Plants rely on systemic signalling mechanisms to establish whole-body defence in response to insect and nematode attacks. GLUTAMATE RECEPTOR-LIKE ( GLR ) genes have been implicated in long-distance transmission of wound signals to initiate the accumulation of the defence hormone jasmonate (JA) at undamaged distal sites. The systemic signalling entails the activation of Ca 2+ -permeable GLR channels by wound-released glutamate, triggering membrane depolarization and cytosolic Ca 2+ influx throughout the whole plant. The systemic electrical and calcium signals rapidly dissipate to restore the resting state, partially due to desensitization of the GLR channels. Here we report the discovery of calmodulin-mediated, Ca 2+ -dependent desensitization of GLR channels, revealing a negative feedback loop in the orchestration of plant systemic wound responses. A CRISPR-engineered GLR3.3 allele with impaired desensitization showed prolonged systemic electrical signalling and Ca 2+ waves, leading to enhanced plant defence against herbivores. Moreover, this Ca 2+ /calmodulin-mediated desensitization of GLR channels is a highly conserved mechanism in plants, providing a potential target for engineering anti-herbivore defence in crops.

STD1 specifically interacts with MAP65-5 in rice and they cooperatively control microtubule bundles in phragmoplast expansion during cell division. Microtubules play critical roles during the cell cycle progression in the plant cell. We previously reported that STEMLESS DWARF 1 (STD1), a kinesin-related protein, was localized specifically to the phragmoplast midzone during telophase to regulate the lateral expansion of phragmoplast in rice (Oryza sativa). However, how STD1 regulates microtubule organization remains unknown. Here, we found that STD1 interacted directly with MAP65-5, a member of the microtubule-associated proteins (MAPs). Both STD1 and MAP65-5 could form homodimers and bundle microtubules individually. Compared with MAP65-5, the microtubules bundled by STD1 were disassembled completely into single microtubules after adding ATP. Conversely, the interaction of STD1 with MAP65-5 enhanced the microtubule bundling. These results suggest STD1 and MAP65-5 might cooperatively regulate microtubule organization in the phragmoplast at telophase.

Inflorescence architecture is important for rice (Oryza sativa) grain yield. The phytohormone cytokinin (CK) has been shown to regulate rice inflorescence development; however, the underlying mechanism mediated by CK perception is still unclear. Employing a forward genetic approach, we isolated an inactive variant of the CK receptor OHK4/OsHK4 gene named panicle length1, which shows decreased panicle size due to reduced inflorescence meristem (IM) activity. A 2-amino acid deletion in the long α-helix stalk of the sensory module of OHK4 impairs the homodimerization and ligand-binding capacity of the receptor, even though the residues do not touch the ligand-binding domain or the dimerization interface. This deletion impairs CK signaling that occurs through the type-B response regulator OsRR21, which acts downstream of OHK4 in controlling inflorescence size. Meanwhile, we found that IDEAL PLANT ARCHITECTURE1(IPA1)/WEALTHY FARMER'S PANICLE (WFP), encoding a positive regulator of IM development, acts downstream of CK signaling and is directly activated by OsRR21. Additionally, we revealed that IPA1/WFP directly binds to the OHK4 promoter and upregulates its expression through interactions with 2 TCP transcription factors, forming a positive feedback circuit. Altogether, we identified the OHK4-OsRR21-IPA1 regulatory module, providing important insights into the role of CK signaling in regulating rice inflorescence architecture.

Rice inflorescence is one of the major organs in determining grain yield. The genetic and molecular regulation on rice inflorescence architecture has been well investigated over the past years. In the present review, we described genes regulating rice inflorescence architecture based on their roles in meristem activity maintenance, meristem identity conversion and branch elongation. We also introduced the emerging regulatory pathways of phytohormones involved in rice inflorescence development. These studies show the intricacies and challenges of manipulating inflorescence architecture for rice yield improvement.

