Abstract Detail

Darwins' reversals: What we now know about Feralization and Crop Wild Relatives

Caicedo, Ana [1], Li, Xiang [2].

Learning to let go: the evolution of seed shattering in de-domesticated populations of weedy rice.

The invention of agriculture by humans gave rise to a novel and dynamic environment, subsequently exploited by opportunistic weedy plants. These agricultural weeds are currently one of the largest constraints on crop productivity, and are constantly evolving in response to human selective pressure. Weedy or red rice (Oryza spp.) is one such weed — a conspecific weed of cultivated rice (O. sativa) that infests rice fields worldwide, aggressively competing with the crop and decreasing yields. Multiple recent studies have shown that weedy rice has evolved many times independently from a variety of ancestral backgrounds. However, most weedy rice origins have been through de-domestication of cultivated rice varieties. In all populations, weedy rice has evolved the capacity to shatter its seeds, a mechanism that aids in efficient seed dispersal and helps in adaptation to the agricultural environment. The shattering trait is not present in cultivated rice ancestors, due to strong selection during domestication to facilitate seed harvesting. This prompts fundamental questions about how weedy rice groups have reacquired the shattering trait throughout the de-domestication process. We are dissecting the cellular and genetic basis of the seed shattering trait in three independently evolved populations of weedy rice. Preliminary mapping in weed x crop crosses suggests that different genetic mechanisms underlie the shattering trait across weed populations, indicating that convergence in seed shattering at the phenotypic level is not due to convergence at the genetic level. Seed shattering is dependent on the development of a functional abscission zone (AZ), a layer of densely cytoplasmic and non-lignified cells, at the base of the flower where it attaches to the pedicel. Our morphological analyses suggest that the ancestral state of the AZ differs among weedy rice domesticated ancestors, but converges among weedy rice groups. The diversity of evolutionary paths leading to largely equivalent weedy rice populations, and the number of times de-domestication of cultivated rice has occurred, raises important questions about the evolutionary lability of this important food crop.

1 - University Of Massachusetts, Biology, 221 Morrill Science Center, 611 North Pleasant St., Amherst, MA, 01003, United States
2 - N 426 Life Science Laboratories , 240 Thatcher Way, Amherst , MA, 01003, United States

Keywords:
de-domestication
weed evolution.

Presentation Type: Colloquium Presentations
Session: C03, Darwins' reversals: What we now know about Feralization and Crop Wild Relatives
Location: /
Date: Tuesday, July 20th, 2021
Time: 11:00 AM(EDT)
Number: C03005
Abstract ID:517
Candidate for Awards:None