RGA1 regulates grain size, rice quality and seed germination in the small and round grain mutant srg5.

BACKGROUND: Generating elite rice varieties with high yield and superior quality is the main goal of rice breeding programs. Key agronomic traits, including grain size and seed germination characteristics, affect the final yield and quality of rice. The RGA1 gene, which encodes the α-subunit of rice G-protein, plays an important role in regulating rice architecture, seed size and abiotic stress responses. However, whether RGA1 is involved in the regulation of rice quality and seed germination traits is still unclear. RESULTS: In this study, a rice mutant small and round grain 5 (srg5), was identified in an EMS-induced rice mutant library. Systematic analysis of its major agronomic traits revealed that the srg5 mutant exhibited a semi-dwarf plant height with small and round grain and reduced panicle length. Analysis of the physicochemical properties of rice showed that the difference in rice eating and cooking quality (ECQ) between the srg5 mutant and its wild-type control was small, but the appearance quality was significantly improved. Interestingly, a significant suppression of rice seed germination and shoot growth was observed in the srg5 mutant, which was mainly related to the regulation of ABA metabolism. RGA1 was identified as the candidate gene for the srg5 mutant by BSA analysis. A SNP at the splice site of the first intron disrupted the normal splicing of the RGA1 transcript precursor, resulting in a premature stop codon. Additional linkage analysis confirmed that the target gene causing the srg5 mutant phenotype was RGA1. Finally, the introduction of the RGA1 mutant allele into two indica rice varieties also resulted in small and round rice grains with less chalkiness. CONCLUSIONS: These results indicate that RGA1 is not only involved in the control of rice architecture and grain size, but also in the regulation of rice quality and seed germination. This study sheds new light on the biological functions of RGA1, thereby providing valuable information for future systematic analysis of the G-protein pathway and its potential application in rice breeding programs.

Brassinosteroid regulates stomatal development in etiolated cotyledons via transcription factors BZR1 and BES1.

Brassinosteroids (BRs) are phytohormones that regulate stomatal development BRASSINAZOLE RESISTANT 1. In this study, we report that BR represses stomatal development in etiolated Arabidopsis (Arabidopsis thaliana) cotyledons via transcription factors BRASSINAZOLE RESISTANT 1 (BZR1) and bri1-EMS SUPPRESSOR1 (BES1), which directly target MITOGEN-ACTIVATED PROTEIN KINASE KINASE 9 (MKK9) and FAMA, two important genes for stomatal development. BZR1/BES1 bind MKK9 and FAMA promoters in vitro and in vivo, and mutation of the BZR1/BES1 binding motif in MKK9/FAMA promoters abolishes their transcription regulation by BZR1/BES1 in plants. Expression of a constitutively active MKK9 (MKK9DD) suppressed overproduction of stomata induced by BR deficiency, while expression of a constitutively inactive MKK9 (MKK9KR) induced high-density stomata in bzr1-1D. In addition, bzr-h, a sextuple mutant of the BZR1 family of proteins, produced overabundant stomata, and the dominant bzr1-1D and bes1-D mutants effectively suppressed the stomata-overproducing phenotype of brassinosteroid insensitive 1-116 (bri1-116) and brassinosteroid insensitive 2-1 (bin2-1). In conclusion, our results revealed important roles of BZR1/BES1 in stomatal development, and their transcriptional regulation of MKK9 and FAMA expression may contribute to BR-regulated stomatal development in etiolated Arabidopsis cotyledons.

Gene editing of non-coding regulatory DNA and its application in crop improvement.

The development of the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) system has provided precise and efficient strategies to edit target genes and generate transgene-free crops. Significant progress has been made in the editing of protein-coding genes; however, studies on the editing of non-coding DNA with regulatory roles lags far behind. Non-coding regulatory DNAs, including those which can be transcribed into long non-coding RNAs (lncRNAs), and miRNAs, together with cis-regulatory elements (CREs), play crucial roles in regulating plant growth and development. Therefore, the combination of CRISPR/Cas technology and non-coding regulatory DNA has great potential to generate novel alleles that affect various agronomic traits of crops, thus providing valuable genetic resources for crop breeding. Herein, we review recent advances in the roles of non-coding regulatory DNA, attempts to edit non-coding regulatory DNA for crop improvement, and potential application of novel editing tools in modulating non-coding regulatory DNA. Finally, the existing problems, possible solutions, and future applications of gene editing of non-coding regulatory DNA in modern crop breeding practice are also discussed.

