Cloning and characterization of the MYB transcription factor gene GhTT2 in Gossypium hirsutum.

As one of the important secondary metabolites, proanthocyanidins (PAs) are not only a defense mechanism for plants to cope with biotic and abiotic stresses, but also a key factor affecting the development and quality of plants. Although the biosynthetic and metabolic pathways of proanthocyanidins have been basically clarified in the model plants, the regulatory mechanism in cotton has not been fully elucidated. In this work, a transcription factor gene GhTT2 (transparent testa 2) was cloned from Gossypium hirsutum. Its gene structure, expression pattern, subcellular localization, and function were further analyzed. The results show that the GhTT2 has a typical MYB domain and is predominantly expressed in fibers. Its transcription level was negatively correlated with anthocyanin content. The GhTT2-GFP fusion protein is located in the nucleus. Moreover, yeast transformation results show that GhTT2 has obvious transcriptional activation characteristics. Furthermore, the content of proanthocyanidins in GhTT2-silenced cottons is significantly reduced, indicating that GhTT2 may be involved in regulation of the proanthocyanidins biosynthesis in Gossypium hirsutum. These results provide a reference for further elucidating the molecular mechanisms of MYB transcription factors involved in the regulation of the biosynthetic pathway of PAs.

With DNA barcoding revealing sexual dimorphism in a water mite: the first description of male Sperchon fuxiensis (Acari: Hydrachnidia: Sperchontidae).

Sperchon fuxiensis Zhang, 2017 was published as a new species based on females alone. Two males of Sperchon were found in the same locality during our recent collection. The males resemble S. fuxiensis female in the integument pattern, excretory pore and the palps shape, but the chitinous plates of both dorsum and venter differ greatly. The males were paired with the female of S. fuxiensis using DNA barcoding, revealing unusual sexual dimorphism in the species. Descriptions and illustrations of the male of S. fuxiensis are given in the present study. Species identification based on the full-length DNA barcoding (658bp) of COI in water mites is also discussed.