VAMP726 from maize and Arabidopsis confers pollen resistance to heat and UV radiation by influencing lignin content of sporopollenin.

Sporopollenin in the pollen cell wall protects male gametophytes from stresses. Phenylpropanoid derivatives, including guaiacyl (G) lignin units, are known to be structural components of sporopollenin, but the exact composition of sporopollenin remains to be fully resolved. We analyzed the phenylpropanoid derivatives in sporopollenin from maize and Arabidopsis by thioacidolysis coupled with nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS). The NMR and GC-MS results confirmed the presence of p-hydroxyphenyl (H), G, and syringyl (S) lignin units in sporopollenin from maize and Arabidopsis. Strikingly, H units account for the majority of lignin monomers in sporopollenin from these species. We next performed a genome-wide association study to explore the genetic basis of maize sporopollenin composition and identified a vesicle-associated membrane protein (ZmVAMP726) that is strongly associated with lignin monomer composition of maize sporopollenin. Genetic manipulation of VAMP726 affected not only lignin monomer composition in sporopollenin but also pollen resistance to heat and UV radiation in maize and Arabidopsis, indicating that VAMP726 is functionally conserved in monocot and dicot plants. Our work provides new insight into the lignin monomers that serve as structural components of sporopollenin and characterizes VAMP726, which affects sporopollenin composition and stress resistance in pollen.

Pronounced anti-neuroinflammatory jasmonates and terpenes isolated from lychee seeds.

Lychee is a favorite fruit of the Cantonese and native to Southeast Asia. In this study, the anti-neuroinflammatory bioactive compounds of lychee seeds have been carried out. Five new jasmonates (1, 2, 6-8) and seventeen known compounds were isolated using a series of chemical and chromatographic methods. Their chemical structures were identified through comprehensive spectroscopic analysis. Anti-neuroinflammatory activities were assayed and evaluated for the purified compounds. Most of the compounds exhibited pronounced anti-neuroinflammatory activities on nitric oxide (NO) induced by lipopolysaccharide (LPS) in BV-2 microglia cells. Moreover, compounds 1, 2 and 20 could reduce the expression of LPS-induced pro-inflammatory factors (iNOS and COX-2), inhibit the expression of mRNA levels of iNOS, COX-2, IL-6 and block NF-κB nuclear translocation in dose-dependent manners. This study suggested that lychee phytochemicals could be benefit to some neuroinflammatory-associated diseases, such as Alzheimer's disease.