分蘖是禾本科植物特有的分枝类型,是影响作物产量的关键因素之一.分枝/分蘖数由叶腋处侧生分生组织的数量和侧芽的活性共同决定.表观遗传修饰调控植物生长发育的各个方面,但是如何调控植物的分枝/分蘖数还未见系统报道.该综述归纳了表观遗传调控侧生分生组织的形成和侧芽向外生长两个方面,并展望了表观遗传在调控植物分枝/分蘖中的研究方向,以期为通过表观遗传修饰改良作物品种的育种途径提供理论指导.

Direct seeding (DS) of rice gained much attention due to labor scarcity and unavailability of water. However, reduced emergence and poor seedling establishment are the main problems of DS which causes significant yield losses. Herein, DS-associated seedling traits of three major rice groups, i.e., Indica (Ind), Japonica (Jap), and aus-type (Aus), were evaluated by using an improved mesocotyl elongation assay. The associations among different traits at the seedling and maturity stage were also studied. Significant variation was observed among the cultivars of different rice groups. The Aus group cultivars showed higher mean values for coleoptile (C, 3.85 cm), mesocotyl (MC, 4.17 cm), shoot length (SL, 13.64 cm), panicle length (PL, 23.44 cm), tillers number (T, 15.95), culm length (CL, 105.29 cm), and plant height (PH, 128.73 cm), while the Indica and Japonica groups showed higher mean values of grain length (GL, 8.69 mm), grain length/width ratio (GL/WR, 3.07), and grain width (GW, 3.31 mm), with 1000 grain weight (TGWt, 25.53 g), respectively. Pairwise correlation analysis showed that MC, C, and SL were positively correlated among themselves and with PL, CL, and PH. Moreover, based on principal component analysis (PCA), C, MC, SL, CL, and PH were identified as the major discriminative factors in the rice cultivars. This study describes the development of desired DS rice variety with long MC and semidwarf in height and suggests that Aus group cultivars can be used as the donor parents of favorable DS-associated traits in rice breeding programs.

Lateral branching is an important determinant of shoot architecture and crop yield. The plant hormone strigolactone （SL） inhibits lateral bud outgrowth in various plant species. Deficiencies in SL biosynthesis and signal transduction result in excessive outgrowth of lateral buds （Stirnberg et al., 2002; Sorefan et al., 2003）.

Leaf morphology influences photosynthesis, transpiration, and ultimately crop yield. However, the molecular mechanism of leaf development is still not fully understood. Here, we identified and characterized the narrow leaf21 (nal21) mutant in rice (Oryza sativa), showing a significant reduction in leaf width, leaf length and plant height, and increased tiller number. Microscopic observation revealed defects in the vascular system and reduced epidermal cell size and number in the nal21 leaf blade. Map-based cloning revealed that NAL21 encodes a ribosomal small subunit protein RPS3A. Ribosome-targeting antibiotics resistance assay and ribosome profiling showed a significant reduction in the free 40S ribosome subunit in the nal21 mutant. The nal21 mutant showed aberrant auxin responses in which multiple auxin response factors (ARFs) harboring upstream open-reading frames (uORFs) in their 5'-untranslated region were repressed at the translational level. The WUSCHEL-related homeobox 3A (OsWOX3A) gene, a key transcription factor involved in leaf blade lateral outgrowth, is also under the translational regulation by RPS3A. Transformation with modified OsARF11, OsARF16, and OsWOX3A genomic DNA (gDNA) lacking uORFs rescued the narrow leaf phenotype of nal21 to a better extent than transformation with their native gDNA, implying that RPS3A could regulate translation of ARFs and WOX3A through uORFs. Our results demonstrate that proper translational regulation of key factors involved in leaf development is essential to maintain normal leaf morphology.