Co-Overexpression of Two Key Source Genes, OsBMY4 and OsISA3, Improves Multiple Key Traits of Rice Seeds.

Optimized source-sink interactions are determinants of both rice yield and quality. However, most source genes have not been well studied in rice, a major grain crop. In this study, OsBMY4 and OsISA3, the key ß-amylase and debranching enzymes that control transient starch degradation in rice leaves, were co-overexpressed in rice in order to accelerate starch degradation efficiency and increase the sugar supply for sink organs. Systematic analyses of the transgenic rice indicated that co-overexpression of OsBMY4 and OsISA3 not only promoted rice yield and quality, but also improved seed germination and stress tolerance. Moreover, since the OsBMY4 gene has not been characterized, we generated osbmy4 mutants using CRIPSR/Cas9 gene editing, which helped to reveal the roles of ß-amylase in rice yield and quality. This study demonstrated that specific modulation of the expression of some key source genes improves the source-sink balance and leads to improvements in multiple key traits of rice seeds.

Genes and Their Molecular Functions Determining Seed Structure, Components, and Quality of Rice.

With the improvement of people's living standards and rice trade worldwide, the demand for high-quality rice is increasing. Therefore, breeding high quality rice is critical to meet the market demand. However, progress in improving rice grain quality lags far behind that of rice yield. This might be because of the complexity of rice grain quality research, and the lack of consensus definition and evaluation standards for high quality rice. In general, the main components of rice grain quality are milling quality (MQ), appearance quality (AQ), eating and cooking quality (ECQ), and nutritional quality (NQ). Importantly, all these quality traits are determined directly or indirectly by the structure and composition of the rice seeds. Structurally, rice seeds mainly comprise the spikelet hull, seed coat, aleurone layer, embryo, and endosperm. Among them, the size of spikelet hull is the key determinant of rice grain size, which usually affects rice AQ, MQ, and ECQ. The endosperm, mainly composed of starch and protein, is the major edible part of the rice seed. Therefore, the content, constitution, and physicochemical properties of starch and protein are crucial for multiple rice grain quality traits. Moreover, the other substances, such as lipids, minerals, vitamins, and phytochemicals, included in different parts of the rice seed, also contribute significantly to rice grain quality, especially the NQ. Rice seed growth and development are precisely controlled by many genes; therefore, cloning and dissecting these quality-related genes will enhance our knowledge of rice grain quality and will assist with the breeding of high quality rice. This review focuses on summarizing the recent progress on cloning key genes and their functions in regulating rice seed structure and composition, and their corresponding contributions to rice grain quality. This information will facilitate and advance future high quality rice breeding programs.

Brassinosteroids regulate rice seed germination through the BZR1-RAmy3D transcriptional module.

Seed dormancy and germination, two physiological processes unique to seed-bearing plants, are critical for plant growth and crop production. The phytohormone brassinosteroid (BR) regulates many aspects of plant growth and development, including seed germination. The molecular mechanisms underlying BR control of rice (Oryza sativa) seed germination are mostly unknown. We investigated the molecular regulatory cascade of BR in promoting rice seed germination and post-germination growth. Physiological assays indicated that blocking BR signaling, including introducing defects into the BR-insensitive 1 (BRI1) receptor or overexpressing the glycogen synthase kinase 2 (GSK2) kinase delayed seed germination and suppressed embryo growth. Our results also indicated that brassinazole-resistant 1 (BZR1) is the key downstream transcription factor that mediates BR regulation of seed germination by binding to the alpha-Amylase 3D (RAmy3D) promoter, which affects α-amylase expression and activity and the degradation of starch in the endosperm. The BZR1-RAmy3D module functions independently from the established Gibberellin MYB-alpha-amylase 1A (RAmy1A) module of the gibberellin (GA) pathway. We demonstrate that the BZR1-RAmy3D module also functions in embryo-related tissues. Moreover, RNA-sequencing (RNA-seq) analysis identified more potential BZR1-responsive genes, including those involved in starch and sucrose metabolism. Our study successfully identified the role of the BZR1-RAmy3D transcriptional module in regulating rice seed germination.

