SlMYB72 affects pollen development by regulating autophagy in tomato

The formation and development of pollen are among the most critical processes for reproduction and genetic diversity in the life cycle of f lowering plants.The present study found that SlMYB72 was highly expressed in the pollen and tapetum of tomato f lowers.Downregulation of SlMYB72 led to a decrease in the amounts of seeds due to abnormal pollen development compared with wild-type plants.Downregulation of SlMYB72 delayed tapetum degradation and inhibited autophagy in tomato anther.Overexpression of SlMYB72 led to abnormal pollen development and delayed tapetum degradation.Expression levels of some autophagy-related genes(ATGs)were decreased in SlMYB72 downregulated plants and increased in overexpression plants.SlMYB72 was directly bound to ACCAAC/ACCAAA motif of the SlATG7 promoter and activated its expression.Downregulation of SlATG7 inhibited the autophagy process and tapetum degradation,resulting in abnormal pollen development in tomatoes.These results indicated SlMYB72 affects the tapetum degradation and pollen development by transcriptional activation of SlATG7 and autophagy in tomato anther.The study expands the understanding of the regulation of autophagy by SlMYB72,uncovers the critical role that autophagy plays in pollen development,and provides potential candidate genes for the production of male-sterility in plants.

Auxin response factor 6A regulates photosynthesis,sugar accumulation,and fruit development in tomato

Auxin response factors(ARFs)are involved in auxin-mediated transcriptional regulation in plants.In this study,we performed functional characterization of SlARF6A in tomato.SlARF6A is located in the nucleus and exhibits transcriptional activator activity.Overexpression of SlARF6A increased chlorophyll contents in the fruits and leaves of tomato plants,whereas downregulation of SlARF6A decreased chlorophyll contents compared with those of wild-type(WT)plants.Analysis of chloroplasts using transmission electron microscopy indicated increased sizes of chloroplasts in SlARF6A-overexpressing plants and decreased numbers of chloroplasts in SlARF6A-downregulated plants.Overexpression of SlARF6A increased the photosynthesis rate and accumulation of starch and soluble sugars,whereas knockdown of SlARF6A resulted in opposite phenotypes in tomato leaves and fruits.RNA-sequence analysis showed that regulation of SlARF6A expression altered the expression of genes involved in chlorophyll metabolism,photosynthesis and sugar metabolism.SlARF6A directly bound to the promoters of SlGLK1,CAB,and RbcS genes and positively regulated the expression of these genes.Overexpression of SlARF6A also inhibited fruit ripening and ethylene production,whereas downregulation of SlARF6A increased fruit ripening and ethylene production.SlARF6A directly bound to the SAMS1 promoter and negatively regulated SAMS1 expression.Taken together,these results expand our understanding of ARFs with regard to photosynthesis,sugar accumulation and fruit development and provide a potential target for genetic engineering to improve fruit nutrition in horticulture crops.

Photoregulated supramolecular hydrogels driven by polyradical interactions

Organic radical as a powerful tool has been extensively applied in synthetic chemistry. However, harnessing radical-mediated noncovalent interactions to fabricate soft materials remains elusive. Here we report a new category of supramolecular hydrogel system held by multiple radical-radical(polyradical) interactions, and its photosensitive cross-linking structure. A simple polyacrylamide with triarylamine(TAA)pendants is designed as the precursor. The TAA units in polymer can be converted into active TAA^(·+)radical cations with light and further associate each other via TAA^(·+)–TAA^(·+)stacking interactions to form stable supramolecular network. Temporal control of the light irradiation dictates the degree of radical stacks, thus regulating the mechanical performance of the resulting hydrogel materials on-demand. Moreover, the reversible collapse of this hydrogels can be promoted by adding radical scavenger or exerting reduction voltage.

Polymeric partners breathe together: using gas to direct polymer self-assembly via gas-bridging chemistry

The quest for a general and facile way to regulate polymer self-assembled nanostructures with low-to high-order ergodicity is an eternal theme in soft nanoparticle fabrication. Here we present an unprecedented gas-bridging strategy that allows to use gas to direct polymer self-assembly in continuous and tunable manners. Such system comprises a partner of frustrated Lewis polymers with bulky Lewis acid and base groups. They can together “breathe in” external gases to form gas-bridged structures between the two complementary moieties, which drive their mutual complexation and assemble into polymer nanoparticles of diverse geometries and dimensionalities. This strategy is applicable to a broad family of gas substances including but not limited to carbon oxides, nitrogen oxides, sulfur oxides, and even olefins;moreover, tailoring gas types and levels can dictate distinct assembling evolutionary pathways and deformable behaviors among spherical, fibrous, polymersomal, tubesomal and cubosomal morphologies. We also discover that the gas-based bonding chemistry is the mechanistic basis underlying the phase transitional control and phase window regulation. This will open a new direction of making bespoke polymer nanostructures with gas.