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To clarify the quality characters, understand the genetic diversity and screen elite lines among different oilseed sunflowers, the contents of crude fat, oleic acid, linoleic acid, palmitic acid and stearic acid of 525 oil sunflowers (including 375 germplasm accessions and 150 inbred lines) were detected by near-infrared spectroscopy (NIRS); the genetic variation and correlation analysis of quality traits were also performed. The results showed that oleic acid and linoleic acid had rich diversities with large variation ranges for each material type. Similar to the relation between crude fat content and palmitic acid content, significantly negative relation with high estimated value existed between oleic acid and linoleic acid content, while stearic acid content positively associated with oleic acid and palmitic acid content. Principal component analysis indicated that 5 quality traits were integrated into 2 principal component factors (linoleic acid negative factor and palmitic acid factor) with the contribution rate of 88.191%, which could be used for evaluating sunflower quality. 525 oilseed sunflowers were clustered into 3 groups with obvious differences of quality characters, materials in Group I had high contents of oleic acid and low crude fat, but the opposite was found in Group III. 59 superior quality accessions were obtained using large-scale and rapid near-infrared spectroscopy, and these excellent materials were verified by the traditional national chemical standard method. This research provided materials and significant reference for sunflower genetic research and quality breeding.

Abstract Background Oil flax (linseed, Linum usitatissimum L.) is one of the most important oil crops., However, the increases in drought resulting from climate change have dramatically reduces linseed yield and quality, but very little is known about how linseed coordinates the expression of drought resistance gene in response to different level of drought stress (DS) on the genome-wide level. Results To explore the linseed transcriptional response of DS and repeated drought (RD) stress, we determined the drought tolerance of different linseed varieties. Then we performed full-length transcriptome sequencing of drought-resistant variety (Z141) and drought-sensitive variety (NY-17) under DS and RD stress at the seedling stage using single-molecule real-time sequencing and RNA-sequencing. Gene Ontology (GO) and reduce and visualize GO (REVIGO) enrichment analysis showed that upregulated genes of Z141 were enriched in more functional pathways related to plant drought tolerance than those of NY-17 were under DS. In addition, 4436 linseed transcription factors were identified, and 1190 were responsive to stress treatments. Moreover, protein-protein interaction (PPI) network analysis showed that the proline biosynthesis pathway interacts with stress response genes through RAD50 (DNA repair protein 50) interacting protein 1 (RIN-1). Finally, proline biosynthesis and DNA repair structural gene expression patterns were verified by RT- PCR. Conclusions The drought tolerance of Z141 may be related to its upregulation of drought tolerance genes under DS. Proline may play an important role in linseed drought tolerance by maintaining cell osmotic and protecting DNA from ROS damage. In summary, this study provides a new perspective to understand the drought adaptability of linseed.