecheng inoculated with Foc than in the control inoculated with water. Our results will contribute to a better understanding of the genetic basis of FW resistance in cucumber, which may help in breeding FW-resistant cucumber lines in the future.</p>