Research collaboration on illegitimate pollination and lateral gene transfer in grasses

Overview

This research investigates the mechanism behind lateral gene transfer (LGT) in grasses, specifically testing whether illegitimate pollination—the growth of pollen tubes from one species on the stigma of another—provides a route for DNA to move between grass species. The work addresses a fundamental gap in understanding how genes cross species boundaries in grasses, a phenomenon that has been demonstrated through comparative genomics but whose biological mechanism remains unclear. The findings have implications for crop genetics, evolutionary biology, and our understanding of gene flow in wind-pollinated species, including major agricultural crops.

Technical specifications

Research approach:

• Quantifies heterospecific pollen tube growth on the stigma of Zea mays (maize), an out-crossing species with 11 known LGT events
• Tests pollen from five known LGT donor species and five control species, both individually and mixed with maize pollen
• Monitors pollen tube growth and harvests resulting seeds
• Uses PCR amplification of species-specific repetitive DNA sequences in pooled genomic DNA from seedlings to detect foreign DNA
• Builds on prior demonstrations that pollen tubes can grow in distant grass crosses (e.g., wheat × maize and oat × maize), producing partial hybrids that sometimes retain and transmit heterospecific DNA

Key scientific premise:

• Wind pollination is universal in grasses, making illegitimate pollination a plausible mechanism for placing exogenous DNA directly in the germline
• Out-crossing species show the highest rates of LGT, suggesting mating systems influence gene transfer
• The co-existence of native and alien chromosomes during early hybrid development creates conditions favorable for LGT

Technology readiness level

This is an active fundamental research program at the hypothesis-testing stage. The underlying observation that LGT occurs among grasses is well-established through prior comparative genomics work recognized by the 2021 IAPT Stebbins Medal. Prior laboratory crosses have demonstrated that heterospecific pollen tubes can grow and produce partial hybrids in controlled conditions. The current validation phase involves systematic experimental testing of specific predictions about pollen tube growth rates and DNA incorporation frequencies. The research is positioned to generate mechanistic insights into LGT rather than deliver an immediately deployable technology or product.