Editorial: physiological, molecular and genetic perspectives of chilling tolerance in horticultural crops

Horticultural crops have high economic, and enrich our lives through their aesthetic and nutritional value. Many horticultural species originate from tropical regions and are sensitive to cold at every stage of their lifecycle. Cold stress leads to lower productivity and post-harvest losses in these species, with poor economic and environmental outcomes. Better understanding of the protective mechanisms mediated by hormonal and other signaling pathways (Akhtar et al., 2012) may offer solutions to reduce cold-stress induced losses. The papers included in this collection illustrate this concept, examining natural cold-tolerance mechanisms and practical ways for growers to alleviate chilling stress and to reduce crop losses. The studies were remarkably diverse in terms of the species studied (i.e., tomato, longan, tung tree, lowbush blueberry, and apple), plant organs examined (i.e., seedlings, leaf, and fruit), and approaches used (i.e., reverse genetics, the systems biology, physiology, and biochemistry). The papers encompassed the use of (1) basic science, aimed at identifying key genes and their roles in cold signal transduction and protective pathways in fruit and photosynthetic tissues; (2) reverse genetics for proof-of-concept on the hypothesized role of a cold-tolerance transcription factor cloned from an understudied species; and (3) emerging technologies, by using exogenous hormones and signaling compounds to mitigate the harmful effects of chilling. These studies are described belowFil: Lara, Isabel. Universidad de Lleida; EspañaFil: Drincovich, Maria Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Beckles, Diane M.. University of California at Davis; Estados UnidosFil: Cao, Shifeng. Zhejiang Wanli University; Chin

Editorial: Physiological, Molecular and Genetic Perspectives of Chilling Tolerance in Horticultural Crops

Horticultural crops have high economic, and enrich our lives through their aesthetic and nutritional value. Many horticultural species originate from tropical regions and are sensitive to cold at every stage of their lifecycle. Cold stress leads to lower productivity and post-harvest losses in these species, with poor economic and environmental outcomes. Better understanding of the protective mechanisms mediated by hormonal and other signaling pathways (Akhtar et al., 2012) may offer solutions to reduce cold-stress induced losses. The papers included in this collection illustrate this concept, examining natural cold-tolerance mechanisms and practical ways for growers to alleviate chilling stress and to reduce crop losses. The studies were remarkably diverse in terms of the species studied (i.e., tomato, longan, tung tree, lowbush blueberry, and apple), plant organs examined (i.e., seedlings, leaf, and fruit), and approaches used (i.e., reverse genetics, the systems biology, physiology, and biochemistry). The papers encompassed the use of (1) basic science, aimed at identifying key genes and their roles in cold signal transduction and protective pathways in fruit and photosynthetic tissues; (2) reverse genetics for proof-of-concept on the hypothesized role of a cold-tolerance transcription factor cloned from an understudied species; and (3) emerging technologies, by using exogenous hormones and signaling compounds to mitigate the harmful effects of chilling. These studies are described below.Current work at IL's lab was funded by grant AGL2015-64235-R from the Plan Nacional de I+D, Ministry of Education and Science, Spain. DB acknowledges funding from the US-Israeli Binational Agricultural Research Development Grant no. #IS-5196-19. Fund and the AES Hatch Project CA-D-PLS-2404-H. Work at MD's lab was funded by National Research Council and National Agency for the Promotion of Scientific and Technological Activities from Argentina

Editorial: physiological, molecular and genetic perspectives of chilling tolerance in horticultural crops, volume II