Effects of Interactive Dynamic Scalp Acupuncture on Motor Function and Gait of Lower Limbs after Stroke: A Multicenter, Randomized, Controlled Clinical Trial.

OBJECTIVE: To evaluate the effects of interactive dynamic scalp acupuncture (IDSA), simple combination therapy (SCT), and traditional scalp acupuncture (TSA) on motor function and gait of the lower limbs in post-stroke hemiplegia patients. METHODS: A total of 231 patients with post-stroke hemiplegia was randomly divided into IDSA (78 cases), SCT (78 cases), and TSA (75 cases) groups by a random number table. Scalp acupuncture (SA) and lower-limb robot training (LLRT) were both performed in the IDSA and SCT groups. The patients in the TSA group underwent SA and did not receive LLRT. The treatment was administered once daily and 6 times weekly for 8 continuous weeks, each session lasted for 30 min. The primary outcome measures included Fugl-Meyer assessment of the lower extremity (FMA-LE), berg balance scale (BBS), modified barthel index (MBI), and 6-min walking test (6MWT). The secondary outcome measures included stride frequency (SF), stride length (SL), stride width (SW), affected side foot angle (ASFA), passive range of motion (PROM) of the affected hip (PROM-H), knee (PROM-K) and ankle (PROM-A) joints. The patients were evaluated before treatment, at 1- and 2-month treatment, and 1-, and 2-month follow-up visits, respectively. Adverse events during 2-month treatment were observed. RESULTS: Nineteen patients withdrew from the trial, with 8 in the IDSA and 5 in the SCT groups, 6 in the TSA group. The FMA-LE, BBS, 6MWT and MBI scores in the IDSA group were significantly increased after 8-week treatment and 2 follow-up visits compared with the SCT and TSA groups (P<0.05 or P<0.01). Compared with pre-treatment, the grade distribution of BBS and MBI scores in the 3 groups were significantly improved at 1, 2-month treatment and 2 follow-up visits (P<0.05 or P<0.01). The SF, PROM-H, PROM-K and PROM-A in the IDSA group was significantly increased compared with the SCT and TSA groups after 8-week of treatment (P<0.05 or P<0.01). Compared with the SCT group, ASFA of the IDSA group was significantly reduced after 8-week of treatment (P<0.05). SF, SL, PROM-K and PROM-A were significantly increased at the 2nd follow-up visit whereas the ASFA was significantly reduced in the IDSA group compared with the SCT groups at 1st follow-up visit (P<0.05 or P<0.01). The SF was significantly increased in the SCT group compared with the TSA group after 8-week treatment (P<0.05). Compared with the TSA group, PROM-K, PROM-A were significantly increased at the 2nd follow-up visit (P<0.05). CONCLUSIONS: The effects of IDSA on lower-limb motor function and walking ability of post-stroke patients were superior to SCT and TSA. The SCT was comparable to TSA treatment, and appeared to be superior in improving the motion range of the lower extremities. (Registration No. ChiCTR1900027206).

Effect of Interactive Dynamic Scalp Acupuncture on Post-Stroke Cognitive Function, Depression, and Anxiety: A Multicenter, Randomized, Controlled Trial.

