Sunflower transcription factors in abiotic stress responses as tools to improve performance of different crops

RAINERI, JESICA; MARÍA OTEGUI; CABELLO, JULIETA V; RAQUEL L. CHAN; RIBICHICH, KARINA F

Congreso; Sunflower and Climate Change. Touluse; 2018

Sunflower was reported as a crop tolerant to drought conditions; this and other abiotic stress responses are regulated at different levels involving diverse biomolecules. Among these molecules, transcription factors (TFs) play key roles in early steps. These proteins are more abundant in the plant kingdom than in animals and other kingdoms, suggesting that the transcriptional process is the major step in the regulation of gene expression in plants. When compared to model plants, sunflower has a remarkably number of divergent TFs belonging to different families. With the hypothesis that, at least in part, such divergent TFs could be responsible of the sunflower adaptation capability, we decided to perform functional genomics with selected TFs belonging to the homeodomain-leucine zipper (HD-Zip) subfamily I, unique to plants. Members of HD-Zip I subfamily were assigned roles in the plant response to abiotic and biotic stresses.HaHB4 and HaHB11, both sunflower divergent HD-Zip I TFs, were firstly introduced in Arabidopsis as transgenes driven either by the 35S CaMV promoter or their own inducible promoters. HaHB4 and HaHB11 conferred drought and salinity tolerance without yield penalty under such stresses, whereas transgenic HaHB11 Arabidopsis also exhibited improved performance under flooding stress, including waterlogging and submergence situations as well as enhanced yield in standard growth conditions.HaHB4 was used to transform soybean and wheat, and both crops showed improved yield across contrasting environments in field trials. Transgenic HaHB4 soybean was recently approved by regulatory organisms both in Argentina and the US and will probably be a commercial product during 2018, becoming the first transgenic crop in which the gene donor is another plant.HaHB11 was introduced in maize and rice. Transgenic maize plants were assessed both in the greenhouse and in the field. Current results indicate that HaHB11 transgenic maize plants exhibit some of the traits observed in Arabidopsis but at different extents.The morphological and architectural observation of transgenic plants bearing HaHB4 and HaHB11 indicated that stem width and vascular bundles anatomy are major traits determining seed yield. This observation was corroborated by applying weight to sunflower seedlings in early developmental stages. The obtained results were in agreement with observations performed in field trials by other research groups.We can conclude that sunflower TFs can be considered as biotechnological tools to improve other crops but also to recover seed yield progress in this species.