The Plant Journal

doi: 10.1111/tpj.15824pmid: N/A

Pierroz, Grady

doi: 10.1111/tpj.16325pmid: 37323060

Chen, Jian; Luo, Ming; Hands, Phillip; Rolland, Vivien; Zhang, Jianping; Li, Zhao; Outram, Megan; Dodds, Peter; Ayliffe, Michael

doi: 10.1111/tpj.16234pmid: 37323061

Protein–protein interactions (PPIs) are a fundamental process in cellular biogenesis. Here we have developed a split GAL4 RUBY assay that enables macroscopically visual PPI detection in plant leaves in real time. Candidate interacting protein partners are fused to specific domains of the yeast GAL4 and herpes simplex virus VP16 transcription factors and transiently expressed in Nicotiana benthamina leaves by Agrobacterium infiltration. PPI, that may be either direct or indirect, results in transcriptional activation of a RUBY reporter gene leading to the production of the highly visual metabolite, betalain, in leaf tissue of living plants. Samples require no processing for in planta visual qualitative assessment, but with very simple processing steps the assay is quantitative. Its accuracy is demonstrated using a series of known interacting protein partners and mutant derivatives including transcription factors, signalling molecules and plant resistance proteins with cognate pathogen effectors. Using this assay, association between the wheat Sr27 stem rust disease resistance protein and corresponding AvrSr27 avirulence effector family produced by the rust pathogen is detected. Interaction is also observed between this resistance protein and the effector encoded by the corresponding avrSr27‐3 virulence allele. However, this association appears weaker in the split GAL4 RUBY assay, which coupled with lower avrSr27‐3 expression during stem rust infection, likely enables virulent races of the rust pathogen to avoid Sr27‐mediated detection.

Sardans, Jordi; Lambers, Hans; Preece, Catherine; Alrefaei, Abdulwahed Fahad; Penuelas, Josep

doi: 10.1111/tpj.16184pmid: 36917083

Anthropogenic global change is driving an increase in the frequency and intensity of drought and flood events, along with associated imbalances and limitation of several soil nutrients. In the context of an increasing human population, these impacts represent a global‐scale challenge for biodiversity conservation and sustainable crop production to ensure food security. Plants have evolved strategies to enhance uptake of soil nutrients under environmental stress conditions; for example, symbioses with fungi (mycorrhization) in the rhizosphere and the release of exudates from roots. Although crop cultivation is managed for the effects of limited availability of nitrogen (N) and phosphorus (P), there is increasing evidence for limitation of plant growth and fitness because of the low availability of other soil nutrients such as the metals potassium (K), calcium (Ca), magnesium (Mg), and iron (Fe), which may become increasingly limiting for plant productivity under global change. The roles of mycorrhizas and plant exudates on N and P uptake have been studied intensively; however, our understanding of the effects on metal nutrients is less clear and still inconsistent. Here, we review the literature on the role of mycorrhizas and root exudates in plant uptake of key nutrients (N, P, K, Ca, Mg, and Fe) in the context of potential nutrient deficiencies in crop and non‐crop terrestrial ecosystems, and identify knowledge gaps for future research to improve nutrient‐uptake capacity in food crop plants.

Bellec, Arnaud; Sow, Mamadou Dia; Pont, Caroline; Civan, Peter; Mardoc, Emile; Duchemin, Wandrille; Armisen, David; Huneau, Cécile; Thévenin, Johanne; Vernoud, Vanessa; Depège‐Fargeix, Nathalie; Maunas, Laurent; Escale, Brigitte; Dubreucq, Bertrand; Rogowsky, Peter;

Mankotia, Samriti; Singh, Dhriti; Monika, Kumari; Kalra, Muskan; Meena, Himani; Meena, Varsha; Yadav, Ram Kishor; Pandey, Ajay Kumar; Satbhai, Santosh B.

