Panicle Size Research Articles

Genome-wide association study to identify chromosomal regions related to panicle architecture in rice (Oryza sativa)

Panicle architecture directly affects the grain yield of rice; meanwhile, crop domestication has increased the complexity of rice panicle size and branching pattern. Genome-wide association study (GWAS) was performed to investigate the genetic basis underlying panicle architecture using 183 rice accessions from around the world and a 7 K SNP array. Phenotyping was conducted at Texas A&M AgriLife Research Center in Beaumont, TX. GWAS was performed using MLM (Q + K) model using GAPIT software. At p-value < 0.001, a total of 49 GWAS QTLs controlling various panicle architecture traits were mapped. Considering the recurring and linked SNPs across the panicle architecture traits, 42 independent QTL regions were identified. Among these, 27 QTL regions co-localized with known genes or previously reported QTLs or significant SNP markers, while 15 were potentially novel QTL regions. The results of our study offer useful information on genetic bases controlling panicle architecture in rice, which could be further validated and utilized for designing markers for use in markers assisted selection (MAS) in rice breeding programs.

The LARGE2-APO1/APO2 regulatory module controls panicle size and grain number in rice.

Panicle size and grain number are important agronomic traits and influence grain yield in rice (Oryza sativa), but the molecular and genetic mechanisms underlying panicle size and grain number control remain largely unknown in crops. Here we report that LARGE2 encodes a HECT-domain E3 ubiquitin ligase OsUPL2 and regulates panicle size and grain number in rice. The loss of function large2 mutants produce large panicles with increased grain number, wide grains and leaves, and thick culms. LARGE2 regulates panicle size and grain number by repressing meristematic activity. LARGE2 is highly expressed in young panicles and grains. Biochemical analyses show that LARGE2 physically associates with ABERRANT PANICLE ORGANIZATION1 (APO1) and APO2, two positive regulators of panicle size and grain number, and modulates their stabilities. Genetic analyses support that LARGE2 functions with APO1 and APO2 in a common pathway to regulate panicle size and grain number. These findings reveal a novel genetic and molecular mechanism of the LARGE2-APO1/APO2 module-mediated control of panicle size and grain number in rice, suggesting that this module is a promising target for improving panicle size and grain number in crops.

CRISPR-based assessment of genomic structure in the conserved SQUAMOSA promoter-binding-like gene clusters in rice.

Although SQUAMOSA promoter-binding-like (SPL) transcription factors are important regulators of development in rice (Oryza sativa), prior assessments of the SPL family have been limited to single genes. A functional comparison across the full gene family in standardized genetic backgrounds has not been reported previously. Here, we demonstrate that the SPL gene family in rice is enriched due to the most recent whole genome duplication (WGD). Notably, 10 of 19 rice SPL genes (52%) cluster in four units that have persisted for at least 50 million years. We show that SPL gene grouping and retention following WGD is widespread in angiosperms, suggesting the conservatism and importance of this gene arrangement. We used Cas9 editing to generate transformation lines for all 19 SPL genes in a common set of backgrounds, and found that knockouts of 14 SPL genes exhibited defects in plant height, 10 exhibited defects in panicle size, and nine had altered grain lengths. We observed subfunctionalization of genes in the paleoduplicated pairs, but little evidence of neofunctionalization. Expression of OsSPL3 was negatively correlated with that of its closest neighbor in its synteny group, OsSPL4, and its sister paired gene, OsSPL12, in the opposing group. Nucleotide diversity was lower in eight of the nine singleton genes in domesticated rice, relative to wild rice, whereas the reverse was true for the paired genes. Together, these results provide functional information on eight previously unexamined OsSPL family members and suggest that paleoduplicate pair redundancy benefits plant survival and innovation.

Quantitative Analysis of Relationships Between Panicle Size and Fruit Traits in Litchi (Litchi chinensis Sonn.)

Quantitative Analysis of Relationships Between Panicle Size and Fruit Traits in Litchi (Litchi chinensis Sonn.)