Moderate leaf rolling is beneficial for leaf erectness and compact plant architecture. However, our understanding regarding the molecular mechanisms of leaf rolling is still limited. Here, we characterized a semi-dominant rice (Oryza sativa L.) mutant upward rolled leaf 1 (Url1) showing adaxially rolled leaves due to a decrease in the number and size of bulliform cells. Map-based cloning revealed that URL1 encodes the homeodomain-leucine zipper (HD-Zip) IV family member RICE OUTERMOST CELL-SPECIFIC 8 (ROC8). A single-base substitution in one of the two conserved complementary motifs unique to the 3'-untranslated region of this family enhanced URL1 mRNA stability and abundance in the Url1 mutant. URL1 (UPWARD ROLLED LEAF1) contains an ethylene-responsive element binding factor-associated amphiphilic repression motif and functions as a transcriptional repressor via interaction with the TOPLESS co-repressor OsTPL2. Rather than homodimerizing, URL1 heterodimerizes with another HD-ZIP IV member ROC5. URL1 could bind directly to the promoter and suppress the expression of abaxially curled leaf 1 (ACL1), a positive regulator of bulliform cell development. Knockout of OsTPL2 or ROC5 or overexpression of ACL1 in the Url1 mutant partially suppressed the leaf-rolling phenotype. Our results reveal a regulatory network whereby a transcriptional repression complex composed of URL1, ROC5, and the transcriptional corepressor TPL2 suppresses the expression of the ACL1 gene, thus modulating bulliform cell development and leaf rolling in rice.

Background Effective tiller number (ETN) has a pivotal role in determination of rice ( Oryza sativa L . ) grain yield. ETN is a complex quantitative trait regulated by both genetic and environmental factors. Despite multiple tillering-related genes have been cloned previously, few of them have been utilized in practical breeding programs. Results In this study, we conducted a genome-wide association study (GWAS) for ETN using a panel of 490 rice accessions derived from the 3 K rice genomes project. Thirty eight ETN-associated QTLs were identified, interestingly, four of which colocalized with the OsAAP1 , DWL2 , NAL1 , and OsWRKY74 gene previously reported to be involved in rice tillering regulation. Haplotype (Hap) analysis revealed that Hap5 of OsAAP1 , Hap3 and 6 of DWL2 , Hap2 of NAL1 , and Hap3 and 4 of OsWRKY74 are favorable alleles for ETN. Pyramiding favorable alleles of all these four genes had more enhancement in ETN than accessions harboring the favorable allele of only one gene. Moreover, we identified 25 novel candidate genes which might also affect ETN, and the positive association between expression levels of the OsPILS6b gene and ETN was validated by RT-qPCR. Furthermore, transcriptome analysis on data released on public database revealed that most ETN-associated genes showed a relatively high expression from 21 days after transplanting (DAT) to 49 DAT and decreased since then. This unique expression pattern of ETN-associated genes may contribute to the transition from vegetative to reproductive growth of tillers. Conclusions Our results revealed that GWAS is a feasible way to mine ETN-associated genes. The candidate genes and favorable alleles identified in this study have the potential application value in rice molecular breeding for high ETN and grain yield.

穗型是决定水稻(Oryza sativa)产量的关键因素之一.我们从粳稻品种圣稻808 (SD808)的EMS诱变突变体库中发现4份短穗突变体,这些突变体的穗长、一级枝梗数、二级枝梗数和穗粒数发生不同程度的降低.基因定位和图位克隆表明,这些突变体的表型受同一基因控制,将该基因命名为PAL3 (PANICLE LENGTH3).PAL3编码一个含12个跨膜结构域的多肽转运蛋白.pal3-1和pal3-2的点突变造成保守区域的氨基酸发生非同义突变;pal3-3的点突变造成第1外显子和内含子拼接错误;pal3-4的点突变造成蛋白翻译提前终止,导致第12个跨膜域缺失.对PAL3进行单倍型分析,共鉴定出9个单倍型(Hap1-Hap9),其中Hap1-Hap3为主要单倍型.Hap1以粳稻为主,Hap2同时包含籼稻和粳稻,Hap3则以籼稻为主.Hap1起源于普通野生稻(O.rufipogon),Hap2和Hap3可能起源于一年生普通野生稻(O.nivara).统计分析结果表明,Hap3的穗长显著高于Hap1和Hap2,其具有提高穗长的潜力.该研究揭示了多肽转运蛋白对水稻穗型的重要调控作用,为水稻穗型改良奠定了理论基础.