OBJECTIVE: To compare the clinical effects of interactive dynamic scalp acupuncture (IDSA), simple combination therapy (SCT), and traditional scalp acupuncture (TSA) on cognitive function, depression and anxiety in patients with post-stroke cognitive impairment. METHODS: A total of 660 patients with post-stroke cognitive impairment who were admitted to 3 hospitals in Shenzhen City between May 2017 and May 2020 were recruited and randomly assigned to the IDSA (218 cases), SCT (222 cases) and TSA groups (220 cases) according to a random number table. All the patients received conventional drug therapy for cerebral stroke and exercise rehabilitation training. Scalp acupuncture and computer-based cognitive training (CBCT) were performed simultaneously in the IDSA group, but separately in the morning and in the afternoon in the SCT group. The patients in the TSA group underwent scalp acupuncture only. The course of treatment was 8 weeks. Before treatment (M0), 1 (M1) and 2 months (M2) after treatment, as well as follow-up at 1 (M3) and 2 months (M4), the cognitive function of patients was assessed using the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment Scale (MoCA) Scales; depression, anxiety, sleep quality, and self-care ability of patients were assessed using Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), Pittsburgh Sleep Quality Index (PSQI), and Modified Barthel Index (MBI), respectively. During this trial, all adverse events (AEs) were accurately recorded. RESULTS: There were no significant differences in the MMSE, MoCA, HAMD, HAMA, PSQI, and MBI scores among the 3 groups at M0 (all P>0.05). In the IDSA group, the MMSE, MoCA and MBI scores from M2 to M4 were significantly higher than those in the SCT and TSA groups, while the HAMD, HAMA and PSQI scores were significantly reduced (all P<0.01). The changes of all above scores (M2-M0, M4-M0) were significantly superior to those in the SCT and TSA groups (all P<0.01, except M4-M0 of HAMD). At M2, the severity of MMSE, HAMD, HAMA, PSQI and MBI in the IDSA group was significantly lower than that in the SCT and TSA groups (all P<0.01). There was no serious AE during this trial. CONCLUSIONS: IDSA can not only significantly improve cognitive function, but also reduce depression, anxiety, which finally improves the patient's self-care ability. The effect of IDSA was significantly better than SCT and TSA. (Trial registration No. ChiCTR1900027206).

Glucan, Water-Dikinase 1 (GWD1), an ideal biotechnological target for potential improving yield and quality in rice.

The source-sink relationship determines the overall agronomic performance of rice. Cloning and characterizing key genes involved in the regulation of source and sink dynamics is imperative for improving rice yield. However, few source genes with potential application in rice have been identified. Glucan, Water-Dikinase 1 (GWD1) is an essential enzyme that plays a pivotal role in the first step of transitory starch degradation in source tissues. In the present study, we successfully generated gwd1 weak mutants by promoter editing using CRISPR/Cas9 system, and also leaf-dominant overexpression lines of GWD1 driven by Osl2 promoter. Analysis of the gwd1 plants indicated that promoter editing mediated down-regulation of GWD1 caused no observable effects on rice growth and development, but only mildly modified its grain transparency and seed germination. However, the transgenic pOsl2::GWD1 overexpression lines showed improvements in multiple key traits, including rice yield, grain shape, rice quality, seed germination and stress tolerance. Therefore, our study shows that GWD1 is not only involved in transitory starch degradation in source tissues, but also plays key roles in the seeds, which is a sink tissue. In conclusion, we find that GWD1 is an ideal biotechnological target with promising potential for the breeding of elite rice cultivars via genetic engineering.

[Scalp acupuncture combined with lower-limb intelligent feedback training for lower-limb motor dysfunction after stroke: a randomized controlled trial].