doi: 10.1111/tpj.16191pmid: 36920240

Iron (Fe) is an essential micronutrient for both plants and animals. Fe‐limitation significantly reduces crop yield and adversely impacts on human nutrition. Owing to limited bioavailability of Fe in soil, plants have adapted different strategies that not only regulate Fe‐uptake and homeostasis but also bring modifications in root system architecture to enhance survival. Understanding the molecular mechanism underlying the root growth responses will have critical implications for plant breeding. Fe‐uptake is regulated by a cascade of basic helix–loop–helix (bHLH) transcription factors (TFs) in plants. In this study, we report that HY5 (Elongated Hypocotyl 5), a member of the basic leucine zipper (bZIP) family of TFs, plays an important role in the Fe‐deficiency signaling pathway in Arabidopsis thaliana. The hy5 mutant failed to mount optimum Fe‐deficiency responses, and displayed root growth defects under Fe‐limitation. Our analysis revealed that the induction of the genes involved in Fe‐uptake pathway (FIT‐FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR, FRO2‐FERRIC REDUCTION OXIDASE 2 and IRT1‐IRON‐REGULATED TRANSPORTER1) is reduced in the hy5 mutant as compared with the wild‐type plants under Fe‐deficiency. Moreover, we also found that the expression of coumarin biosynthesis genes is affected in the hy5 mutant under Fe‐deficiency. Our results also showed that HY5 negatively regulates BRUTUS (BTS) and POPEYE (PYE). Chromatin immunoprecipitation followed by quantitative polymerase chain reaction revealed direct binding of HY5 to the promoters of BTS, FRO2 and PYE. Altogether, our results showed that HY5 plays an important role in the regulation of Fe‐deficiency responses in Arabidopsis.

Dong, Rongrong; Yuan, Yaqin; Liu, Zhiqiang; Sun, Shuai; Wang, Haijing; Ren, Huazhong; Cui, Xia; Li, Ren

doi: 10.1111/tpj.16193pmid: 36932869

Fruit size and shape are controlled by genes expressed during the early developmental stages of fruit. Although the function of ASYMMETRIC LEAVES 2 (AS2) in promoting leaf adaxial cell fates has been well characterized in Arabidopsis thaliana, the molecular mechanisms conferring freshy fruit development as a spatial–temporal expression gene in tomato pericarp remain unclear. In the present study, we verified the transcription of SlAS2 and SlAS2L, two homologs of AS2, in the pericarp during early fruit development. Disruption of SlAS2 or SlAS2L caused a significant decrease in pericarp thickness as a result of a reduction in the number of pericarp cell layers and cell area, leading to smaller tomato fruit size, which revealed their critical roles in tomato fruit development. In addition, leaves and stamens exhibited severe morphological defects in slas2 and slas2l single mutants, as well as in the double mutants. These results demonstrated the redundant and pleiotropic functions of SlAS2 and SlAS2L in tomato fruit development. Yeast two‐hybrid and split‐luciferase complementation assays showed that both SlAS2 and SlAS2L physically interact with SlAS1. Molecular analyses further indicated that SlAS2 and SlAS2L regulate various downstream genes in leaf and fruit development, and that some genes participating in the regulation of cell division and cell differentiation in the tomato pericarp are affected by these genes. Our findings demonstrate that SlAS2 and SlAS2L are vital transcription factors required for tomato fruit development.

Yan, Wei; Yuan, Shuting; Zu, Yazhou; Chang, Zhenyi; Li, Yiqi; Chen, Zhufeng; Xie, Gang; Chen, Lei; Lu, Changqing; Deng, Xing Wang; Yang, Chengwei; Xu, Chunjue; Tang, Xiaoyan

doi: 10.1111/tpj.16194pmid: 36932862

Cold stress is a major factor limiting the production and geographical distribution of rice (Oryza sativa) varieties. However, the molecular mechanisms underlying cold tolerance remain to be elucidated. Here, we report that ornithine δ‐aminotransferase (OsOAT) contributes to cold tolerance during the vegetative and reproductive development of rice. osoat mutant was identified as a temperature‐sensitive male sterile mutant with deformed floral organs and seedlings sensitive to cold stress. Comparative transcriptome analysis showed that OsOAT mutation and cold treatment of the wild‐type plant led to similar changes in the global gene expression profiles in anthers. OsOAT genes in indica rice Huanghuazhan (HHZ) and japonica rice Wuyungeng (WYG) are different in gene structure and response to cold. OsOAT is cold‐inducible in WYG but cold‐irresponsive in HHZ. Further studies showed that indica varieties carry both WYG‐type and HHZ‐type OsOAT, whereas japonica varieties mostly carry WYG‐type OsOAT. Cultivars carrying HHZ‐type OsOAT are mainly distributed in low‐latitude regions, whereas varieties carrying WYG‐type OsOAT are distributed in both low‐ and high‐latitude regions. Moreover, indica varieties carrying WYG‐type OsOAT generally have higher seed‐setting rates than those carrying HHZ‐type OsOAT under cold stress at reproductive stage, highlighting the favorable selection for WYG‐type OsOAT during domestication and breeding to cope with low temperatures.