Background Grain size is a key agronomic trait that is directly associated with grain yield in rice. Although several genes related to grain size in rice have been identified, our understanding of the mechanism of grain development is still limited. Results In this study, we reported the characterization of a novel seed size mutant mini seed 2 ( mis2 ), in which the grain showed reduced length, width and thickness along with wrinkled surface. Microscopic analysis revealed that the spikelet epidermal cell size was reduced but the cell number was increased in the mis2 mutant, suggesting that MIS2 controls grain size by coordinately regulating epidermal cell size and cell number. Map-based cloning revealed that MIS2 encodes a receptor-like kinase CRINKLY4 (CR4) which showed the highest expression in developing panicles. The MIS2 protein is localized primarily on the plasma membrane along with the endosome. However, the Arg258Gln mutation located in extracellular domain in the mis2 mutant disturbed its subcellular localization. Additionally, three major haplotypes of MIS2 were identified in the japonica , indica and aus rice cultivars. The 18-bp InDel (insertion and deletion) in the 5′-UTR (untranslated region) caused different expression level of MIS2 in haplotypes. Conclusions We reported a key role of OsCR4 in controlling grain size and shape by coordinately regulating epidermal cell size and cell number. The Arg258 in the extracellular seven-repeat domain is essential for the correct subcellular behavior and function of the OsCR4 protein.

Bacillus licheniformis W10 is a strain of biocontrol bacteria that was obtained from plant rhizosphere screening. In this study, we purified, identified, and carried out bioinformatics analysis of the W10 antifungal protein from Bacillus licheniformis. Mass spectrometry analysis was carried out by passing the antifungal protein through a high-resolution time-of-flight mass spectrometer. Mascot searches of the tandem mass spectrometry data identified this antifungal protein as a serine protease, and the 1347 bp gene encoding this protein was cloned. Bioinformatics analysis of this protein indicated that it contains 448 amino acid residues, has a molecular weight of 48,794.16 Da and an isoelectric point of 6.04, and is a hydrophilic protein. In the secondary and tertiary structure of this protein, the proportion of α-helices and β-folds is similar, and the protein possesses a Peptidase_S8 conserved domain. Using BApNA as a substrate, it was found that the serine protease inhibitor phenylmethylsulfonyl fluoride (PMSF) can inhibit the W10 antifungal protein. PMSF concurrently reduced the inhibitory effects of the antifungal protein on Botrytis cinerea, showing that the W10 antifungal protein possesses serine protease activity. The W10 antifungal protein has good thermal stability. The study implies potential of this enzyme for biocontrol of fungal plant pathogens.

Gibberellins (GAs) are a group of endogenous phytohormones, playing important roles in plant growth and development. GA-induced interaction between the receptor GIBBERELLIN INSENSITIVE DWARF1 (GID1) and the DELLA repressor protein SLENDER RICE1 (SLR1) is critical to release GA signaling. In this study, a semi-dwarf mutant s1-1 was isolated from the rice variety Nipponbare (Oryza sativa, japonica) by EMS treatment, which exhibited significantly reduced internodes determining a dn-type dwarf pattern. GA-response experiments showed that the target gene in s1-1 is involved in GA signaling pathway. By mapping and sequencing, a novel GID1 allele with a single amino acid substitution from proline to leucine at the 158th position was identified in s1-1. GID1P158L could only interact with SLR1 at a high concentration of GA3 (10−5 M), but not at a low concentration (0 and 10−6 M). GID1P158L may reduce the degree of the interaction between GID1 and SLR1 at a physiological concentration of GA3, thereby contributing to the dwarf phenotype of s1-1. Our studies identified an important residue of GID1 required for GID1 and SLR1 interaction and provided a new semi-dwarf rice genetic resource.

Insect herbivory causes severe damage to plants and threatens the world's food production. During evolutionary adaptation, plants have evolved sophisticated mechanisms to rapidly accumulate a key defense hormone, jasmonate (JA), that triggers plant defense against herbivory. However, little is known about how plants initially activate JA biosynthesis at encounter with herbivory. Here, we uncover that a novel JAV1-JAZ8-WRKY51 (JJW) complex controls JA biosynthesis to defend against insect attack. In healthy plants, the JJW complex represses JA biosynthesis to restrain JA at a low basal level to ensure proper plant growth. When plants are injured by insect attack, injury rapidly triggers calcium influxes to activate calmodulin-dependent phosphorylation of JAV1, which disintegrates JJW complex and activates JA biosynthesis, giving rise to the rapid burst of JA for plant defense. Our findings offer new insights into the highly sophisticated defense systems evolved by plants to defend against herbivory.

