Weed evolution: Genetic differentiation among wild, weedy, and crop radish

Area of Science:

• Evolutionary biology
• Plant sciences
• Agricultural ecology

Background:

• Few weed species cause significant crop losses, suggesting limited evolutionary paths to weediness.
• Agricultural weeds can originate from escaped crops, wild species, or crop-wild hybrids.

Purpose of the Study:

• To investigate the evolutionary origins of weedy radish (Raphanus raphanistrum).
• To determine if weedy radish is an escaped crop, a wild species, or a hybrid.
• To assess adaptation of weedy radish to agricultural environments, focusing on flowering time.

Main Methods:

• Genetic analysis using 21 CAPS and SSR markers on 338 individuals from 34 Raphanus populations.
• Common garden experiments with over 2,400 individuals from 43 populations to estimate genetic differentiation in flowering time.

Main Results:

• Weedy radish (R. r. raphanistrum) is genetically most similar to native populations of R. r. raphanistrum.
• Evidence does not support weedy radish originating as a feral crop or crop hybrid.
• Weedy radish exhibits significantly faster flowering times compared to other Raphanus populations and cultivars.

Conclusions:

• The origin of weedy radish is likely from wild Raphanus populations.
• Rapid flowering in weedy radish suggests strong adaptation to the disturbed conditions of agricultural fields.