Bernoux, Maud; Chen, Jian; Zhang, Xiaoxiao; Newell, Kim; Hu, Jian; Deslandes, Laurent; Dodds, Peter

doi: 10.1111/tpj.16195pmid: 36932864

Recent work shed light on how plant intracellular immune receptors of the nucleotide‐binding leucine‐rich repeat (NLR) family are activated upon pathogen effector recognition to trigger immune responses. Activation of Toll‐interleukin‐1 receptor (TIR) domain‐containing NLRs (TNLs) induces receptor oligomerization and close proximity of the TIR domain, which is required for TIR enzymatic activity. TIR‐catalyzed small signaling molecules bind to EDS1 family heterodimers and subsequently activate downstream helper NLRs, which function as Ca2+ permeable channel to activate immune responses eventually leading to cell death. Subcellular localization requirements of TNLs and signaling partners are not well understood, although they are required to understand fully the mechanisms underlying NLR early signaling. TNLs show diverse subcellular localization while EDS1 shows nucleocytosolic localization. Here, we studied the impact of TIR and EDS1 mislocalization on the signaling activation of different TNLs. In Nicotiana benthamiana, our results suggest that close proximity of TIR domains isolated from flax L6 and Arabidopsis RPS4 and SNC1 TNLs drives signaling activation from different cell compartments. Nevertheless, both Golgi‐membrane anchored L6 and nucleocytosolic RPS4 have the same requirements for EDS1 subcellular localization in Arabidopsis thaliana. By using mislocalized variants of EDS1, we found that autoimmune L6 and RPS4 TIR domain can induce seedling cell death when EDS1 is present in the cytosol. However, when EDS1 is restricted to the nucleus, both induce a stunting phenotype but no cell death. Our data point out the importance of thoroughly investigating the dynamics of TNLs and signaling partners subcellular localization to understand TNL signaling fully.

Lee, Pei‐Fang; Zhan, Yong‐Xiang; Wang, Jou‐Chen; Cheng, Yen‐Hsuan; Hsu, Wei‐Han; Hsu, Hsing‐Fun; Chen, Wei‐Han; Yang, Chang‐Hsien

doi: 10.1111/tpj.16196pmid: 36932949

Ethylene‐responsive factors (ERFs) have diverse functions in the regulation of various plant developmental processes. Here, we demonstrate the dual role of an Arabidopsis ERF gene, AtERF19, in regulating reproductive meristem activity and flower organ size through the regulation of genes involved in CLAVATA–WUSCHEL (CLV–WUS) and auxin signaling, respectively. We found that AtERF19 stimulated the formation of flower primordia and controlled the number of flowers produced by activating WUS and was negatively regulated by CLV3. 35S::AtERF19 expression resulted in significantly more flowers, whereas 35S::AtERF19 + SRDX dominant‐negative mutants produced fewer flowers. In addition, AtERF19 also functioned to control flower organ size by promoting the division/expansion of the cells through activating Small Auxin Up RNA Gene 32 (SAUR32), which positively regulated MYB21/24 in the auxin signaling pathway. 35S::AtERF19 and 35S::SAUR32 resulted in similarly larger flowers, whereas 35S::AtERF19 + SRDX and 35S::SAUR32‐RNAi mutants produced smaller flowers than the wild type. The functions of AtERF19 were confirmed by the production of similarly more and larger flowers in 35S::AtERF19 transgenic tobacco (Nicotiana benthamiana) and in transgenic Arabidopsis which ectopically expressed the orchid gene (Nicotiana benthamiana) PaERF19 than in wild‐type plants. The finding that AtERF19 regulates genes involved in both CLV–WUS and auxin signaling during flower development significantly expands the current knowledge of the multifunctional evolution of ERF genes in plants. The results presented in this work indicate a dual role for the transcription factor AtERF19 in controlling the number of flowers produced and flower organ size through the regulation of genes involved in CLV–WUS and auxin signaling, respectively. Our findings expand the knowledge of the roles of ERF genes in the regulation of reproductive development.