The nitrate-responsive transcription factor Md NLP7 regulates callus formation by modulating auxin response

Under appropriate culture conditions,plant cells can regenerate new organs or even whole plants.De novo organ regeneration is an excellent biological system,which usually requires additional growth regulators,including auxin and cytokinin.Nitrate is an essential nutrient element for plant vegetative and reproductive development.It has been reported that nitrate is involved in auxin biosynthesis and transport throughout the growth and development of plants.In this study,we demonstrated that the ectopic expression of the MdNLP7 transcription factor in Arabidopsis could regulate the regeneration of root explants.MdNLP7 mainly participated in the regulation of callus formation,starting with pericycle cell division,and mainly affected auxin distribution and accumulation in the regulation process.Moreover,MdNLP7 upregulated the expression of genes related to auxin biosynthesis and transport in the callus formation stage.The results demonstrated that MdNLP7 may play a role in the nitrate-modulated regeneration of root explants.Moreover,the results revealed that nitrate–auxin crosstalk is required for de novo callus initiation and clarified the mechanisms of organogenesis.

The effect of 2, 4-Dichlorophenoxy acetic acid and Bradyrhizobium on induction of Para-nodule in wheat roots

The investigation was conducted to know the effect of 2, 4-Dichlorophenoxy acetic acid and inoculation on Para-nodule formation and growth parameters in wheat. Formation of nodular outgrowth on the roots of wheat seedlings treated with 2, 4-D commenced in 8-10 days. The maximum Para-nodule formation was found in 1 ppm of 2, 4-D when incubated with bradyrhizobium P-132. Inoculation of the same has helped to increase the number of Para-nodule, but not essential for Para-nodulation. Histological study shows that, these induced Para-nodules originated from the pericycle and these are appeared to be modified lateral roots and Para-nodule structure formations however, it enhanced by bradyrhizobial inoculation.

Knockout of a rice K5.2 gene increases Ca accumulation in the grain

Rice is a staple food for half of the world’s population,but it is a poor dietary source of calcium(Ca)due to the low concentration.It is an important issue to boost Ca concentration in this grain to improve Ca deficiency risk,but the mechanisms underlying Ca accumulation are poorly understood.Here,we obtained a rice(Oryza sativa)mutant with high shoot Ca accumulation.The mutant exhibited 26%-53% higher Ca in shoots than did wild-type rice(WT)at different Ca supplies.Ca concentration in the xylem sap was 36% higher in the mutant than in the WT.There was no difference in agronomic traits between the WT and mutant,but the mutant showed 25% higher Ca in the polished grain compared with the WT.Map-based cloning combined with a complementation test revealed that the mutant phenotype was caused by an 18-bp deletion of a gene,OsK5.2,belonging to the Shaker-like K+channel family.OsK5.2 was highly expressed in the mature region of the roots and its expression in the roots was not affected by Ca levels,but upregulated by low K.Immunostaining showed that OsK5.2 was mainly expressed in the pericycle of the roots.Taken together,our results revealed a novel role for OsK5.2 in Ca translocation in rice,and will be a good target for Ca biofortification in rice.

Total Synthesis of Laurane and Guaiane Sesquiterpenoids via Oxidative Nazarov Reaction

As one of the most common structural motifs in natural products,cyclopentenones usually can be fabricated by Nazarov cyclization using divinyl ketones or functionalized tertiary divinyl carbinols(TDCs)as substrates.However,straightforward method for transforming unfunctionalized TDCs to their corresponding cyclopentenones is currently lacking.Herein,we wish to report the total syntheses of four structurally distinct terpenoids,namely laurane-type marine sesquiterpenoids isolaurene,debromoaplysin and aplysin,and guaiane sesquiterpenoid guaiadienone A,all using a novel synthetic method,named oxidative Nazarov cyclization,as the key step.This work demonstrated our robust method is suitable for synthesizing various highly substituted cyclopentenones.

Overview of 6π 1,5-Electrocyclization over the Past 40 Years

As an important part of pericyclic reaction,6π 1,5-electrocyclization plays an important role in organic synthesis and chemical theory.Many types of five-membered rings could be constructed via 1,5-electrocyclization with high atom economy.Some elegant works have been reported in this field in the past few decades.However,it still needs a lot of effort in further advancements of 1,5-electrocyclization.