Grain yield and N use efficiency of direct-seeded rice under different N management practices aimed to reduce N input

ABSTRACT The objective of this study was to determine whether integrated N management strategies can be used to increase yield and N use efficiency (NUE) of direct-seeded rice. Field experiments were conducted in the Chengdu Plain in China. Super hybrid, ordinary hybrid and inbred rice were grown under four N management practices, namely N0 (zero N), N1 (fix-timing N management), N2 (reduced basal N combined with SPAD-based N management [SBNM]), and N3 (no basal N fertilization combined with SBNM). Although total N application rate was 13%-40% lower under N2 and N3 than under N1, grain yield under N2 and N3 was equal to that under N1. Rice grown under N2 and N3 had higher NUE than under N1. Super hybrid rice had 11% higher grain yield than ordinary hybrid and inbred rice. The higher grain yields of super hybrid rice were attributed to higher biomass, larger panicle size and lower temperatures during grain filling period. Our results suggest that it is feasible to improve grain yield and NUE by growing rice under SBNM with a reduced basal N application rate, and that breeding cultivars with large panicle size may be an effective approach to achieve high yield in direct-seeded rice production.

Terminal drought effect on sugar partitioning and metabolism is modulated by leaf stay-green and panicle size in the stem of sweet sorghum (Sorghum bicolor L. Moench)

BackgroundThe benefits of leaf stay-green for maintaining grain filling in sorghum under drought was largely demonstrated. However, its role in the stability of a dual production (grain, stem sugar) in tall sweet sorghum remains to be elucidated. This study aimed to analyze the impact of a post-anthesis drought on sugar accumulation along stem internodes in sweet and tall West-African sorghum with variable leaf stay-green and grain yield abilities.MethodsFour accessions with similar phenology were studied in two consecutive years in the field at the National Agronomic Research Centre (CNRA) of Bambey (Senegal, West Africa) under two post-anthesis water treatments (irrigated, non-irrigated). Plant morphology, stem sugar related traits, grain production, and plant leaf area (PLA) variation were assessed. Carbohydrate contents (sucrose, hexoses, starch) were determined during grain filling in the whole stem juice and at three internode levels: bottom, median, top. Analysis of variance was performed to test post-anthesis water treatment, accession, organ, year effects and their interactions on the studied traits.ResultsPanicle dry weight (PDW) was not affected by drought, but strongly varied among years and accessions. The PDW/PLA ratio was negatively correlated with the variation of sucrose and hexoses at the three internodes levels. This carbohydrates reduction was mainly influenced by the PDW. The bigger the panicle the higher the carbohydrates remobilization from the stem to panicle for grain filling. This was mainly shown on accessions G3 and G11 which exhibited low stay green ability. However, G10 with low PDW/PLA ratio and showing higher stay green ability, exhibited a low reduction of total soluble sugars and sucrose and inversely higher increase of hexoses mainly at the median internode.ConclusionsThis ability to better maintain green leaf area and high hexoses in the stem under post-flowering drought could be an osmoregulation mechanism to adapt to drought. Therefore, stay-green is an important trait to consider for sweet sorghum breeding and particularly in the objective of developing dual purpose varieties in drought prone environments.

Rice gene, OsCKX2-2, regulates inflorescence and grain size by increasing endogenous cytokinin content

Panicle size is one of the yield determining traits in rice (Oryza sativa L.). In the current study, a rice mutant named cytokinin oxidase/dehydrogenase (Osckx2-2) was developed from the indica cultivar 9311 by ethyl methanesulfonate (EMS) mutagenesis. A comparison of agronomic traits showed that the panicle of the Osckx2-2 mutant was longer with dense branching pattern and higher seed setting rate compared to the wild-type (WT). In addition, the grains in the Osckx2-2 mutant were markedly longer, wider, and heavier compared to the WT. Histological analysis revealed that a higher number of the spikelet cells with bigger size resulted in larger grains in the Osckx2-2 mutant. By map-based cloning, SNP was detected in the 3′-UTR of the OsCKX2-2 gene which encodes cytokinin dehydrogenase and the cleaved amplified polymorphic sequence (CAPS) marker was developed based on the detected SNP. The RT-qPCR analysis displayed a decreased OsCKX2-2 expression in the Osckx2-2 mutant panicles. Meanwhile, the enzymatic activity assay showed the reduced cytokinin dehydrogenase enzyme activity, whereas the enzyme-linked immunosorbent assay (ELISA) revealed remarkably higher endogenous cytokinin content in the Osckx2-2 mutant in contrast to WT. The analysis of grain quality parameters showed that the degree of chalkiness and gel consistency decreased, while the amylose content and alkaline spreading value increased in the Osckx2-2 mutant. The OsCKX2-2 gene and Osckx2-2 mutant would be beneficial in marker-assisted backcrossing to improve yield in rice.

