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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #353696
Title: Construction of high-density genetic maps and detection of QTLs associated with huanglongbing tolerance in citrus

Author
item HUANG, MING - University Of Florida
item ROOSE, MIKEAL - University Of California
item YU, QIBIN - University Of Florida
item DU, DONGLIANG - University Of Florida
item ZHANG, YI - University Of Florida
item DENG, ZHANAO - University Of Florida
item IREY, MICHAEL - Us Sugar Corporation
item Stover, Eddie
item GMITTER, FREDERICK - University Of Florida

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2018
Publication Date: 11/27/2018
Citation: Huang, M., Roose, M., Yu, Q., Du, D., Yuan, Y., Zhang, Y., Deng, Z., Stover, E., Gmitter, F. 2018. Construction of high-density genetic maps and detection of QTLs associated with huanglongbing tolerance in citrus. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2018.01694.
DOI: https://doi.org/10.3389/fpls.2018.01694

Interpretive Summary: No true resistance to Huanglongbing (HLB), a serious citrus disease, is found within commercial citrus cultivars, though trifoliate orange has been described as resistant or tolerant. A replicated population of trifoliate orange, sweet orange, and their hybrids were exposed to intense HLB pressure for two years followed by data collection for a subsequent three years, for a total of ten time points. As expected the levels of the HLB pathogen where high in sweet oranges, low in trifoliate orange, and intermediate in their hybrids. The hybrids showed apparent differences between different lines. Genetic maps constructed separately for trifoliate orange and sweet orange were used to see if gene markers were associated with apparent HLB resistance, and several strong associations were found. This information should be useful for citrus breeding to support long-term control of this devastating disease.

Technical Abstract: No true resistance to Huanglongbing (HLB), a citrus disease associated with infection of Candidatus Liberibacter asiaticus (CLas), is found within commercial citrus cultivars, though trifoliate orange (Poncirus trifoliata) has been described as resistant or tolerant. Through genotyping an intergeneric F1 population by Genotyping-by-Sequencing, high-density SNP-based genetic maps were constructed separately for trifoliate orange and sweet orange (Citrus sinensis). Both genetic maps exhibited high synteny and high coverage of citrus genome. After exposure to intense HLB pressure for two years, cycle threshold (Ct) value of quantitative polymerase chain reaction (qPCR) for CLas detection in leaves throughout ten time points during the next three years was above 35 in trifoliate oranges, under 28 in sweet oranges, and ranged from 24 to 38 and exhibited obvious segregation among progenies. Phenotypic data of percentage of healthy trees showed high correlation with the Ct value. By mapping the two traits at all time points, a total of nine clusters of quantitative trait loci or locus (QTLs) were detected, of which five, respectively located on LG-t7 and LG-t8 of trifoliate orange map and LG-s3, LG-s5 and LG-s9 of sweet orange map, collectively explained a major part of the phenotypic variation. This study provides a starting point for citrus breeding to support long-term control of this devastating disease.