Effects of Extraction Technique on the Content and Antioxidant Activity of Flavonoids from Gossypium Hirsutum linn. Flowers.

Cotton is one of the Uyghur medical materials in China and is rich in flavonoids. Flavonoids have important pharmacological effects. The yield of flavonoids in traditional extraction methods is low, which affects the development of flavonoids. Therefore, it is urgent to optimize the extraction techniques. The yield of flavonoids in cotton flowers was effectively improved by response surface methodology, and the highest yield of flavonoids reached 5.66%, and the optimal extraction process conditions were obtained. The DPPH free radical scavenging rate, hydroxyl free radical scavenging rate, superoxide anion free radical scavenging rate, and reducing ability were tested to reflect the antioxidant capacity of flavonoids. The flavonoids had an excellent antioxidant effect. Cell experiments suggested that the flavonoids had the effect of protecting glutamate-induced damage to HT-22 cells. The results of this study provide a theoretical basis for the extraction of cotton flowers flavonoids and the comprehensive evaluation of antioxidant products, as well as the extraction of other plant flavonoids.

A novel GhBEE1-Like gene of cotton causes anther indehiscence in transgenic Arabidopsis under uncontrolled transcription level.

Male-sterile lines are very important for selective breeding, and anther dehiscence defect is an effective way to generate male-sterile lines. Although several bHLH-family proteins in Arabidopsis have been characterized, little is known about the role of bHLH-family proteins in cotton. Here, we isolated a novel bHLH protein from cotton (Gossypium hirsutum), named GhBEE1-Like. Protein domain analysis showed that GhBEE1-Like contained a basic domain and an HLH domain. Subcellular localization analysis revealed that GhBEE1-Like was a nuclear-localized protein. Expression pattern analysis showed GhBEE1-Like was highly expressed in floral organs, and its expression was induced by the active brassinosteroid (BR) substance 24-epi-BL. GhBEE1-Like overexpression in Arabidopsis resulted in two types of transgenic lines, one with normal anther dehiscence and the other with defective anther dehiscence. Semi-qRT-PCR and qRT-PCR analyses revealed that GhBEE1-Like transcript levels acted as a check-point determining how anther dehiscence proceeds in these transgenic lines; regulated transcript levels result in normal anther dehiscence, whereas uncontrolled transcript levels lead to anther indehiscence. These results suggest that GhBEE1-Like plays an important role via its accumulation in regulating anther dehiscence. Therefore, controlling the level of GhBEE1-Like expression in cotton could be a convenient tool for generating male-sterile lines to use in selective breeding.

The mitochondrial malate dehydrogenase 1 gene GhmMDH1 is involved in plant and root growth under phosphorus deficiency conditions in cotton.

Cotton, an important commercial crop, is cultivated for its natural fibers, and requires an adequate supply of soil nutrients, including phosphorus, for its growth. Soil phosporus exists primarily in insoluble forms. We isolated a mitochondrial malate dehydrogenase (MDH) gene, designated as GhmMDH1, from Gossypium hirsutum L. to assess its effect in enhancing P availability and absorption. An enzyme kinetic assay showed that the recombinant GhmMDH1 possesses the capacity to catalyze the interconversion of oxaloacetate and malate. The malate contents in the roots, leaves and root exudates was significantly higher in GhmMDH1-overexpressing plants and lower in knockdown plants compared with the wild-type control. Knockdown of GhmMDH1 gene resulted in increased respiration rate and reduced biomass whilst overexpression of GhmMDH1 gave rise to decreased respiration rate and higher biomass in the transgenic plants. When cultured in medium containing only insoluble phosphorus, Al-phosphorus, Fe-phosphorus, or Ca-phosphorus, GhmMDH1-overexpressing plants produced significantly longer roots and had a higher biomass and P content than WT plants, however, knockdown plants showed the opposite results for these traits. Collectively, our results show that GhmMDH1 is involved in plant and root growth under phosphorus deficiency conditions in cotton, owing to its functions in leaf respiration and P acquisition.