Decreasing nitrogen assimilation under drought stress by suppressing DST-mediated activation of Nitrate Reductase 1.2 in rice

Nitrogen is an essential nutrient for plant growth and development,and plays vital roles in crop yield.Assimilation of nitrogen is thus fine-tuned in response to heterogeneous environments.However,the regulatory mechanism underlying this essential process remains largely unknown.Here,we report that a zinc-finger transcription factor,drought and salt tolerance(DST),controls nitrate assimilation in rice by regulating the expression of OsNR1.2.We found that loss of function of DSTresults in a significant decrease of nitrogen use efficiency(NUE)in the presence of nitrate.Furtherstudy revealed that DST is required for full nitrate reductase activity in rice and directly regulates the expression of OsNR1.2,a gene showing sequence similarity to nitrate reductase.Reverse genetics and biochemistry studies revealed that OsNR1.2 encodes an NADH-dependent nitrate reductase that is required for high NUE of rice.Interestingly,the DST-OsNR1.2 regulatory module is involved in the suppression of nitrate assimilation under drought stress,which contributes to drought tolerance.Considering the negative role of DST in stomata closure,as revealed previously,the positive role of DST in nitrogen assimilation suggests a mechanism couplingni-trogen metabolism and stomata movement.The discovery of this coupling mechanism will aid the engi-neering of drought-tolerant crops with high NUE in the future.

Long-distance blue light signalling regulates phosphate deficiency-induced primary root growth inhibition

Although roots are mainly embedded in the soil, recent studies revealed that light regulates mineral nutrient uptake by roots. However, it remains unclear whether the change in root system architecture in response to different rhizosphere nutrient statuses involves light signaling. Here, we report that blue light regulates primary root growth inhibition under phosphate-deficient conditions through the cryptochromes and their downstream signaling factors. We showed that the inhibition of root elongation by low phosphate requires blue light signal perception at the shoot and transduction to the root. In this process, SPA1 and COP1 play a negative role while HY5 plays a positive role. Further experiments revealed that HY5 is able to migrate from the shoot to root and that the shoot-derived HY5 autoactivates root HY5 and regulates primary root growth by directly activating the expression of LPR1, a suppressor of root growth under phosphate starvation. Taken together, our study reveals a regulatory mechanism by which blue light signaling regulates phosphate deficiency-induced primary root growth inhibition, providing new insights into the crosstalk between light and nutrient signaling.

Long-distance blue light signalling regulates phosphate deficiency-induced primary root growth inhibition

(Molecular Plant 14,1539–1553;September 62021)In Figure 4G,we showed the root apical meristem lengths of different genotypes.However,because of inappropriate use of the software Adobe Illustrator(AI)and the high degree of similarity between the pictures,we mistakenly kept the picture of Col-0(panel of 50μM Pi),which was set as an object of reference in a lower layer for all the other panels for typesetting purposes and should have been deleted after typesetting,in the position of cry1cry2 mutant.A similar mistake also happened in Figure S15,in which we kept the GUS staining picture of line#3(panel of pLPR1::GUS/hy5)in the position of line#8.The wrong pictures in these two figures have been substituted with correct pictures in the figure below.The authors sincerely apologize for the mistakes.