Interspecific hybridization between Camelina sativa and C. microcarpa

A common source of genetic variation to improve crops are wild relatives. Mark Tepfer and colleagues from AgroParisTech have been looking at Camelina sativa which may become an oilseed crop. While the prospects look good, with the quantity of omega-3 oils offering the possibility of replacing fish as a source. But there still work still needs to be done to develop a commercial crop. 

“Camelina has been a neglected crop for the past century, the available cultivars have not undergone extensive improvement using modern plant breeding strategies. In recent years, several laboratories have presented evidence suggesting that the genetic diversity present in current cultivars is relatively narrow…, which greatly diminishes the prospects for crop improvement,” write Tepfer and colleagues. So they looked to see if the genes they needed could be found in a wild relative, C. microcarpa.

The attraction of C. microcarpa is that it has a similar genome structure to C. sativa, with an allohexaploid genome. Tepfer and colleagues refer to recent work showing that the two species have the same chromosome organisation, and another paper suggesting C. microcarpa may be the parent species of C. sativa.

So to test if C. microcarpa could be a suitable source of genetic material, the team created  C. sativa × C. microcarpa hybrids.

“We observed that the F₁ hybrids, unremarkably, displayed a morphological phenotype intermediate between that of the two parental species during the vegetative phase, and the lipid composition of the F₁ seeds was equivalent to that of the parents,” write the scientists, but the hybrids had problems.

“We also observed that F₁C. microcarpa × C. sativa hybrids showed very reduced fertility. This is very likely due to the frequent and diverse meiotic abnormalities we observed in these plants, in particular the presence of univalents, bridges and fragments in many cells.”

Despite this they were able to produce some F₂ plants. Nevertheless, the abnormalities make backcrossing with C. sativa difficult, say the authors.

“Altogether our results demonstrate that C. sativa and C. microcarpa may be less related to one another than previously thought, or that there is a great diversity of genome structure within C. microcarpa. In terms of pre-breeding (gene introgression from C. microcarpa into cultivated camelina), our results suggest that, at least for C. microcarpa genotypes similar to those studied here, this would not be a project to be engaged in lightly.”