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Noble, OK, United States

Wang Y.,Oklahoma State University | Jha A.K.,Oklahoma State University | Chen R.,Plant Biology Division | Doonan J.H.,John Innes Center | Yang M.,Oklahoma State University
Genesis | Year: 2010

Formation of polyploid organisms by fertilization of unreduced gametes in meiotic mutants is believed to be a common phenomenon in species evolution. However, not well understood is how species in nature generally exist as haploid and diploid organisms in a long evolutionary time while polyploidization must have repeatedly occurred via meiotic mutations. Here, we show that the ploidy increased for two consecutive generations due to unreduced but viable gametes in the Arabidopsis cyclin a1; 2-2 (also named tardy asynchronous meiosis-2)mutant but the resultant octaploid plants produced progeny of either the same or reduced ploidy via genomic reductions during meiosis and pollen mitosis. Ploidy reductions through sexual reproduction were also observed in independently generated artificial octaploid and hexaploid Arabidopsis plants. These results demonstrate that octa-ploid is likely the maximal ploidy produced through sexual reproduction in Arabidopsis. The polyploidy-associated genomic instability may be a general phenomenon that constrains ploidy levels in species evolution. genesis 48: 254-263, 2010. © 2010 Wiley-Liss, Inc.

Xu P.,Plant Biology Division | Wang H.,Plant Biology Division | Coker F.,Plant Biology Division | Ma J.-Y.I.,Plant Biology Division | And 3 more authors.
Molecular Plant-Microbe Interactions | Year: 2012

Cucumber mosaic virus (CMV) associated with D satellite RNA (satRNA) causes lethal systemic necrosis (LSN) in tomato (Solanum lycopersicum), which involves programmed cell death. No resistance to this disease has been found in tomato. We obtained a line of wild tomato, S. habrochaitis, with a homogeneous non-lethal response (NLR) to the infection. This line of S. habrochaitis was crossed with tomato to generate F1 plants that survived the infection with NLR, indicating that NLR is a dominant trait. The NLR trait was successfully passed on to the next generation. The phenotype and genotype segregation was analyzed in the first backcross population. The analyses indicate that the NLR trait is determined by quantitative trait loci (QTL). Major QTL associated with the NLR trait were mapped to chromosomes 5 and 12. Results from Northern blot and in situ hybridization analyses revealed that the F1 and S. habrochaitis plants accumulated minus-strand satRNA more slowly than tomato, and fewer vascular cells were infected. In addition, D satRNA-induced LSN in tomato is correlated with higher accumulation of the minus-strand satRNA compared with the accumulation of the minus strand of a non-necrogenic mutant D satRNA. © 2012 The American Phytopathological Society.

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