Characterizing the genomic basis of weedy rice competitiveness

 

Project Overview

Weeds that infest crop fields are a primary factor limiting global agricultural productivity. Weedy rice (Oryza spp.) invades cultivated rice fields worldwide and stands out for its ability to severely reduce yields  in the crop that serves as the primary calorie source for nearly half the world’s population. Weedy rice has been shown by us and others to have evolved independently multiple times, in most cases through ‘de-domestication’ (feralization) from cultivated rice. With each origin, weedy rice has evolved competitive abilities that allow it to aggressively invade rice fields, reduce yields, and contaminate harvests. Our long-term goal is to determine how weedy rice has evolved its competitiveness traits, and to identify loci that can be exploited for weed control or crop improvement. Here we propose to characterize three key features of weedy rice growth and reproduction that allow it to so successfully outcompete its domesticated relatives. Using this genomic model species, we will establish the evolutionary and genomic bases of weed competitiveness traits in the following three specific aims:

1.     Determine the genetic basis of the root system architecture (RSA), which we have recently shown to have evolved convergently with repeated origins of weedy rice, and establish the connection between weedy rice RSA and weed competition via differential nutrient uptake.  

2.     Identify the genetic basis of seed shattering in independently evolved populations of weedy rice, and establish the mechanisms underlying the evolutionary lability of this trait.

3.     Determine the genetic and biochemical bases underlying the differential resilience of US weedy rice to rice blast disease, a major fungal pathogen of rice.