OBJECTIVE: To compare the efficacy of scalp acupuncture combined with lower-limb intelligent feedback training and lower-limb intelligent feedback training alone for lower-limb motor dysfunction after stroke. METHODS: A total of 154 patients with lower-limb motor dysfunction after stroke were randomly divided into an observation group (76 cases, 6 cases dropped off) and a control group (78 cases, 8 cases dropped off). The patients in both groups were treated with conventional medication and exercise rehabilitation training. In addition, the patients in the observation group were treated with scalp acupuncture combined with lower-limb intelligent feedback training. The scalp acupuncture was given at upper 1/5 of the anterior oblique line of parietal temporal area and upper 1/5 of the posterior oblique line of parietal temporal area. The patients in the control group were treated with lower-limb intelligent feedback training alone. All the treatment was given once a day, 6 days a week, totaling for 8 weeks. The affected-side lower-limb Brunnstrom stage and modified Ashworth scale (MAS) grade, 6-minute walk test (6MWT), Berg balance scale (BBS) score and modified Barthel index (MBI) score were evaluated before and after treatment in the two groups. The plantar pressure was measured by gait function evaluation system. RESULTS: Compared before treatment, the Brunnstrom stage in the two groups was improved after treatment (P<0.01); the MAS grade in the observation group was improved after treatment (P<0.01); the Brunnstrom stage and MAS grade in the observation group were superior to those in the control group (P<0.01, P<0.05). After treatment, the 6MWT, BBS and MBI scores in the two groups were increased (P<0.05), and those in the observation group were higher than those in the control group (P<0.05). After treatment, the touchdown area of health-side hind foot, affected-side front-hind foot and bilateral full foot in the observation group was increased (P<0.05), and the touchdown area of affected-side front-hind foot and full foot in the observation group was larger than that in the control group (P<0.05). The weight-bearing ratio of health-side forefoot and full foot in the observation group was decreased after treatment (P<0.05), and the weight-bearing ratio of affected-side forefoot, hind foot and full foot was increased after treatment (P<0.05). The weight-bearing ratio of health-side forefoot and full foot in the observation group was lower than that in the control group (P<0.05), and the weight-bearing ratio of health-side hind foot, affected-side forefoot and affected-side full foot in the observation group was higher than that in the control group (P<0.05). CONCLUSION: The scalp acupuncture combined with lower-limb intelligent feedback training could reduce the muscle tension of lower limbs, promote the separation movement mode of lower limbs, improve the plantar pressure distribution, and improve the balance ability and walking ability in stroke patients, and the curative effect is better than lower-limb intelligent feedback training alone.

[Interactive scalp acupuncture for cognitive dysfunction after stroke: a randomized controlled trial].

OBJECTIVE: To compare the efficacy of interactive scalp acupuncture, scalp acupuncture alone and scalp acupuncture plus cognitive training for cognitive dysfunction after stroke. METHODS: A total of 660 patients with cognitive dysfunction after stroke were randomly divided into an interactive scalp acupuncture group (218 cases, 18 cases dropped off), a scalp acupuncture group (220 cases, 20 cases dropped off) and a scalp acupuncture plus cognitive training group (222 cases, 22 cases dropped off). All the patients were treated with routine medication and exercise rehabilitation training. The interactive scalp acupuncture group was treated with scalp acupuncture on the parietal midline, and contralateral anterior parietal temporal oblique line and posterior parietal temporal oblique line at the same time of cognitive training; the scalp acupuncture group was treated with scalp acupuncture alone, and the scalp acupuncture plus cognitive training group was treated with scalp acupuncture and cognitive training in the morning and afternoon respectively. All the treatments were given once a day, 6 times a week for 8 weeks. Montreal cognitive assessment (MoCA) scale score was used to evaluate the cognitive function before treatment, 4 weeks and 8 weeks into treatment. RESULTS: Compared before treatment, the total score of MoCA was increased after 4-week treatment and 8-week treatment in the three groups (P<0.01), and the score in the interactive scalp acupuncture group was higher than that in the scalp acupuncture group and the scalp acupuncture plus cognitive training group (P<0.05, P<0.01). Compared before treatment, each item score of MoCA was increased after 8-week treatment in the three groups (P<0.01), and the score in the interactive scalp acupuncture group was higher than that in the scalp acupuncture group and the scalp acupuncture plus cognitive training group (P<0.01). Except for the attention, the remaining items scores of MoCA in the scalp acupuncture plus cognitive training group were higher than those in the scalp acupuncture group (P<0.01). CONCLUSION: The interactive scalp acupuncture could significantly improve the cognitive function in patients with cognitive dysfunction after stroke, and the efficacy is superior to scalp acupuncture alone and scalp acupuncture plus cognitive training.

Genome-Wide Identification and Expression Analysis of OsbZIP09 Target Genes in Rice Reveal Its Mechanism of Controlling Seed Germination.

