Peculiarities of the Transformation of Asteraceae Family Species: The Cases of Sunflower and Lettuce

Abstract

The Asteraceae family is the largest and most diversified family of the Angiosperms, characterized by the presence of numerous clustered inflorescences, which have the appearance of a single compound flower. It is estimated that this family represents around 10% of all flowered species, with a great biodiversity, covering all environments on the planet, except Antarctica. Also, it includes economically important crops, such as lettuce, sunflower, and chrysanthemum; wild flowers; herbs, and several species that produce molecules with pharmacological properties. Nevertheless, the biotechnological improvement of this family is limited to a few species and their genetic transformation was achieved later than in other plant families. Lettuce (Lactuca sativa L.) is a model species in molecular biology and plant biotechnology that has easily adapted to tissue culture, with efficient shoot regeneration from different tissues, organs, cells, and protoplasts. Due to this plasticity, it was possible to obtain transgenic plants tolerant to biotic or abiotic stresses as well as for the production of commercially interesting molecules (molecular farming). These advances, together with the complete sequencing of lettuce genome allowed the rapid adoption of gene editing using the CRISPR system. On the other hand, sunflower (Helianthus annuus L.) is a species that for years was considered recalcitrant to in vitro culture. Although this difficulty was overcome and some publications were made on sunflower genetic transformation, until now there is no transgenic variety commercialized or authorized for cultivation. In this article, we review similarities (such as avoiding the utilization of the CaMV35S promoter in transformation vectors) and differences (such as transformation efficiency) in the state of the art of genetic transformation techniques performed in these two species.

Up-to-Date Overview of the Use of Natural Ingredients in Sunscreens

“…The Asteraceae family is one of the largest angiosperm families and the plants are characterized by the presence of numerous clustered inflorescences, which have the appearance of a single compound flower. It is estimated that this family represents around 10% of all flowered species, with a great biodiversity, covering all environments on the planet, except Antarctica [ 41 ].…”

Accelerated Breeding for Helianthus annuus (Sunflower) through Doubled Haploidy: An Insight on Past and Future Prospects in the Era of Genome Editing

“…Agrobacterium tumefaciens -mediated transformation remains the method of choice in plant gene editing experiments, but transformation of sunflower remains a challenge with efficiencies of 1–4% [ 14 , 90 , 91 ]. Sunflower is associated with a host of transformation limitations, including low A. tumefaciens virulence, low transformation efficiencies, lack of stable integration of introduced genes, genotype dependence, and the production of chimeric plants among others [ 14 , 91 ].…”

“…Agrobacterium tumefaciens -mediated transformation remains the method of choice in plant gene editing experiments, but transformation of sunflower remains a challenge with efficiencies of 1–4% [ 14 , 90 , 91 ]. Sunflower is associated with a host of transformation limitations, including low A. tumefaciens virulence, low transformation efficiencies, lack of stable integration of introduced genes, genotype dependence, and the production of chimeric plants among others [ 14 , 91 ]. Several studies have focused on the improvement of sunflower transformation, including the establishment of genotype-wide A. tumefaciens transformation protocols through testing various factors affecting plant transformation, such as A. tumefaciens titre, co-culture period, and plant vitamin treatments [ 91 ].…”

“…True breeding lines can be obtained by repetitive backcrossing to the parental line containing the desirable trait and progeny selection or by developing haploids, with subsequent chromosome doubling to form doubled haploid (DH) lines [ 13 ]. Although sunflower doubled haploids have been previously applied in breeding programs [ 4 ], the absence in sufficiently diverse genetic resources and its recalcitrance to in vitro transformation have been a hindrance in the development of a doubled haploid induction procedure that could be efficiently used in breeding programs [ 14 , 15 ]. As an out-crossing crop, the lack of a double haploid system limits sunflower breeding and associated improvement processes, thereby delaying new trait developments.…”

LettuceGDB: The community database for lettuce genetics and omics

“…Lettuce has gradually become a model plant of the Asteraceae family and a suitable system for specific molecular biology studies owing to the availability of a high-quality reference genome and stable transformation systems ( Darqui et al., 2021 ). Abundant transcriptomic datasets and hundreds of re-sequenced varieties have been used to study transcriptional differences and genetic relationships among different cultivars and wild relatives ( Zhang et al., 2016 , 2017 ; Wei et al., 2021 ).…”