Intergeneric hybridization between Diplotaxis siifolia, a wild species and crop brassicas.

Area of Science:

• Plant breeding and genetics
• Crop science
• Horticultural science

Background:

• Intergeneric hybridization is crucial for crop improvement and trait introgression.
• Brassica species are important agricultural crops, but limited by reproductive barriers with wild relatives.
• Diplotaxis siifolia represents a wild relative with potential traits for Brassica improvement.

Purpose of the Study:

• To investigate the feasibility of intergeneric hybridization between Diplotaxis siifolia and Brassica cultivars.
• To overcome pre- and post-fertilization barriers in intergeneric crosses.
• To characterize the resulting hybrids and their amphiploids.

Main Methods:

• Attempted crosses between Diplotaxis siifolia (female) and Brassica cultivars (B. campestris, B. juncea, B. napus).
• Utilized ovary culture to rescue embryos from incompatible crosses.
• In vitro techniques including axillary shoot multiplication and somatic embryogenesis for hybrid propagation.
• Cytological and fertility assessments of F1 hybrids and amphiploids.

Main Results:

• Unilateral incompatibility observed in crosses, with post-fertilization barriers when D. siifolia was the female parent.
• Strong pre-fertilization barriers in reciprocal crosses, preventing pollen tube entry.
• Successful production of intergeneric hybrids (D. siifolia x B. juncea and D. siifolia x B. napus) via ovary culture.
• F1 hybrids were pollen sterile; amphiploids exhibited 60% pollen fertility and produced viable seeds.

Conclusions:

• Ovary culture is an effective method for overcoming reproductive barriers in intergeneric Brassica crosses.
• Amphiploidization can restore fertility and enable seed production in sterile intergeneric hybrids.
• This research opens avenues for introgression of desirable traits from wild Diplotaxis into cultivated Brassica species.