For crops of tropical and subtropical origin, exposure to low temperatures often causes chilling injury symptoms, which can range from altered appearance (such as surface pitting and discoloration) to severe physiological disorders and impaired metabolism. To cope with suboptimal temperatures in the surrounding environment, crops have evolved complex mechanisms, which entail stress signal perception and transduction, activation of stress-responsive genes, and the synthesis of stressrelated molecules. Plant breeding programs have been instrumental in obtaining chilling-tolerant cultivars in a number of horticultural crops. More recently, the incorporation of molecular and omics-based techniques into conventional breeding procedures has vastly improved breeding strategies by enhancing the efficacy of screening for chilling tolerance-associated traits. Moreover, these new tools will boost knowledge of chilling responses and tolerance mechanisms, and the discovery of related pathways and genes. As a part of the 'Physiological, Molecular and Genetic Perspectives of Chilling Tolerance in Horticultural Crops' series (Lara et al., 2020), this Research Topic was launched with the aim of offering an overview of recent developments in this area. The papers in this collection explored the mechanisms involved in chilling tolerance in a number of plant species, including commercially important fruit crops such as pepper, tomato, banana and peach/nectarine, a medicinal plant (Tetrastigma hemsleyanum) and Arabidopsis. In addition to helping to reveal the mechanisms underlying cold stress tolerance, these findings provide the basis for future breeding programs, and offer clues for the alleviation of stress symptoms.Current work at IL’s lab is funded by grant 2017 SGR 1108 (Generalitat de Catalunya, Catalonia, Spain). DB acknowledges funding from the US-Israeli Binational Agricultural Research Development Fund and the AES Hatch Project CA-D-PLS-2404-H. Work at MD’s lab is funded by National Research Council and National Agency for the Promotion of Scientific and Technological Activities from Argentina

MrMYB6 From Chinese Bayberry (Myrica rubra) Negatively Regulates Anthocyanin and Proanthocyanidin Accumulation

Anthocyanins and proanthocyanidins (PAs) are important flavonoids in Chinese bayberry (Morella rubra), which functions in fruit color and exhibits multiple health promoting and disease-preventing effects. To investigate the regulation of their biosynthesis in Chinese bayberries, we isolated and identified a subgroup 4 MYB transcription factor (TF), MrMYB6, and found MrMYB6 shared similar repressor domains with other MYB co-repressors of anthocyanin and PA biosynthesis after sequence analysis. Gene expression results revealed the transcripts of MrMYB6 were negatively correlated with the anthocyanin and insoluble PA contents and also with the gene expressions involved in anthocyanin biosynthesis and PA specific genes such as MrLAR and MrANR during the late ripening stages of bayberries. In addition, overexpression of MrMYB6 in tobacco inhibited the transcript levels of NtCHI, NtLAR, and NtANR2, resulting into a decline in the levels of anthocyanins and PAs in tobacco flowers. We further found that MrMYB6 interacted with MrbHLH1 and MrWD40-1 to form functional complexes that acted to directly repress the promoter activities of the PA-specific gene MrLAR and MrANR and the anthocyanin-specific gene MrANS and MrUFGT. Taken together, our results suggested that MrMYB6 might negatively regulate anthocyanin and PA accumulation in Chinese bayberry

SAG101 Forms a Ternary Complex with EDS1 and PAD4 and Is Required for Resistance Signaling against Turnip Crinkle Virus

EDS1, PAD4, and SAG101 are common regulators of plant immunity against many pathogens. EDS1 interacts with both PAD4 and SAG101 but direct interaction between PAD4 and SAG101 has not been detected, leading to the suggestion that the EDS1-PAD4 and EDS1-SAG101 complexes are distinct. We show that EDS1, PAD4, and SAG101 are present in a single complex in planta. While this complex is preferentially nuclear localized, it can be redirected to the cytoplasm in the presence of an extranuclear form of EDS1. PAD4 and SAG101 can in turn, regulate the subcellular localization of EDS1. We also show that the Arabidopsis genome encodes two functionally redundant isoforms of EDS1, either of which can form ternary complexes with PAD4 and SAG101. Simultaneous mutations in both EDS1 isoforms are essential to abrogate resistance (R) protein-mediated defense against turnip crinkle virus (TCV) as well as avrRps4 expressing Pseudomonas syringae. Interestingly, unlike its function as a PAD4 substitute in bacterial resistance, SAG101 is required for R-mediated resistance to TCV, thus implicating a role for the ternary complex in this defense response. However, only EDS1 is required for HRT-mediated HR to TCV, while only PAD4 is required for SA-dependent induction of HRT. Together, these results suggest that EDS1, PAD4 and SAG101 also perform independent functions in HRT-mediated resistance

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure