Strategies for isolating mutants in Hieracium with dysfunctional apomixis

Area of Science:

• Plant genetics
• Reproductive biology
• Molecular biology

Background:

• Species in Hieracium subgenus Pilosella exhibit apospory, a form of asexual seed production.
• The capacity for apomixis is inherited as a dominant trait, controlled by a single locus.
• Modifier loci influence the expression level of apomixis.

Purpose of the Study:

• To identify and test sequences involved in controlling apomixis in Hieracium.
• To understand the genetic mechanisms underlying asexual seed formation.

Main Methods:

• Utilizing an enhancer trap element based on maize Activator/Dissociator (Ac/Ds) transposons with a β-glucuronidase reporter.
• Inducing mutations through gamma irradiation of seeds and T-DNA-mediated mutagenesis.
• Analyzing mutants for changes in apomixis and sexuality.

Main Results:

• 69 stable mutants were isolated after gamma irradiation, currently undergoing analysis.
• Two mutants from Agrobacterium-mediated transformation experiments lost apomixis but retained sexuality.
• One mutant failed to form aposporous initials, while the other showed initial differentiation without division, with observed compensatory sexuality.

Conclusions:

• Genetic manipulation and mutagenesis strategies are effective in studying apomixis control in Hieracium.
• Specific mutations can disrupt apospory, leading to loss of asexual seed formation.
• The study provides insights into the genetic regulation of apomixis and its relationship with sexuality.