Gradual daylength sensing coupled with optimum cropping modes enhances multi-latitude adaptation of rice and maize

To expand crop planting areas,reestablishment of crop latitude adaptation based on genetic variation in photoperiodic genes can be performed,but it is quite time consuming.By contrast,a crop variety that already exhibits multi-latitude adaptation has the potential to increase its planting areas to be more widely and quickly available.However,the importance and potential of multi-latitude adaptation of crop varieties have not been systematically described.Here,combining daylength-sensing data with the cropping system of elite rice and maize varieties,we found that varieties with gradual daylength sensing coupled with optimum cropping modes have an enhanced capacity for multi-latitude adaptation in China.Furthermore,this multi-latitude adaptation expanded their planting areas and indirectly improved China’s nationwide rice and maize unit yield.Thus,coupling the daylength-sensing process with optimum cropping modes to enhance latitude adaptability of excellent varieties represents an exciting approach for deploying crop varieties with the potential to expand their planting areas and quickly improve nationwide crop unit yield in developing countries.

The DTH8-Hd1 Module Mediates Day-Length-Dependent Regulation of Rice Flowering

Photoperiodic flowering is one of the most important pathways to govern flowering in rice （Oryza sativa）, in which Heading date 1 （Hdl）, an ortholog of the Arabidopsis CONSTANS gene, encodes a pivotal regulator. Hdl promotes flowering under short-day conditions （SD） but represses flowering under long-day conditions （LD） by regulating the expression of Heading date 3a （Hd3a）, the FLOWERING LOCUS T （FT） ortholog in rice. However, the molecular mechanism of how Hdl changes its regulatory activity in response to day length remains largely unknown. In this study, we demonstrated that the repression of flowering in LD by Hdl is dependent on the transcription factor DAYS TO HEADING 8 （DTHS）. Loss of DTH8 function results in the activation of Hd3a by Hdl, leading to early flowering. We found that Hdl directly interacts with DTH8 and that the formation of the DTH8-Hd1 complex is necessary for the transcriptional repression of Hd3a by Hdl in LD, implicating that the switch of Hdl function is mediated by DTH8 in LD rather than in SD. Furthermore, we revealed that DTH8 associates with the Hd3a promoter to modulate the level of H3K27 trimethylation （H3K27me3） at the Hd3a locus. In the presence of the DTH8-Hdl complex, the H3K27me3 level was increased at Hd3a, whereas loss of DTH8 function resulted in decreased H3K27me3 level at Hd3a. Taken together, our findings indicate that, in response to day length, DTH8 plays a critical role in mediating the transcriptional regulation of Hd3a by Hdl through the DTH8-Hd1 module to shape epigenetic modifications in photoperiodic flowering.

Coordinated Transcriptional Regulation by the UVB Photoreceptor and Multiple Transcription Factors for Plant UV-B Responses

Non-damaging ultraviolet B(UV-B)light promotes photomorphogenic development and stress acclimation through UV-B-specific signal transduction in Arabidopsis.UV-B irradiation induces monomerization and nuclear translocation of the UV-B photoreceptor UV RESISTANCE LOCUS 8(UVR8).However,it is not clear how the nuclear localization of UVR8 leads to changes in global gene expression.Here,we reveal that nuclear UVR8 governs UV-B-responsive transcriptional networks in concert with several previously known transcription factors,including ELONGATED HYPOCOTYL 5(HY5)and PHYTOCHROME INTERACTING FACTOR 4(PIF4).Based on the transcriptomic analysis,we identify MYB13 as a novel positive regulator in UV-B-induced cotyledon expansion and stress acclimation.MYB13 is UV-B inducible and is predominantly expressed in the cotyledons.Our results demonstrate that MYB13 protein functions as a transcription factor to regulate the expression of genes involved in auxin response and flavonoid biosynthesis through direct binding with their promoters.In addition,photoactivated UVR8 interacts with MYB13 in a UV-B-dependent manner and differentially modulates the affinity of MYB13 with its targets.Taken together,our results elucidate the cooperative function of the UV-B photoreceptor UVR8 with various transcription factors in the nucleus to orchestrate the expression of specific sets of downstream genes and,ultimately,mediate plant responses to UV-B light.

Characterization and Fine Mapping of GLABROUS RICE 2 in Rice

Glabrous rice exhibits glabrous leaves and hulls because neither of these structures have trichomes on their surfaces. Glabrous rice varieties have become an important germplasm resource in the rice industry because they have considerable packaging efficiency and can reduce skin itching and dust during harvesting, drying, and packing （Shim et al., 2012; Zhang et al., 2012）.

OsELF3-2, an Ortholog of Arabidopsis ELF3, Interacts with the E3 Ligase APIP6 and Negatively Regulates Immunity against Magnaporthe oryzae in Rice

Dear Editor, The ubiquitin proteasome system （UPS） is a highly regulated mechanism of intracellular protein degradation in eukaryotes. The UPS comprises three key enzymes： ubiquitin-activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase enzyme E3. There are nearly 1500 E3 ligase genes in rice and Arabidopsis genomes that target substrates for many biological processes for plant growth and tolerance to abiotic and biotic stresses.

Optogenetic tools controlled by ultraviolet-B light

Decades of genetic,molecular and biochemical studies in plants have provided foundational knowledge about light sensory proteins and led to their application in synthetic biology.Optogenetic tools take advantage of the light switchable activity of plant photoreceptors to control intracellular signaling pathways.The recent discovery of the UV-B photoreceptor UV RESISTANCE LOCUS 8 in the model plant Arabidopsis thaliana opens up new avenues for light-controllable methodologies.In this review,we discuss current developments in optogenetic control by UV-B light and its signaling components,as well as rational considerations in the design and applications of UV-B-based optogenetic tools.