Tiller Development Research Articles

Phytochrome B promotes blast disease resistance and enhances yield in rice.

Phytochromes are red/far-red light receptors that regulate various aspects of plant growth, development and stress responses. The precise mechanism by which Phytochrome B (PhyB)-mediated light signaling influences plant defense and development remains unclear. In this study, we showed that PhyB enhances rice (Oryza sativa) blast disease resistance, tillering, and grain size compared to wild-type plants. Notably, PhyB interacted with and degraded grassy tiller 1 (GT1), a negative regulator of tiller development. Knockdown of GT1 in a phyB background partially rescued the diminished tillering of phyB. However, GT1 negatively regulates rice resistance to blast, suggesting that PhyB degradation of GT1 promotes tillering but not blast resistance. Previously, PhyB was found to interact with and degrade phytochrome-interacting factor 15 (PIL15), a key regulator of seed development that reduces rice resistance to blast and seed size. pil15 mutation in phyB mutants rescued phyB seed size and blast resistance, suggesting that PhyB might interact with and degrade PIL15 to negatively regulate blast resistance and seed size. PIL15 directly activated sugar will be eventually exported transporter 2a (SWEET2a). sweet2a mutants were less susceptible to blast disease compared to wild type. Collectively, these data demonstrate that PhyB promotes rice yield and blast resistance by inhibiting the transcription factors GT1 and PIL15 and downstream signaling.

Effects of Compound Fertilizer and Branch Fertilizer on Population Construction and Yield of Machine-Transplanted Rice.

In order to study the effects of combined application of compound fertilizer and branch fertilizer on the growth and yield of machine-transplanted rice, four hybrid rice varieties were used as experimental materials, and four fertilization treatments were set up by completely random design: compound fertilizer (T0), compound fertilizer + conventional branch fertilizer (T1), compound fertilizer + (branch fertilizer - 20%) (T2), compound fertilizer + (branch fertilizer + 20%) (T3). The results showed that the branch fertilizer could effectively promote the early growth and rapid development of tillers, and increase the agronomic traits such as chlorophyll content, LAI and dry matter accumulation. Among the four varieties, the yield of the V4 variety was the highest under T3 treatment, which was 11,471.15 kg·hm-2, which was 37.34% higher than that of the control, and the yield increase effect was the most significant. The correlations showed that dry matter accumulation and LAI were significantly or highly significantly positively correlated with the number of effective spikes and yield, and the number of effective spikes was highly significantly positively correlated with the yield. In general, the application of pitchfork fertiliser increased the effective number of spikes and the number of grains per spike of each variety to different degrees, which effectively promoted the improvement of the rice yield.

Effect of kinetin on the tiller development in rice

Effect of kinetin on the tiller development in rice

The JA-OsJAZ6-DELLA module controls the tillering and drought stress response in rice

Jasmonic acid (JA) plays crucial functions during plant growth and stress response, but its roles and regulatory mechanism in plant branching remain largely unknown. Rice basal branching (tillering) is an essential agronomic trait that affects crop production. Here, we report that OsJAZ6, the repressor of JA signaling, negatively modulates rice tillering and drought stress tolerance. Loss-of-function mutants of OsJAZ6 exhibit a significant increase in tiller number, while OsJAZ6ΔJas-overexpression lines produce fewer tillers than wild-type plants. Further investigations show that function loss of OsJAZ6 promotes the tiller bud growth rather than formation. Mechanistic studies show that OsJAZ6 interacts with rice DELLA/SLR1 (SLENDER RICE 1), a transcription repressor of gibberellin (GA) signaling, and the interaction promotes SLR1 degradation, which further facilitates the degradation of rice tillering regulator MOC1 (MONOCULM 1), thereby inhibiting the tiller bud growth. In agreement, the slr1 mutant exhibits fewer tillers than wild type. Consistently, application of JA promotes the growth of tiller bud and thus increases the tiller number, while GA treatment results in opposite result. Meanwhile, osjaz6 mutants display enhanced drought tolerance, coupled with increased JA sensitivity, while the slr1 mutant shows the reverse behavior. Collectively, our data demonstrate that OsJAZ6 negatively modulates rice tillering as well as drought stress tolerance by destabilizing SLR1 protein. Our data shed light on the regulatory mechanism of controlling the tiller development and drought stress response in rice by the JA-OsJAZ6-SLR1 module.

