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Plant Height Affects Fusarium Crown Rot Severity in Wheat

First, second, third, tenth, and eleventh authors: CSIRO Plant Industry, 306 Carmody Road, St. Lucia, QLD 4067, Australia; first, fourth, and fifth authors: Triticeae Research Institute, Sichuan Agricultural University, Yaan 625014, China; second, sixth, and seventh authors: Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; third and eighth authors: School of Plant Biology, The University of Western Australia, Perth, WA 6009, Australia; and ninth author: Centre for Applications in Natural Resource Mathematics, School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.

Effects of plant height on Fusarium crown rot (FCR) disease severity were investigated using 12 pairs of near-isogenic lines (NILs) for six different reduced height (Rht) genes in wheat. The dwarf isolines all gave better FCR resistance when compared with their respective tall counterparts, although the Rht genes involved in these NILs are located on several different chromosomes. Treating plants with exogenous gibberellin increased FCR severity as well as seedling lengths in all of the isolines tested. Analysis of the expression of several defense genes with known correlation with resistance to FCR pathogens between the Rht isolines following FCR inoculation indicated that the better resistance of the dwarf isolines was not due to enhanced defense gene induction. These results suggested that the difference in FCR severity between the tall and dwarf isolines is likely due to their height difference per se or to some physiological and structural consequences of reduced height. Thus, caution should be taken when considering to exploit any FCR locus located near a height gene.

Additional keywords: Fusarium pseudograminearum.