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SummarySpike development of wheat line 3558M was strongly inhibited by low temperature stress in spring. The fertile tiller inhibition (ftin) gene in the wheat line 3558M is associated with multiple phenotypes, including the production of fewer tillers, delayed floral transition, and death of the shoot apical meristem. We systematically investigated the genes and pathways underlying the differences using ITRAQ proteomics and RNA-sequencing technologies and found multiple biological pathways including to the cold acclimation pathway and multiple defence responses (e.g. reactive oxygen species-mediated hypersensitive response, salicylic acid-mediated systemic acquired resistance) are activated and led to tillers death of the wheat line 3558M under cold stress. Meanwhile, the cold acclimation pathway inhibited the SVP-SCO1-LFY flowering pathway and led to delayed floral transition. Particularly, two TaPIN proteins were significantly downregulated, and multiple auxin signalling genes were also differentially expressed. Knocking down the two TaPIN genes using RNAi technology significantly reduced the tiller number. The cold stress inhibited the auxin transport to reduce the tillers of 3558M. Taken together, the ftin gene might be a cold-sensitive mutation and that is the cause of multiple biological pathways and phenotypic changes.

Spike development of wheat line 3558M was strongly inhibited by low temperature stress in spring. The fertile tiller inhibition (ftin) gene in the wheat line 3558M is associated with multiple phenotypes, including the production of fewer tillers, delayed floral transition, and death of the shoot apical meristem. In order to study the relationship between spike development inhibition and response to cold stress, we systematically investigated the genes and pathways underlying the differences using ITRAQ proteomics and RNA-sequencing technologies. The results showed that the cold acclimation pathway and multiple defence responses, including reactive oxygen species-mediated hypersensitive response, salicylic acid-mediated systemic acquired resistance, are activated and led to apex death of the wheat line 3558M under cold stress. Meanwhile, the cold acclimation pathway inhibited the SVP-SCO1-LFY flowering pathway and led to delayed floral transition. Two TaPIN proteins were significantly downregulated, and multiple auxin signalling genes were also differentially expressed. Particularly, knocking down the two TaPIN genes using RNAi technology significantly reduced the tiller number. The cold stress might disrupt the distribution of auxin and reduce the tillers of 3558M. Taken together, the ftin gene might be a cold-sensitive mutation and that is the cause of multiple biological pathways and phenotypic changes.

As an important oilseed worldwide, Camelina sativa is being increasingly explored for its use in production of food, feed, biofuel and industrial chemicals. However, detailed mechanisms of camelina oil biosynthesis and accumulation, particularly in vegetative tissues, are understood to a very small extent. Here, we present genome-wide identification, cloning and functional analysis of phospholipid diacylglycerol acyltransferase (PDAT) in C. sativa, which catalyses the final acylation step in triacylglycerol (TAG) biosynthesis by transferring a fatty acyl moiety from a phospholipid to diacylglycerol (DAG). We identified five genes (namely CsPDAT1-A, B, and C and CsPDAT2-A and B) encoding PDATs from the camelina genome. CsPDAT1-A is mainly expressed in seeds, whereas CsPDAT1-C preferentially accumulates in flower and leaf tissues. High expression of CsPDAT2-A and CsPDAT2-B was detected in stem and root tissues, respectively. Cold stress induced upregulation of CsPDAT1-A and CsPDAT1-C expression by 3.5- and 2.5-fold, respectively, compared to the control. Salt stress led to an increase in CsPDAT2-B transcripts by 5.1-fold. Drought treatment resulted in an enhancement of CsPDAT2-A mRNAs by twofold and a reduction of CsPDAT2-B expression. Osmotic stress upregulated the expression of CsPDAT1-C by 3.3-fold. Furthermore, the cDNA clones of these CsPDAT genes were isolated for transient expression in tobacco leaves. All five genes showed PDAT enzymatic activity and substantially increased TAG accumulation in the leaves, with CsPDAT1-A showing a higher preference for ɑ-linolenic acid (18:3 ω-3). Overall, this study demonstrated that different members of CsPDAT family contribute to TAG synthesis in different tissues. More importantly, they are involved in different types of stress responses in camelina seedlings, providing new evidence of their roles in oil biosynthesis and regulation in camelina vegetative tissue. The identified CsPDATs may have practical applications in increasing oil accumulation and enhancing stress tolerance in other plants as well., Summary: Five CsPDAT family members were identified from Camelina sativa and they contribute to TAG synthesis in different tissues and various stress responses, offering new targets for lipid metabolic engineering.

The plant-specific WRINKLED1 (WRI1) is a member of the AP2/EREBP class of transcription factors that positively regulate oil biosynthesis in plant tissues. Limited information is available for the role of WRI1 in oil biosynthesis in castor bean (Ricinus connunis L.), an important industrial oil crop. Here, we report the identification of two alternatively spliced transcripts of RcWRI1, designated as RcWRI1-A and RcWRI1-B. The open reading frames of RcWRI1-A (1341 bp) and RcWRI1-B (1332 bp) differ by a stretch of 9 bp, such that the predicted RcWRI1-B lacks the three amino acid residues “VYL” that are present in RcWRI1-A. The RcWRI1-A transcript is present in flowers, leaves, pericarps and developing seeds, while the RcWRI1-B mRNA is only detectable in developing seeds. When the two isoforms were individually introduced into an Arabidopsis wri1-1 loss-of-function mutant, total fatty acid content was almost restored to the wild-type level, and the percentage of the wrinkled seeds was largely reduced in the transgenic lines relative to the wri1-1 mutant line. Transient expression of each RcWRI1 splice isoform in N. benthamiana leaves upregulated the expression of the WRI1 target genes, and consequently increased the oil content by 4.3–4.9 fold when compared with the controls, and RcWRI1-B appeared to be more active than RcWRI1-A. Both RcWRI1-A and RcWRI1-B can be used as a key transcriptional regulator to enhance fatty acid and oil biosynthesis in leafy biomass.