Design and Fabrication of Solar Power Tiller

The present research focuses on the development of a solar-powered rotary tiller designed for primary and secondary soil cultivation. It explores the disparities between portable weeders and power tillers available in the Indian market. Various approaches to weed removal in crops are also examined. This study demonstrates that the majority of Indian farmers, particularly those with small-scale operations, can only afford portable weeders. Soil tillers and weeders are among the many agricultural mechanizations aimed at enhancing soil cultivation and weed management, particularly given that most farmers own small parcels of land. These tools notably reduce manual labor and are largely self-guided. The project operates on solar panels, utilizing their energy to power the machine, which operates the cutter or tiller. This innovation significantly saves time and expenses in field tasks, proving highly efficient for both tilling and weeding duties. Additionally, proposing the creation of high-capacity, energy-saving, adaptable machines, and integrated equipment aims to enhance labor efficiency, lower operational costs, improve punctuality, and render them suitable for customized leasing. Key Words: solar, power, tiller, weeder, farming, soil

Impact of Fe3O4-porphyrin hybrid nanoparticles on wheat: Physiological and metabolic advance

Iron-magnetic nanoparticles (Fe-NMPs) are widely used in environmental remediation, while porphyrin-based hybrid materials anchored to silica-coated Fe3O4-nanoparticles (Fe3O4-NPs) have been used for water disinfection purposes. To assess their safety on plants, especially concerning potential environmental release, it was investigated for the first time, the impact on plants of a silica-coated Fe3O4-NPs bearing a porphyrinic formulation (FORM) - FORM@NMP. Additionally, FORM alone and the magnetic nanoparticles without FORM anchored (NH2@NMP) were used for comparison. Wheat (Triticum aestivum L.) was chosen as a model species and was subjected to three environmentally relevant doses during germination and tiller development through root application. Morphological, physiological, and metabolic parameters were assessed. Despite a modest biomass decrease and alterations in membrane properties, no major impairments in germination or seedling development were observed. During tiller phase, both Fe3O4-NPs increased leaf length, and photosynthesis exhibited varied impacts: both Fe3O4-NPs and FORM alone increased pigments; only Fe3O4-NPs promoted gas exchange; all treatments improved the photochemical phase. Regarding oxidative stress, lipid peroxidation decreased in FORM and FORM@NMP, yet with increased O2-• in FORM@NMP; total flavonoids decreased in NH2@NMP and antioxidant enzymes declined across all materials. Phenolic profiling revealed a generalized trend towards a decrease in flavones. In conclusion, these nanoparticles can modulate wheat physiology/metabolism without apparently inducing phytotoxicity at low doses and during short-time exposure. Environmental implicationIron-magnetic nanoparticles are widely used in environmental remediation and fertilization, besides of new applications continuously being developed, making them emerging contaminants. Soil is a major sink for these nanoparticles and their fate and potential environmental risks in ecosystems must be addressed to achieve more sustainable environmental applications. Furthermore, as the reuse of treated wastewater for agricultural irrigation is being claimed, it is of major importance to disclose the impact on crops of the nanoparticles used for wastewater decontamination, such as those proposed in this work.

Physiological and Proteomic Analyses of mtn1 Mutant Reveal Key Players in Centipedegrass Tiller Development.

Tillering directly determines the seed production and propagation capacity of clonal plants. However, the molecular mechanisms involved in the tiller development of clonal plants are still not fully understood. In this study, we conducted a proteome comparison between the tiller buds and stem node of a multiple-tiller mutant mtn1 (more tillering number 1) and a wild type of centipedegrass. The results showed significant increases of 29.03% and 27.89% in the first and secondary tiller numbers, respectively, in the mtn1 mutant compared to the wild type. The photosynthetic rate increased by 31.44%, while the starch, soluble sugar, and sucrose contents in the tiller buds and stem node showed increases of 13.79%, 39.10%, 97.64%, 37.97%, 55.64%, and 7.68%, respectively, compared to the wild type. Two groups comprising 438 and 589 protein species, respectively, were differentially accumulated in the tiller buds and stem node in the mtn1 mutant. Consistent with the physiological characteristics, sucrose and starch metabolism as well as plant hormone signaling were found to be enriched with differentially abundant proteins (DAPs) in the mtn1 mutant. These results revealed that sugars and plant hormones may play important regulatory roles in the tiller development in centipedegrass. These results expanded our understanding of tiller development in clonal plants.