Morphological characterization and genetic identity of crop wild relatives of rice (Oryza sativa L.) collected from different ecological niches of India

Crop wild relatives of rice (Oryza sativa L.) are an important reservoir of genes for broadening the genetic base of commercial varieties. India is the centre of genetic diversity of some of the wild as-well-as the cultivated rice species. In order to collect genetic diversity, explorations were undertaken in six states located in different agro-ecological zones of India. Forty-four accessions belonging to four wild species (Oryza rufipogon Griff., Oryza nivara Sharma et Shastry, Oryza officinalis Wall. ex Watt and Oryza sativa L. f. spontanea Roshev.) including two accessions of cultivated rice (Oryza sativa L. subsp. indica Kato) were collected from different ecological niches. The rice accessions were characterized using 28 morphological descriptors, which included 15 qualitative and 13 quantitative traits. Wild rice accessions displayed a broad range of phenotypic variation for plant height, main heading days, days to 50% flowering, flag-leaf length and width, panicle shape and size, peduncle length, awning pattern, awn length and colour, seed length and width, seed length/width ratio and 100-seed weight. Cluster analysis based on Jaccard’s similarity coefficients derived from 28 morphological traits grouped 44 accessions into three clades. DNA sequencing revealed that internal transcribed spacer (ITS) region of 18S–5.8S–28S nuclear ribosomal cistron varied from 574 to 577 bp with mean of 576.1 bp in AA-genome species. GC content was high in ITS region, which varied from 69.57 to 70.36% with mean value of 69.99%. Neighbour-joining phylogenetic tree distinguished Oryza sativa–nivara–rufipogon complex from other species of AA-genome. The wild germplasm characterized in this study could be utilized in the genetic enhancement of cultivated rice.

EFFECTS OF SILICON AND SEED MICROBIOLIZATION WITH BACILLUS METHYLOTROPHICUS AGAINST LEAF SPOT (CURVULARIA LUNATA) IN RICE

The objective of the research was to evaluate the effect of the silicified fertilization of the seeds microbiolization with B. methylotrophicus in the control of leaf spot caused by C. lunata and in the factors of rice production. The experiment was carried out in a greenhouse, in a completely randomized design, in a 5 x 2 factorial arrangement, with five doses of silicon (0.0, 1.0, 2.0, 4.0 and 6.0 t ha 1) and microbiolized and non-microbiolized seeds, with five repetitions. The leaf spot was evaluated at 7, 14 and 21 days after inoculation of the pathogen, considering total number of leaves, number of healthy and diseased leaves per vase, percentage of diseased leaves, size of lesion and control. The photosynthetic rates and chlorophyll indexes in rice leaves were also measured before and after inoculation of the pathogen. At the end of the crop cycle, the size and number of panicles per pot, the grains number, the number of full grains and pips per panicle and the dry plant mass were evaluated. There was an effect of the doses of agrosilicon in the control of leaf spot and in the reduction of the number and percentage of diseased leaves. However, no effect of seed microbiolization was observed on leaf spot control as well as rice production factors.

Cover Image: Local auxin biosynthesis in rice

The cover shows a rice deficiency mutant in local auxin biosynthesis. In this issue, Guo et al. (581–600) report a rice tsg1 mutant which has more tillers but a smaller panicle and grain size resulting from a reduction in endogenous auxin. TSG1 encodes a tryptophan aminotransferase localized at the endoplasmic reticulum with remarkable aminotransferase activity. TSG1 dominates the tryptophan aminotransferase family of rice, playing a prominent role in local auxin biosynthesis.

Mutagenic effect of ethyl methane sulfonate (EMS) on barnyard millet (Echinochloa frumentaceae) variety CO(KV)2

Barnyard millet variety CO (KV) 2 was treated with 2 different doses of EMS (Ethyl Methane Sulfonate) (ie. 0.2%, 0.4%, 0.6%, 0.8% and 1.0%). Six days after treatment germination percentage was calculated and LD50 value were fixed as 0.51%EMS. M1 population was raised with two treatments 04% and 0.5%. Seedlings with normal growth and development were observed in 0.4% EMS dose and very poor establishment, stunted growth and 80% spikelet sterility was observed in 0.5% EMS treatment. In M2 generation macro-mutants such as plant type, earliness, study stem, bigger panicle size and higher plant yield (28g/plant) were obtained.

Production of novel beneficial alleles of a rice yield-related QTL by CRISPR/Cas9.

Production of novel beneficial alleles of a rice yield-related QTL by CRISPR/Cas9.

Semantic Segmentation of Sorghum Using Hyperspectral Data Identifies Genetic Associations.

