Gene Flow from Herbicide-Resistant Crops to Wild Relatives

Abstract

Development of herbicide-resistant (HR) crops is way to overcome problems in weed control due to weed resistance to herbicides and absence of new herbicides with a new mode of action for their control. Three types of HR crops were developed: nontransgenic, transgenic, and multiple HR crops. Cultivation of HR crops is associated not only with many benefits (simplification of weed control, more effective and efficient weed control, higher yields, etc.) but also with various risks (development of HR weeds, development of HR volunteer crops, gene flow from HR crops to susceptible relatives, etc.). The greatest risk is gene flow from HR crops to related weed species, wild relatives or conventional crops of the same species. Unwanted gene flow could be prevented or reduced using different barriers such as isolation in space or time, protective vegetation barriers, male sterility, etc. Sunflower hybrids resistant to herbicides (imidazolinones and sulfonilureas) was developed by conventional breeding methods, and their introduction in Serbian fields has enabled a more efficient control of harmful weed species, but the presence of huge populations of weedy sunflower is the main concern associated with their cultivation, because numerous studies have confirmed gene flow from sunflower to its relatives.

Theoretical assessment of persistence and adaptation in weeds with complex life cycles

“…Besides standing genetic variation and de novo mutations, resistance can also arise from pollen-mediated gene flow from neighbouring resistant populations, the introduction of herbicide resistant rhizomes and seeds via contaminated equipment or gene flow from closely related resistant crops (Vrbničanin et al 2017, Beckie et al 2019). Maxwell et al (1990) included gene flow from pollen and seed immigration in their population model of annual weeds.…”

Pollen‐mediated flow of herbicide resistance genes in Beckmannia syzigachne

“…As resistant B. syzigachne has become increasingly problematic in the middle and lower Yangtze River basin, every effort should be made to prevent the spread of resistant B. syzigachne populations. For a long time, maintaining isolation distance has been used as a measure to reduce undesirable gene flow in plant breeding programs 46 . Once a resistant B. syzigachne population is suspected in the field, the B. syzigachne at the edge of the field need to be removed before flowering.…”

“…For a long time, maintaining isolation distance has been used as a measure to reduce undesirable gene flow in plant breeding programs. 46 Once a resistant B. syzigachne population is suspected in the field, the B. syzigachne at the edge of the field need to be removed before flowering. At the same time, we need to block and eliminate the seeds of B. syzigachne that have occurred in the field.…”

The recent possible strategies for breeding ultraviolet-B-resistant crops

“…It is important to put strategies like monitoring and containment measures into practice to lessen these risks. Biosafety concerns are also raised by the potential for gene flow to wild relatives and the emergence of “superweeds” that are difficult to control [ 103 ]. These factors call for careful research and the adoption of preventive measures.…”