Unraveling the molecular mechanisms governing axillary meristem initiation in plants.

Axillary meristems (AMs) located in the leaf axils determine the number of shoots or tillers eventually formed, thus contributing significantly to the plant architecture and crop yields. The study of AM initiation is unavoidable and beneficial for crop productivity. Shoot branching is an undoubted determinant of plant architecture and thus greatly impacts crop yield due to the panicle-bearing traits of tillers. The emergence of the AM is essential for the incipient bud formation, and then the bud is dormant or outgrowth immediately to form a branch or tiller. While numerous reviews have focused on plant branching and tillering development networks, fewer specifically address AM initiation and its regulatory mechanisms. This review synthesizes the significant advancements in the genetic and hormonal factors governing AM initiation, with a primary focus on studies conducted in Arabidopsis (Arabidopsis thaliana L.) and rice (Oryza sativa L.). In particular, by elaborating on critical genes like LATERAL SUPPRESSOR (LAS), which specifically regulates AM initiation and the networks in which they are involved, we attempt to unify the cascades through which they are positioned. We concentrate on clarifying the precise mutual regulation between shoot apical meristem (SAM) and AM-related factors. Additionally, we examine challenges in elucidating AM formation mechanisms alongside opportunities provided by emerging omics approaches to identify AM-specific genes. By expanding our comprehension of the genetic and hormonal regulation of AM development, we can develop strategies to optimize crop production and address global food challenges effectively.

Genotypic responses to phosphorus and water management in winter wheat: Strategies to increase resource use efficiency and productivity

The phosphorus (P) addition can be helpful in the mitigation of the adverse effects of water deficit stress. However, the efficiency of wheat in utilizing both components has not been assessed in field conditions. This research aims to assess the effects of P and water addition on phosphorus use efficiency (PUE) and water productivity (WP) in field conditions for select wheat cultivars co-adapted to climate-induced agronomic challenges. Three wheat cultivars were selected based on their PUE and water WP from a previous experiment. The trials were conducted in field conditions over two consecutive years, from 2020 to 2021 (Season 1) and 2021–2022 (Season 2). The plants were grown on an andisol with a soil P concentration of 10 mg P kg−1 and 30 mg P kg−1. Two irrigation treatments were imposed: Well-watered (+W) and dryland (-W). The plants were sampled at three stages: tillering (Z25), anthesis (Z65), and ripening (Z95). At the end of the phenological cycle, grain yield components, grain yield, grain quality, PUE, and WP were evaluated. Phosphorus addition promotes plant growth, especially in the early vegetative stages, by enhancing tiller development and nutrient and water uptake. These effects were critical during the anthesis and ripening stages, enhancing yield components and higher grain production. Differential responses were observed across cultivars, underscoring the genotype-specificity in PUE and WP. Seasonal water deficit stress modulated these effects, highlighting a more complex genotype-environment-nutrient interaction. The water addition promoted PUE and WP, suggesting a synergy between the two components. Among the cultivars, Chevignon outperformed in grain yield, PUE, and WP. However, while phosphorus, water, and environmental factors influenced grain quality, the genetic background of the cultivar was the primary determinant of these components. This study advocates for implementing individual nutrient management strategies tailored to the specific cultivar and adaptable to environmental conditions under climate change.

