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Increased ABA sensitivity results in higher seed dormancy in soft white spring wheat cultivar ‘Zak’

Affiliation

  • 1 Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, USA.
  • PMID: 23212773
  • PMCID: PMC4241963
  • DOI: 10.1007/s00122-012-2018-0

Free PMC article

Increased ABA sensitivity results in higher seed dormancy in soft white spring wheat cultivar ‘Zak’

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Authors

Affiliation

  • 1 Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, USA.
  • PMID: 23212773
  • PMCID: PMC4241963
  • DOI: 10.1007/s00122-012-2018-0

Abstract

As a strategy to increase the seed dormancy of soft white wheat, mutants with increased sensitivity to the plant hormone abscisic acid (ABA) were identified in mutagenized grain of soft white spring wheat “Zak”. Lack of seed dormancy is correlated with increased susceptibility to preharvest sprouting in wheat, especially those cultivars with white kernels. ABA induces seed dormancy during embryo maturation and inhibits the germination of mature grain. Three mutant lines called Zak ERA8, Zak ERA19A, and Zak ERA19B (Zak ENHANCED RESPONSE to ABA) were recovered based on failure to germinate on 5 μM ABA. All three mutants resulted in increased ABA sensitivity over a wide range of concentrations such that a phenotype can be detected at very low ABA concentrations. Wheat loses sensitivity to ABA inhibition of germination with extended periods of dry after-ripening. All three mutants recovered required more time to after-ripen sufficiently to germinate in the absence of ABA and to lose sensitivity to 5 μM ABA. However, an increase in ABA sensitivity could be detected after as long as 3 years of after-ripening using high ABA concentrations. The Zak ERA8 line showed the strongest phenotype and segregated as a single semi-dominant mutation. This mutation resulted in no obvious decrease in yield and is a good candidate gene for breeding preharvest sprouting tolerance.

Figures

Germination index (GI) over a…

Germination index (GI) over a 14-week after-ripening time course for Chinese Spring (…

ABA dose response in germination…

ABA dose response in germination of Zak ERA8, 19A, and 19B compared to…

Germination index (GI) of intact…

Germination index (GI) of intact M 5 seeds of Zak ERA8 and Zak…

Segregation analysis of Zak ERA8…

Segregation analysis of Zak ERA8 and comparison of F 2 and F 3…

Germination index (GI) of Zak…

Germination index (GI) of Zak ERA mutants and wild type over an after-ripening…

As a strategy to increase the seed dormancy of soft white wheat, mutants with increased sensitivity to the plant hormone abscisic acid (ABA) were identified in mutagenized grain of soft white spring wheat "Zak". Lack of seed dormancy is correlated with increased susceptibility to preharvest sproutin …

Higher seed is no guarantee of first-round success

So your team has the home-ice advantage in the first round of the playoffs. Does that really make a difference?

The short answer: Yes. The long answer: Maybe not as much as you’d think.

This is the 17th year the National Hockey League has used the current format of having the top eight teams in each conference qualify for the playoffs. Never in the first 16 have all eight higher-seeded teams advanced to the second round.

Nor is a top seed a guarantee of moving on. The 32 No. 1 seeds since 1994 have advanced 23 times, a .719 percentage that sounds impressive until you consider that that the 1-8 pairings match the best and worst teams in the conference — the average differential between the first and last qualifiers is just under 23 points in the Eastern Conference and 28 points in the West.

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In contrast, the National Basketball Association, which uses the same playoff format, has had only two top-seeded teams — Miami in 1999 and Dallas in 2006 — knocked out in the opening round in the last 16 years.

And here’s a word of warning for the Vancouver Canucks, who celebrated their first Presidents’ Trophy before playing their final home game: The regular-season champion hasn’t made it past the first round since 2008. Both the 2009 San Jose Sharks and the 2010 Washington Capitals lost in the conference quarterfinals — the Sharks to Anaheim, a team they eclipsed by 26 points during the regular season; the Caps to Montreal, which finished 33 points behind Washington last season.

In all, four of the last 10 regular-season champions haven’t made it through the first round.

But if finishing first is no guarantee of winning, being the second seed in the opening round is downright dangerous. Just 17 of the 32 No. 2 seeds under the current format have gotten out of the opening round, the worst showing of any seed. However, second-seeded teams have been improved — last year’s first-round loss by New Jersey to Philadelphia was the first by a second-seeded team since 2006.

No. 3 seeds have done better, going 20-12 since 1994. But the trend for third-seeded teams is the opposite of second-seeded clubs: In the past five years, No. 3 seeds have lost six of 10 series, including the last four in the Eastern Conference.

Perhaps surprisingly, No. 4 seeds are almost as successful in the opening round as top seeds — even though fourth-seeded teams are playing teams much closer to their success rate. Fourth seeds have won 22 of the 32 series against fifth seeds, just one less than No. 1-seeded teams have won against eighth-seeded teams.

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