Seed dormancy and germination are key events in plant development and are critical for crop production, and defects in seed germination or the inappropriate release of seed dormancy cause substantial losses in crop yields. Rice is the staple food for more than half of the world's population, and preharvest sprouting (PHS) is one of the most severe problems in rice production, due to a low level of seed dormancy, especially under warm and damp conditions. Therefore, PHS leads to yield loss and a decrease in rice quality and vitality. We reveal that mutation of OsbZIP09 inhibited rice PHS. Analysis of the expression of OsbZIP09 and its encoded protein sequence and structure indicated that OsbZIP09 is a typical bZIP transcription factor that contains conserved bZIP domains, and its expression is induced by ABA. Moreover, RNA sequencing (RNA-seq) and DNA affinity purification sequencing (DAP-seq) analyses were performed and 52 key direct targets of OsbZIP09 were identified, including OsLOX2 and Late Embryogenesis Abundant (LEA) family genes, which are involved in controlling seed germination. Most of these key targets showed consistent changes in expression in response to abscisic acid (ABA) treatment and OsbZIP09 mutation. The data characterize a number of key target genes that are directly regulated by OsbZIP09 and contribute to revealing the molecular mechanism that underlies how OsbZIP09 controls rice seed germination.

Gibberellin recovers seed germination in rice with impaired brassinosteroid signalling.

Seed germination is essential for ensuring grain yield and quality. Germination rate, uniformity, and post-germination growth all contribute to cultivation. Although the phytohormones gibberellin (GA) and brassinosteroid (BR) are known to regulate germination, the underlying mechanism of their crosstalk in co-regulating rice seed germination remains unclear. In this study, the isobaric tags for relative and absolute quantitation (iTRAQ) proteomic approach was employed to identify target proteins responsive to GA during recovery of germination in BR-deficient and BR-insensitive rice. A total of 42 differentially abundant proteins were identified in both BR-deficient and BR-insensitive plants, and most were altered consistently in the two groups. Gene Ontology (GO) analysis revealed enrichment in proteins with binding and catalytic activity. A potential protein-protein interaction network was constructed using STRING analysis, and five Late Embryogenesis Abundant (LEA) family members were markedly down-regulated at both mRNA transcript and protein levels. These LEA genes were specifically expressed in rice seeds, especially during the latter stages of seed development. Mutation of LEA33 affected rice grain size and seed germination, possibly by reducing BR accumulation and enhancing GA biosynthesis. The findings improve our knowledge of the mechanisms by which GA and BR coordinate seed germination.

Abscisic Acid Represses Rice Lamina Joint Inclination by Antagonizing Brassinosteroid Biosynthesis and Signaling.

Leaf angle is a key parameter that determines plant architecture and crop yield. Hormonal crosstalk involving brassinosteroid (BR) plays an essential role in leaf angle regulation in cereals. In this study, we investigated whether abscisic acid (ABA), an important stress-responsive hormone, co-regulates lamina joint inclination together with BR, and, if so, what the underlying mechanism is. Therefore, lamina joint inclination assay and RNA sequencing (RNA-Seq) analysis were performed here. ABA antagonizes the promotive effect of BR on leaf angle. Hundreds of genes responsive to both hormones that are involved in leaf-angle determination were identified by RNA-Seq and the expression of a gene subset was confirmed using quantitative real-time PCR (qRT-PCR). Results from analysis of rice mutants or transgenic lines affected in BR biosynthesis and signaling indicated that ABA antagonizes the effect of BR on lamina joint inclination by targeting the BR biosynthesis gene D11 and BR signaling genes GSK2 and DLT, thus forming a multi-level regulatory module that controls leaf angle in rice. Taken together, our findings demonstrate that BR and ABA antagonistically regulate lamina joint inclination in rice, thus contributing to the elucidation of the complex hormonal interaction network that optimizes leaf angle in rice.

iTRAQ-Based Analysis of Proteins Co-Regulated by Brassinosteroids and Gibberellins in Rice Embryos during Seed Germination.

