NO-mediated dormancy release of Avena fatua caryopses is associated with decrease in abscisic acid sensitivity,...

Area of Science:

• Plant Physiology
• Seed Biology
• Biochemistry

Background:

• Seed dormancy is a critical factor regulating plant life cycles and crop establishment.
• Abscisic acid (ABA) and gibberellins (GAs) are key hormonal regulators of seed dormancy and germination.
• The role of nitric oxide (NO) in seed dormancy, particularly in wild oat (Avena fatua), requires further elucidation.

Purpose of the Study:

• To investigate the role of nitric oxide (NO) in releasing seed dormancy in Avena fatua.
• To explore the interaction between NO, abscisic acid (ABA), and gibberellins (GAs) in regulating dormancy.
• To understand the influence of NO on seed dormancy levels and germination sensitivity to hormones.

Main Methods:

• Application of various nitric oxide (NO) donors (SNP, GSNO, acidified KNO2) to dormant and after-ripened Avena fatua caryopses.
• Measurement of endogenous ABA and bioactive GAs (GA4, GA7, GA1, GA3, GA6) levels.
• Assessment of caryopsis sensitivity to exogenous ABA and the effect of GA biosynthesis inhibitor (PAC) and reactive oxygen species (ROS) scavengers.

Main Results:

• Nitric oxide (NO) effectively released primary dormancy in Avena fatua caryopses, with the effect dependent on the initial dormancy level.
• NO decreased caryopsis sensitivity to ABA and lowered the ABA to GA ratio by reducing ABA levels without affecting GA levels.
• NO's dormancy-releasing effect was counteracted by a GA biosynthesis inhibitor (PAC) and reduced by ROS scavengers.

Conclusions:

• Nitric oxide (NO) plays a significant role in breaking seed dormancy in Avena fatua.
• The NO-mediated dormancy release involves modulation of ABA sensitivity and the ABA/GA balance.
• This study provides novel insights into the hormonal crosstalk regulating seed dormancy, highlighting NO's involvement.