Development of resistant cultivars is the main control measure against sugarcane brown rust caused by Puccinia melanocephala. Durability is uncertain, since the pathogen possesses adaptive ability to overcome host plant resistance. A differential gene expression study utilizing suppressive subtraction hybridization was conducted to improve understanding of brown rust resistance mechanisms in sugarcane. The expression patterns of 11 unigenes representing biosynthetic pathways, defense-related genes, and signaling genes were analyzed in L 99-233, a cultivar exhibiting quantitative resistance, L 01-299, a resistant cultivar with the major resistance gene Bru1, and two susceptible cultivars, Ho 95-988 and L 09-125, at 24 h, 48 h, 72 h, and 1 week after inoculation with P. melanocephala using (semi)quantitative RT-PCR. All genes analyzed for their expression showed message accumulation upon infection in susceptible and resistant cultivars, but the maintenance of high amounts of mRNAs of the genes for a prolonged time period appeared to be the most important factor contributing to brown rust resistance. Differences in the time-course of gene expression were detected between L 01-299 and L 99-233 suggesting variable mechanisms for resistance between the cultivars. Molecular markers were used to screen the World Collection of Sugarcane and Related Grasses (WCSRG) for Bru1 to determine its distribution and frequency in Saccharum species and related genera. A total of 1,282 clones were screened. Bru1 was distributed across the Saccharum complex, but the frequency varied among species. Bru1was more prevalent in S. robustum clones (59.1%), whereas it occurred in low frequency and exhibited the highest level of variability in clones of S. spontaneum (18.8%). Bru1 frequency was highest in the two secondary cultivated species, S. barberi (79.3%) and S. sinense (71.8%). The frequency of Bru1 detection was 26.4% and 21.0% for S. officinarum and interspecific hybrid clones, respectively. The characterization of the WCSRG for Bru1 distribution and prevalence will complement efforts to characterize diversity in the Saccharum complex for the expected expanded use of marker-assisted selection in the future. Selection for quantitative resistance in combination with Bru1 could allow breeding programs to develop sugarcane cultivars with effective and durable resistance against brown rust.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-04112016-135419 |
| Date | 12 May 2016 |
| Creators | Avellaneda Barbosa, Mavir Carolina |
| Contributors | Hoy, Jeffrey W., Baisakh, Niranjan, Datnoff, Lawrence, Reagan, Thomas E. |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-04112016-135419/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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