Summary: Thesfr6‐1mutant ofArabidopsis thalianawas identified previously on the basis of its failure to undergo acclimation to freezing temperatures following exposure to low positive temperatures. This failure is attributed to a defect in the pathway leading to cold on‐regulated (COR) gene expression via CBF (C‐box binding factor) transcription factors. We identified a region of chromosome 4 containingSFR6by positional mapping. Fine mapping of thesfr6‐1mutation proved impossible as the locus resides very close to the centromere. Therefore, we screened 380 T‐DNA lines with insertions in genes within the large region to whichsfr6‐1mapped. This resulted in the identification of two further mutant alleles ofSFR6(sfr6‐2andsfr6‐3); like the originalsfr6‐1mutation, these disrupt freezing tolerance andCORgene expression. To determine the protein sequence, we cloned anSFR6cDNA based on the predicted coding sequence, but this offered no indication as to the mechanism by which SFR6 acts. TheSFR6gene itself is not strongly regulated by cold, thus discounting regulation of SFR6 activity at the transcriptional level. We show that over‐expression of CBF1 or CBF2 transcription factors, which constitutively activateCORgenes in the wild‐type, cannot do so insfr6‐1. We demonstrate that CBF protein accumulates to wild‐type levels in response to cold insfr6‐1. These results indicate a role for the SFR6 protein in the CBF pathway ‐downstream of CBF translation. The fact that the SFR6 protein is targeted to the nucleus may suggest a direct role in modulating gene expression.

The sensitive to freezing2-1 (sfr2-1) mutation causes freezing sensitivity in Arabidopsis thaliana. By mapping, transgenic complementation, and sequencing, sfr2-1 was revealed to be a mutation in gene At3g06510. A new knockout allele was obtained, and its identical freezing-sensitive phenotype confirmed that the SFR2 gene product is essential for freezing tolerance. Transcription of SFR2 was observed to be constitutive rather than stress inducible and was distributed throughout most aerial tissues. SFR2 encodes a protein homologous to family 1 glycosyl hydrolases (β-glycosidases), but the predicted AtSFR2 protein is divergent from all other family 1 β-glycosidases of Arabidopsis, showing closer homology to the sequences of several β-glycosidases from thermophilic archea and bacteria. After purification from a heterologous expression system, AtSFR2 displayed a specific hydrolytic activity against β-d-glucosides.

New Zealand (NZ) is a small country with an export-led economy with above 90% of primary production exported. Plant-based primary commodities derived from the pastoral, horticultural and forestry sectors account for around half of the export earnings. Productivity is characterized by a history of innovation and the early adoption of advanced technologies. Gene editing has the potential to revolutionize breeding programmes, particularly in NZ. Here, perennials such as tree crops and forestry species are key components of the primary production value chain but are challenging for conventional breeding and only recently domesticated. Uncertainty over the global regulatory status of gene editing products is a barrier to invest in and apply editing techniques in plant breeding. NZs major trading partners including Europe, Asia and Australia are currently evaluating the regulatory status of these technologies and have not made definitive decisions. NZ is one of the few countries where the regulatory status of gene editing has been clarified. In 2014, the NZ Environmental Protection Authority ruled that plants produced via gene editing methods, where no foreign DNA remained in the edited plant, would not be regulated as GMOs. However, following a challenge in the High Court, this decision was overturned such that NZ currently controls all products of gene editing as GMOs. Here, we illustrate the potential benefits of integrating gene editing into plant breeding programmes using targets and traits with application in NZ. The regulatory process which led to gene editing's current GMO classification in NZ is described and the importance of globally harmonized regulations, particularly to small export-driven nations is discussed.