Strigolactone and abscisic acid synthesis and signaling pathways are enhanced in the wheat oligo-tillering mutant ot1

Tiller number greatly contributes to grain yield in wheat. Using ethylmethanesulfonate mutagenesis, we previously discovered the oligo-tillering mutant ot1. The tiller number was significantly lower in ot1 than in the corresponding wild type from the early tillering stage until the heading stage. Compared to the wild type, the thousand-grain weight and grain length were increased by 15.41% and 31.44%, respectively, whereas the plant height and spike length were decreased by 26.13% and 37.25%, respectively. Transcriptomic analysis was conducted at the regreening and jointing stages to identify differential expressed genes (DEGs). Functional enrichment analysis with the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) databases showed differential expression of genes associated with ADP binding, transmembrane transport, and transcriptional regulation during tiller development. Differences in tiller number in ot1 led to the upregulation of genes in the strigolactone (SL) and abscisic acid (ABA) pathways. Specifically, the SL biosynthesis genes DWARF (D27), D17, D10, and MORE AXILLARY GROWTH 1 (MAX1) were upregulated by 3.37- to 8.23-fold; the SL signal transduction genes D14 and D53 were upregulated by 1.81- and 1.32-fold, respectively; the ABA biosynthesis genes 9-CIS-EPOXICAROTENOID DIOXIGENASE 3 (NCED3) and NCED5 were upregulated by 1.66- and 3.4-fold, respectively; and SNF1-REGULATED PROTEIN KINASE2 (SnRK2) and PROTEIN PHOSPHATASE 2C (PP2C) genes were upregulated by 1.30- to 4.79-fold. This suggested that the tiller number reduction in ot1 was due to alterations in plant hormone pathways. Genes known to promote tillering growth were upregulated, whereas those known to inhibit tillering growth were downregulated. For example, PIN-FORMED 9 (PIN9), which promotes tiller development, was upregulated by 8.23-fold in ot1; Ideal Plant Architecture 1 (IPA1), which inhibits tiller development, was downregulated by 1.74-fold. There were no significant differences in the expression levels of TILLER NUMBER 1 (TN1) or TEOSINTE BRANCHED 1 (TB1), indicating that the tiller reduction in ot1 was not controlled by known genes. Our findings provide valuable data for subsequent research into the genetic bases and regulatory mechanisms of wheat tillering.

Transcriptome analysis of axillary buds in low phosphorus stress and functional analysis of TaWRKY74s in wheat

BackgroundWheat is one of the main grain crops in the world, and the tiller number is a key factor affecting the yield of wheat. Phosphorus is an essential element for tiller development in wheat. However, due to decreasing phosphorus content in soil, there has been increasing use of phosphorus fertilizer, while imposing risk of soil and water pollution. Hence, it is important to identify low phosphorus tolerance genes and utilize them for stress resistance breeding in wheat.ResultsWe subjected the wheat variety Kenong 199 (KN199) to low phosphorus stress and observed a reduced tiller number. Using transcriptome analysis, we identified 1651 upregulated genes and 827 downregulated of genes after low phosphorus stress. The differentially expressed genes were found to be enriched in the enzyme activity regulation related to phosphorus, hormone signal transduction, and ion transmembrane transport. Furthermore, the transcription factor analysis revealed that TaWRKY74s were important for low phosphorus tolerance. TaWRKY74s have three alleles: TaWRKY74-A, TaWRKY74-B, and TaWRKY74-D, and they all belong to the WRKY family with conserved WRKYGQK motifs. These proteins were found to be located in the nucleus, and they were expressed in axillary meristem, shoot apical meristem(SAM), young leaves, leaf primordium, and spikelet primordium. The evolutionary tree showed that TaWRKY74s were closely related to OsWRKY74s in rice. Moreover, TaWRKY74s-RNAi transgenic plants displayed significantly fewer tillers compared to wild-type plants under normal conditions. Additionally, the tiller numebr of the RNAi transgenic plants was also significantly lower than that of the wild-type plants under low-phosphorus stress, and increased the decrease amplitude. This suggestd that TaWRKY74s are related to phosphorus response and can affect the tiller number of wheat.ConclusionsThe results of this research showed that TaWRKY74s were key genes in wheat response to low phosphorus stress, which might regulate wheat tiller number through abscisic acid (ABA) and auxin signal transduction pathways. This research lays the foundation for further investigating the mechanism of TaWRKY74s in the low phosphorus environments and is significant for wheat stress resistance breeding.

