Isolation and characterization of high temperature-resistant germination mutants of Arabidopsis thaliana.

Noriko Tamura, Takahiro Yoshida, Arata Tanaka, Ryuta Sasaki, Asuka Bando, Shigeo Toh, Loïc Lepiniec, Naoto Kawakami

Laboratory of Plant Molecular Physiology, Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki 214-8571, Japan.

Plant & cell physiology 2006 Aug

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Temperature is a primary environmental cue for seed germination of many weeds and vegetables. To investigate the mechanism of germination regulation by temperature, we selected five high temperature (thermoinhibition)-resistant germination mutants (TRW lines) from 20,000 T-DNA insertion lines of Arabidopsis. Segregation analyses indicated that each of the five lines had single locus recessive mutations. The seeds of TRW134-15 and TRW187 showed reduced sensitivity to ABA and also to the gibberrellin biosynthesis inhibitor, paclobutrazol. Genetic and nucleotide sequencing analyses indicated that TRW187 is a new allele of abi3 (abi3-14). TRW71-1 exhibited a maternal effect for both thermoinhibition-resistant and transparent testa phenotypes, and genetic analysis revealed that the mutation was allelic to tt7 (tt7-4 sib). Interestingly, the seeds of reduced dormancy mutants rdo1, rdo2, rdo3 and rdo4 were also thermoinhibition tolerant, and all the TRW seeds showed reduced dormancy. Like rdo3, TRW13-1 had shorter siliques and slightly shorter stems than the wild type. The mutation of TRW13-1 was mapped to the bottom arm of chromosome 1 where rdo3 has also been mapped, but the two mutants are not allelic. We designated TRW13-1 as thermoinhibition-resistant germination 1 (trg1). We also mapped the ABA-insensitive mutation of TRW134-15 to the bottom arm of chromosome 5 and named it trg2. These results show that both embryo/endosperm and maternal factors contribute to germination inhibition at supraoptimal temperatures in Arabidopsis. In addition, we confirm the role of ABA in thermoinhibition of seed germination and a link between seed physiological dormancy and response to high temperature.

Citation

Noriko Tamura, Takahiro Yoshida, Arata Tanaka, Ryuta Sasaki, Asuka Bando, Shigeo Toh, Loïc Lepiniec, Naoto Kawakami. Isolation and characterization of high temperature-resistant germination mutants of Arabidopsis thaliana. Plant & cell physiology. 2006 Aug;47(8):1081-94