Search

Halophytes tolerate high salinity levels that would kill conventional crops. Understanding salt tolerance mechanisms will provide clues for breeding salt-tolerant plants. Many halophytes such as quinoa (Chenopodium quinoa) are covered by a layer of epidermal bladder cells (EBCs) that are thought to mediate salt tolerance by serving as salt dumps. We isolated an epidermal bladder cell-free quinoa mutant (ebcf) that completely lacked EBCs and was mutated in REBC and REBC-like1. This mutant showed no loss of salt stress tolerance. When wild-type quinoa plants were exposed to saline soil, EBCs accumulated K + as the major cation, in quantities far exceeding those for Na + . Emerging leaves densely packed with EBCs had the lowest Na + content, whereas old leaves with deflated EBCs served as Na + sinks. When the leaves expanded, K + was recycled from EBCs, resulting in turgor loss that led to a progressive deflation of EBCs. Our findings suggest that EBCs in young leaves serve as a K + -powered hydrodynamic system that functions as a water sink for solute storage. Na + accumulates within old leaves that subsequently wilt and are shed. This mechanism improves the survival of quinoa under high salinity.

Sustainable agriculture in the future will depend on crops that are tolerant to biotic and abiotic stresses, require minimal input of water and nutrients, and can be cultivated with a minimal carbon footprint. Wild plants that fulfil these requirements abound in nature but are typically low yielding. Thus, replacing current high-yielding crops with less productive but resilient species will require the intractable trade-off of increasing land area under cultivation to produce the same yield. Cultivating more land reduces natural resources, reduces biodiversity, and increases our carbon footprint. Sustainable intensification can be achieved by increasing yield in underutilized or wild plant species that are already resilient but achieving this goal by conventional breeding programs may be a long-term prospect. De novo domestication of orphan or crop wild relatives using mutagenesis is an alternative and fast approach to achieve resilient crops with high yield. With new precise molecular techniques it should be possible to reach economically sustainable yields in a much shorter period of time than ever before in the history of agriculture.

Chenopodium quinoa (quinoa) is a potential future major crop. However, one of its major setbacks is that some cultivars produce bitter saponins, which other cultivars do not and hence are called sweet. A previous study has indicated that a single nucleotide polymorphism in the last nucleotide of the third exon in the basic helix-loop-helix (bHLH) transcription factor TSARL1 can cause the sweet phenotype in quinoa cultivars. The purpose of this study was to investigate TSARL1 in five sweet cultivars and Titicaca, a known bitter cultivar that is able to grow in Denmark. To further investigate TSARL1 five bitter cultivars were chosen to be investigated on a genomic level. For this purpose, I examined TSARL1 at the genomic and transcript levels by sequencing the TSARL1. I amplified the TSARL1 gene including its 5’ upstream region from genomic DNA of the sweet cultivars and a total of six bitter cultivars, and subjected it to Sanger sequencing. Likewise, RNA was extracted to carry out reverse transcription (RT)-PCR in order to obtain the coding sequence of TSARL1 in the Titicaca cultivar and the sweet cultivars included in the study. Furthermore, all cultivars were phenotyped to ensure that they were different cultivars. I found that TSARL1 is in fact mutated at the previously reported position in the sweet cultivars of quinoa included in the study, and that the mutation leads to a truncated transcript of TSARL1, most likely because it affects a cryptic splice site within the third exon of TSARL1.