Transcriptional reprogramming of genes related to bud dormancy, outgrowth, and hormones for tiller development due to drought preconditioning in <i>Lolium perenne</i>

Transcriptional reprogramming of genes related to bud dormancy, outgrowth, and hormones for tiller development due to drought preconditioning in <i>Lolium perenne</i>

Determination of growth stages of some rice varieties as affected by sowing time

Identification of growth stages of rice is important for proper crop management and yield estimation. Appropriate planting time is a prerequisite for a decent harvest. The study aimed to determine the growth stages of different rice varieties and how they are affected by the sowing time. We evaluated four selected boro season rice varieties (BRRI dhan81, BRRI dhan86, BRRI dhan88, and BRRI dhan89) under five sowing times for growth stage study and yield following a completely randomized block design (RCBD) with three replications. Each variety showed considerable variation in different growth stages and yield at various sowing dates. All tested rice varieties took 40 days to reach the seedling stage on 15 December sowing. With the advancement or preceding this sowing date, the days required to attain this stage decreased. In mid-November sowing, the maximum period (33-34 days) was needed for tiller development and then reduced with the advancement of sowing dates irrespective of variety. Among the rice varieties, BRRI dhan89 required the highest time for panicle initiation (PI) on all sowing dates. The other three rice varieties took more or less similar time for panicle initiation. Among the rice varieties, BRRI dhan89 needed the highest, and BRRI dhan86 needed the lowest degree days for PI and flowering. BRRI dhan81 and BRRI dhan89 gave a higher grain yield from 15 November and 1 December sowing. BRRI dhan88 produced consistent grain yield throughout the sowing time. The fluctuations in PI stages' commencement indicate varietal characteristics, environmental conditions, and interaction between variety and environment. Bangladesh Rice J. 26 (2): 41-49, 2022

Large-scale RNAseq analysis provide a new insight into the critical genes and regulatory networks of tiller development mediated by gibberellin in sugarcane

Tillering plays a key role in sugarcane growth, development, and cane yield. Gibberellin (GA) and its biosynthesis inhibitor, paclobutrazol, have been used to manipulate the tiller production in sugarcane planting. However, the key genes and regulatory networks of sugarcane tiller development remain unclear. In this study, we applied GA3 and paclobutrazol to soak the sugarcane seeds for generating samples with varying tiller numbers. A total of 54 samples from multiple tissues of three tillering stages were employed for transcriptome sequencing using two full-length transcript isoform sequences datasets as reference. We observed significant downregulation of two genes within the GA metabolism pathway in response to the GA synthesis inhibitor. Additionally, we noted a substantial enrichment of genes associated with photosynthesis following treatment with GA3 or paclobutrazol. Using all the differentially expressed genes (DEGs) between each sample group, 41 gene modules were generated in the coexpression network. The associations between modules and traits were performed. The Gene Ontology (GO) enrichment, KEGG pathway enrichment, and hub genes analysis were implemented in the modules correlated with traits, especially, the modules correlated with GA3 content and tiller number were emphasized. Notably, the pathway of ubiquitin-mediated proteolysis were enriched in both the GA3 content positive correlated module and the tiller number negative correlated module, while an E3 ubiquitin ligase gene, RZFP34, was the top hub gene in these two modules, indicating the vital role of ubiquitin-mediated proteasomal degradation system in tillering regulation in sugarcane. Our study provides a comprehensive insight into regulatory networks involved in GA-mediated regulation of tiller development in sugarcane, which would lay the foundation of hormone regulation to promote sugarcane production.

Predicting corn tiller development in restrictive environments can be achieved to enhance defensive management decision tools for producers.

While globally appreciated for reliable, intensification-friendly phenotypes, modern corn (Zea mays L.) genotypes retain crop plasticity potential. For example, weather and heterogeneous field conditions can overcome phenotype uniformity and facilitate tiller expression. Such plasticity may be of interest in restrictive or otherwise variable environments around the world, where corn production is steadily expanding. No substantial effort has been made in available literature to predict tiller development in field scenarios, which could provide insight on corn plasticity capabilities and drivers. Therefore, the objectives of this investigation are as follows: 1) identify environment, management, or combinations of these factors key to accurately predict tiller density dynamics in corn; and 2) test outof-season prediction accuracy for identified factors. Replicated field trials were conducted in 17 diverse site-years in Kansas (United States) during the 2019, 2020, and 2021 seasons. Two modern corn genotypes were evaluated with target plant densities of 25000, 42000, and 60000 plants ha -1. Environmental, phenological, and morphological data were recorded and evaluated with generalized additive models. Plant density interactions with cumulative growing degree days, photothermal quotient, mean minimum and maximum daily temperatures, cumulative vapor pressure deficit, soil nitrate, and soil phosphorus were identified as important predictive factors of tiller density. Many of these factors had stark non-limiting thresholds. Factors impacting growth rates and photosynthesis (specifically vapor pressure deficit and maximum temperatures) were most sensitive to changes in plant density. Out-of-season prediction errors were seasonally variable, highlighting model limitations due to training datasets. This study demonstrates that tillering is a predictable plasticity mechanism in corn, and therefore could be incorporated into decision tools for restrictive growing regions. While useful for diagnostics, these models are limited in forecast utility and should be coupled with appropriate decision theory and risk assessments for producers in climatically and socioeconomically vulnerable environments.

