Comparative microscopic and molecular analysis of Thatcher near‐isogenic lines with wheat leaf rust resistance genes Lr2a, Lr3, LrB or Lr9 upon challenge with different Puccinia triticina races. (16th July 2012)

• Record Type: Journal Article
• Authors: Wang, X.; McCallum, B. D.; Fetch, T.; Bakkeren, G.; Marais, G. F.; Saville, B. J.
• Is Part Of: Plant pathology. Volume 62:Number 3(2013:Jun.)
• Page Start: 698
• Page End: 707
• Publication Date: 2012-07-16
• Subjects: Agricultural pests -- Periodicals; Plant diseases -- Periodicals; 632
• DOI: 10.1111/j.1365-3059.2012.02660.x
• Languages: English
• ISSNs: 0032-0862

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Thatcher near‐isogenic lines (NILs) of wheat carrying resistance gene <italic>Lr2a</italic>, <italic>Lr3</italic>, <italic>LrB</italic> or <italic>Lr9</italic> were inoculated with <italic>Puccinia triticina</italic> races of virulence phenotype BBBD, MBDS, SBDG and FBDJ. <italic>Puccinia triticina</italic> infection structures were analysed under the fluorescence microscope over a course of 14 days after inoculation (dai). The relative proportion of <italic>P. triticina</italic> and wheat genomic DNA in infected leaves was estimated with a semiquantitative multiplex PCR analysis using <italic>P. triticina</italic>‐ and wheat‐specific primers. The occurrence of a hypersensitive response (HR), cellular lignification and callose deposition in inoculated plants was investigated microscopically. In interactions producing highly resistant infection type (IT) '0;', a maximum of two haustorial mother cells per infection site were produced, and there was no increase in the proportion of <italic>P. triticina</italic> genomic DNA in infected leaves, indicating the absence of <italic>P. triticina</italic> growth. In comparison, sizes of <italic>P. triticina</italic> colonies increased gradually in interactions producing moderately resistant IT '1' and '2', with the highest proportion of <italic>P. triticina</italic> genomic DNA found in leaves sampled at 14 dai. In interactions producing susceptible IT '3–4', the highest proportion of <italic>P. triticina</italic> genomic DNA was found in leaves sampled at 10 dai (45·5–51·5%). HR and cellular lignification were induced in interactions producing IT '0;' and '1' at 1 dai but they were not observed in interactions producing IT '2' until 2 dai. No HR or cellular lignification were induced in interactions producing susceptible IT '3–4'. Furthermore, a strong deposition of callose was induced in <italic>Lr9 </italic>+<italic> </italic>BBBD and <italic>Lr9 </italic>+<italic> </italic>FBDJ (IT '0;'), whereas this defence response was not induced in resistant or susceptible interactions involving <italic>Lr2a</italic>, <italic>Lr3</italic> or <italic>LrB, </italic> indicating that <italic>Lr9</italic> mediated resistance was different from that conditioned by <italic>Lr2a</italic>, <italic>Lr3</italic> or <italic>LrB</italic>.</p> </abstract>