Seed germination, a pivotal process in higher plants, is precisely regulated by various external and internal stimuli, including brassinosteroid (BR) and gibberellin (GA) phytohormones. The molecular mechanisms of crosstalk between BRs and GAs in regulating plant growth are well established. However, whether BRs interact with GAs to coordinate seed germination remains unknown, as do their common downstream targets. In the present study, 45 differentially expressed proteins responding to both BR and GA deficiency were identified using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis during seed germination. The results indicate that crosstalk between BRs and GAs participates in seed germination, at least in part, by modulating the same set of responsive proteins. Moreover, most targets exhibited concordant changes in response to BR and GA deficiency, and gene ontology (GO) indicated that most possess catalytic activity and are involved in various metabolic processes. Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analysis was used to construct a regulatory network of downstream proteins mediating BR- and GA-regulated seed germination. The mutation of GRP, one representative target, notably suppressed seed germination. Our findings not only provide critical clues for validating BR⁻GA crosstalk during rice seed germination, but also help to optimise molecular regulatory networks.

Down-Regulation of SSSII-2 Gene Expression Results in Novel Low-Amylose Rice with Soft, Transparent Grains.

Although soft rice, with low amylose content (AC), has high eating and cooking quality (ECQ), its appearance is poor due to the opaque endosperm. Here, a novel soft rice with low AC but a transparent appearance was generated by knocking-down the expression of SSSII-2, a gene encoding one isoform of soluble starch synthase (SSS). The physicochemical properties of the SSSII-2 RNAi rice are quite different from the control but more like the popular soft rice "Nanjing 46". The taste value assay further demonstrated that the ECQ of SSSII-2 RNAi rice was as high as "Nanjing 46", but only SSSII-2 RNAi rice retained the transparent endosperm under low moisture conditions. Further examination showed that the different morphologies and fine structures of the starch granules may contribute to the specific properties of SSSII-2 RNAi rice. Therefore, SSSII-2 has potential application in future high quality rice breeding programs.

Seed-Specific Expression of OsDWF4, a Rate-Limiting Gene Involved in Brassinosteroids Biosynthesis, Improves Both Grain Yield and Quality in Rice.

Brassinosteroids (BRs) are essential plant-specific steroidal hormones that regulate diverse growth and developmental processes in plants. We evaluated the effects of OsDWF4, a gene that encodes a rate-limiting enzyme in BR biosynthesis, on both rice yield and quality when driven by the Gt1 or Ubi promoter, which correspond to seed-specific or constitutive expression, respectively. Generally, transgenic plants expressing OsDWF4 showed increased grain yield with more tillers and longer and heavier seeds. Moreover, the starch physicochemical properties of the transgenic rice were also improved. Interestingly, OsDWF4 was found to exert different effects on either rice yield or quality when driven by the different promoters. The overall performance of the pGt1::OsDWF4 lines was better than that of the pUbi::OsDWF4 lines. Our data not only demonstrate the effects of OsDWF4 overexpression on both rice yield and quality but also suggest that a seed-specific promoter is a good choice in BR-mediated rice breeding programs.

The brassinosteroid-regulated transcription factors BZR1/BES1 function as a coordinator in multisignal-regulated plant growth.

BZR1 and BES1 are key transcription factors of brassinosteroid (BR) signaling and represent the integration node of numerous signaling cascades. Their direct target genes have been identified, and BZR1/BES1-DNA interactions have been experimentally verified. Importantly, BZR1/BES1 also integrate different growth and development events via direct protein-protein interactions. For instance, DELLAs, PIFs, ARF6, and PKL, all directly interact with BZR1/BES1, forming a BZR1/BES1-centered regulatory network to coordinate cell elongation. By dissecting various BZR1/BES1-mediated BR responses, the concept that BZR1/BES1 act as an integration hub in multisignal-regulated plant growth and development was developed. The regulation of BZR1/BES1 is dynamic and multifaceted, including phosphorylation status, activity, and stability. Moreover, certain epigenetic modification mechanisms are involved in BZR1/BES1's regulation of gene expression. Herein, we review recent advances in BZR1/BES1-mediated molecular connections between BR and other pathways, highlighting the central role of the BZR1/BES1 interactome in optimizing plant growth and development.