High-low seedbed cultivation drives the efficient utilization of key production resources and the improvement of wheat productivity in the North China Plain

High-low seedbed cultivation (HLSC) is a key technique now used by smallholder and large farmers to increase the land utilization rate of wheat production in the North China Plain (NCP). However, little information is available on its superiority in crop productivity, resource utilization efficiency, and net return in comparison with flat cultivation (FC). A field experiment was conducted in the NCP in the 2020–2021 and 2021–2022 wheat seasons to determine whether HLSC would increase crop productivity, evapotranspiration (ET), intercepted photosynthetically active radiation (IPAR), crop nitrogen uptake and resource use efficiency. Two treatments were established, i.e., FC and HLSC, respectively. The results showed that HLSC significantly increased tiller development, leaf area index (LAI), and aboveground biomass compared with FC. Although HLSC did not increase ET relative to FC (P > 0.05), it increased IPAR by 5.5–6.6 % and grain nitrogen uptake by 12.1–12.6 % (P < 0.05). Pearson correlation analysis indicated that grain yield and biomass yield were regulated by the resource capture of wheat. Therefore, HLSC significantly increased grain yield by 14.5–18.3 % and net return by 45.4–59.3 % and enhanced the efficient use of resources by 13.2–15.6 % in water, 8.5–11.1 % in radiation, and 14.5–18.3 % in nitrogen compared with FC. HLSC is a promising planting system for improving crop productivity and resource use efficiency.

Minerals and chelated-based manganese fertilization influences the productivity, uptake, and mobilization of manganese in wheat (Triticum aestivum L.) in sandy loam soils.

Manganese (Mn) is an essential micronutrient in plants, and it is necessary for hydrolysis in photosystem II, chlorophyll biosynthesis, and also chloroplast breakdown. Limited Mn availability in light soil resulted in interveinal chlorosis, poor root development, and the development of fewer tillers, particularly staple cereals including wheat, while foliar Mn fertilizers were found efficient in improving crop yield as well as Mn use efficiency. In the above context, a study was conducted in consecutive two wheat growing seasons for screening of the most effective and economical Mn treatment for improving the yield and Mn uptake in wheat and to compare the relative effectiveness of MnCO3 against the recommended dose of MnSO4 for wheat. To fulfill the aims of the study, three manganese products, namely, 1) manganese carbonate MnCO3 (26% Mn w/w and 3.3% N w/w), 2) 0.5% MnSO4·H2O (30.5% Mn), and 3) Mn-EDTA solution (12% Mn), were used as experimental treatments. Treatments and their combinations were as follows: two levels of MnCO3 (26% Mn) @ 750 and 1,250 ml ha-1 were applied at the two stages (i.e., 25-30 and 35-40 days after sowing) of wheat, and three sprays each of 0.5% MnSO4 (30.5% Mn) and Mn-EDTA (12% Mn) solution were applied in other plots. The 2-year study showed that Mn application significantly increased the plant height, productive tillers plant-1, and 1,000 grain weight irrespective of fertilizer source. The results of MnSO4 for grain yield wheat as well as uptake of Mn were statistically at par with both levels (750 and 1,250 ml ha-1) of MnCO3 with two sprays at two stages of wheat. However, the application of Mn in the form of 0.5% MnSO4·H2O (30.5% Mn) was found more economical than MnCO3, while the mobilization efficiency index (1.56) was found maximum when Mn was applied in MnCO3 with two sprays (750 and 1,250 ml ha-1) in the two stages of wheat. Thus, the present study revealed that MnCO3 can be used as an alternative to MnSO4 to enhance the yield and Mn uptake of wheat.