Ubiquitin-mediated protein degradation plays an essential role in plant growth and development as well as responses to environmental and endogenous signals. F-box protein is one of the key components of the SCF (SKP1-CUL1-F-box protein) E3 ubiquitin ligase complex, which recruit specific substrate proteins for subsequent ubiquitination and 26S proteasome-mediated degradation to regulate developmental processes and signaling networks. However, it is not easy to obtain purified F-box proteins with high activity due to their unstable protein structures. Here, we found that Arabidopsis SKP-like proteins (ASKs) can significantly improve soluble expression of F-box proteins and maintain their bioactivity. We established an efficient ASK-assisted method to express and purify plant F-box proteins. The method meets a broad range of criteria required for the biochemical analysis or protein crystallization of plant F-box proteins.

穗型作为水稻(Oryza sativa)重要的农艺性状,近年来一直是研究热点.该文简要介绍了水稻穗部发育的一般过程,总结了近年来发现的调控水稻穗型相关基因,并根据水稻幼穗发育过程将其分为4类:分别调控枝梗分生组织的形成、枝梗分生组织的大小、小穗分生组织的转变时间以及枝梗的伸长;并概括分析了上述基因在调控水稻幼穗发育过程中所呈现出的路径关系.最后对水稻穗型遗传调控研究的未来发展方向进行了展望.

Plants have evolved complicated protective mechanisms to survive adverse conditions. Previously, we reported that the transcription factor OsbZIP46 regulates abscisic acid (ABA) signaling-mediated drought tolerance in rice (Oryza sativa) by modulating stress-related genes. An intrinsic D domain represses OsbZIP46 activity, but the detailed mechanism for the repression of OsbZIP46 activation remains unknown. Here, we report an OsbZIP46-interacting protein, MODD (Mediator of OsbZIP46 deactivation and degradation), which is homologous to the Arabidopsis thaliana ABSCISIC ACID-INSENSITIVE5 binding protein AFP. MODD was induced by ABA and drought stress, but the induction was much slower than that of OsbZIP46 In contrast to OsbZIP46, MODD negatively regulates ABA signaling and drought tolerance, and inhibits the expression of OsbZIP46 target genes. We found that MODD negatively regulates OsbZIP46 activity and stability. MODD represses OsbZIP46 activity via interaction with the OsTPR3-HDA702 corepressor complex and downregulation of the histone acetylation level at OsbZIP46 target genes. MODD promotes OsbZIP46 degradation via interaction with the U-box type ubiquitin E3 ligase OsPUB70. Interestingly, the D domain is required for both deactivation and degradation of OsbZIP46 via its interaction with MODD. These findings show that plants fine-tune their drought responses by elaborate regulatory mechanisms, including the coordination of activity and stability of key transcription factors.

Structural, biochemical, mass spectrometry and genetic analyses define Arabidopsis thaliana AtD14 as a non-canonical hormone receptor for strigolactone, which hydrolyses strigolactone into a covalently linked intermediate molecule and undergoes an open-to-closed state transition for interaction with D3 to trigger strigolactone signalling.

In order to understand the function ofSAHHinKalanchoe daigremontiana, a cDNA sequence, named asKdSAHH, was cloned by RT-PCR and RACE-PCR. The results showed that the full-length ofKdSAHHcDNA was 1748 bp, encoding 485 amino acids. The predicted molecular weight (MW) of KdSAHH was about 53 kDa with estimated pI of 5.59–5.682. The Scanprostie and DNAstar prediction showed that KdSAHH protein with two conserved motifs was very conservative in evolution. There were high homology between KdSAHH and SAHHs in other species by amino acid alignment, and which had the closest relationship with that inMedicago sativa. Lupinus luteusused as template, there were differences in three-dimensional structure of KdSAHH simulated by SWISS-MODLE and Phyre. These would lay out basis for research in expression and function of KdSAHH.