Down-Regulation of Strigolactone Biosynthesis Gene D17 Alters the VOC Content and Increases Sogatella furcifera Infectivity in Rice

DWARF17 (D17/HTD1) is a well-defined rice strigolactone (SL) biosynthesis gene that influences rice tiller development and the production of rice. To investigate whether SLs play a role in the regulation of rice’s defense against the white-backed planthopper (WBPH, Sogatella furcifera), we compared a SL-biosynthetic defective mutant (d17) with WT rice plants. Our olfactory bioassay results revealed that WBPHs are attracted to d17 plants, which may be attributed to changes in rice volatile substances. Hexanal, a volatile substance, was significantly reduced in the d17 plants, and it was demonstrated that it repelled WBPHs at a concentration of 100 μL/L. Compared to the WT plants, WBPH female adults preferred to oviposit on d17 plants, where the egg hatching rate was higher. The transcript level analysis of defense-associated genes in the JA and SA pathways showed that the expression of OsJAmyb, OsJAZ8, OsPR1a and OsWRKY62 were significantly reduced in d17 plants compared to WT plants following WBPH infection. These findings suggest that silencing the strigolactone biosynthesis gene D17 weakens defenses against S. furcifera in rice.

Changes in the Growth and Yield of an Extremely Early-Maturing Rice Variety According to Transplanting Density

This study investigated the impact of transplanting density on the growth and yield characteristics of an extremely early-maturing rice variety that has a short vegetative growth period, as the limited growth period results in reduced tiller development and leads to a lower yield. The experiment was conducted in 2019 and 2020 at Chungcheongnam-do Agricultural Research and Extension Services in Republic of Korea, where various transplanting density treatments were tested using the Bbareumi rice variety with a vegetative growth period of less than 50 days. The results showed that the tiller number seedling−1 and spikelet number m−2 were influenced by the transplanting density and had a significant impact on the milled rice yield. Decreasing the tiller number seedling−1 by increasing the transplanting density led to an increase in the spikelet number m−2, which significantly improve the milled rice yield. Furthermore, the study identified the optimal transplanting density for maximizing yield as a transplanting distance of 30 × 12 cm, with 12 seedlings hill−1, which resulted in the highest milled rice yield of 5.64 ton/ha. These findings provide valuable insights for rice farmers and researchers regarding efforts to improve the cultivation practices of extremely early-maturing rice varieties.

OsPIN2 is involved in OsSPL14/17-inhibited tiller bud outgrowth in response to phosphate deficiency in rice

Phosphorus (P) is an essential nutrient for food crops. P-deficiency inhibits tiller development of rice; thus, an understanding of the P-modulated tiller development mechanism is crucial for grain yield. Auxin and strigolactones (SLs) have been implicated as regulators of tiller formation in rice. However, the relationships between the two in P-modulated tiller development are unclear. Here we found that low-P (LP) inhibited rice tiller formation and tiller bud elongation, with higher levels of SLs. The strong interaction between D53 (SL signaling repressor) and SPL14 and 17 (SPL14/17) inhibited their transcriptional activities under normal P (NP) condition, and mutations of SPL14/17 eliminated their inhibitory effects on tiller formation under LP condition, showing SPL14/17 act downstream of SLs signaling to inhibit tiller formation under P-deficiency in rice. Meanwhile, the expression levels of PIN2 were down-regulated under conditions of either LP and NP treated with GR24 when compared with NP condition, demonstrating SLs negative regulation of PIN2 transcription under LP condition. Further study showed that SPL14/17 inhibited the transcription expression of PIN2, and the knockout of PIN2 reduced tiller development by LP condition. Therefore, we presented that, under NP condition, bindings of D53 to SPL14/17 repress their transcriptional inhibition, reversing SPL14/17-inhibited PIN2 transcription and promoting tiller development. Proteasomal degradation of D53 releases SPL14/17, thus repressing PIN2 transcription and preventing production of tillering under LP condition.