This study describes the evaluation of a range of approaches to semantic segmentation of hyperspectral images of sorghum plants, classifying each pixel as either nonplant or belonging to one of the three organ types (leaf, stalk, panicle). While many current methods for segmentation focus on separating plant pixels from background, organ-specific segmentation makes it feasible to measure a wider range of plant properties. Manually scored training data for a set of hyperspectral images collected from a sorghum association population was used to train and evaluate a set of supervised classification models. Many algorithms show acceptable accuracy for this classification task. Algorithms trained on sorghum data are able to accurately classify maize leaves and stalks, but fail to accurately classify maize reproductive organs which are not directly equivalent to sorghum panicles. Trait measurements extracted from semantic segmentation of sorghum organs can be used to identify both genes known to be controlling variation in a previously measured phenotypes (e.g., panicle size and plant height) as well as identify signals for genes controlling traits not previously quantified in this population (e.g., stalk/leaf ratio). Organ level semantic segmentation provides opportunities to identify genes controlling variation in a wide range of morphological phenotypes in sorghum, maize, and other related grain crops.

Seasonal changes in crop growth and grain yield of different japonica rice cultivars in southeast China

AbstractIt is unknown whether japonica rice bred up in the single season is suitable for growing in the late season in southeastern China. To evaluate the response of grain yield and growth traits of japonica varieties to the changing growing season, two types of japonica rice (inbred japonica and indica‐japonica hybrid rice) were planted during single and late seasons in 2016 and 2017. The grain yields of indica‐japonica hybrid rice were 8.3–9.5 t ha−1 and 9.2–10.8 t ha−1 in the late and single season, respectively, which were significantly greater than those of japonica inbred rice. In addition, the grain yields decreased when the growing season was switched from the single to the late season, being 17.3–23.7% for the inbred japonica rice and 4.0–9.7% for the indica‐japonica hybrid rice, indicating a small yield gap between the single and late season of the indica‐japonica hybrid rice. Furthermore, the indica‐japonica hybrid rice had a higher accumulated biomass, leaf area index (LAI), and spikelets per panicle; comparable phenological traits and leaf photosynthetic rate during panicle development; but lower grain weight and grain filling percentage compared with those of the inbred japonica rice. These results suggested that high grain yield of the indica‐japonica hybrid rice during the late season might be attributed to the high accumulation of biomass and the large panicle size. Thereby, we suggested that the great LAI during panicle development, high biomass accumulation before heading, and large panicle size might be useful as indicators for breeding the japonica variety during the late season.

EFFECTS OF AZOLLA BIOMASS GROWTH ON FLOOD WATER TEMPERATURE AND PH, TILLERING AND YIELD OF PADDY RICE

&lt;p&gt;&lt;em&gt;Azolla&lt;/em&gt; is a floating pteridophyte, which forms an association with an endosymbiont, the nitrogen-fixing cyanobacterium &lt;em&gt;Anabaena azollae&lt;/em&gt;. In Mwea Irrigation Scheme paddies, &lt;em&gt;Azolla&lt;/em&gt; biomass coverage ranges from 25 to 50 % with a high biomass growth rate and this has caused a challenge in its management. Knowledge on the effect of &lt;em&gt;Azolla&lt;/em&gt; biomass on rice tillering, root development and grain yield are important in order to exploit its potential benefits in Mwea Irrigation Scheme, where nearly 60 % of the total rice in Kenya is produced. The effect of &lt;em&gt;Azolla&lt;/em&gt; on tillering, plant biomass, adventitious roots development, basal internode growth and yield of rice, was studied during 2015/2016 short and long rains. &lt;em&gt;Azolla&lt;/em&gt; was inoculated in 30 cm x 30 cm plastic pots planted with rice variety Basmati 370. Controls where no &lt;em&gt;Azolla&lt;/em&gt; was inoculated were included. Tiller number, plant height, flood water temperature and pH were determined at 21, 32, 42, 60 and 75 days after transplanting (DAT). At 120 DAT, grain yield and yield components were determined. Length of basal node and adventitious root were measured and dry biomass weights of, root and above ground biomass determined. Water temperature in &lt;em&gt;Azolla&lt;/em&gt; inoculated pots were significantly lower than in controls by 0.8 °C and 1.3 °C in the second and first seasons respectively with a daily fluctuation of 2 °C. The pH of flood water in potted rice inoculated with &lt;em&gt;Azolla&lt;/em&gt; was significantly lower than in control. &lt;em&gt;Azolla&lt;/em&gt; inoculated potted rice had significantly higher number of tillers/m&lt;sup&gt;2&lt;/sup&gt;, spikelets per panicle&lt;sup&gt;-1&lt;/sup&gt;, panicle size m&lt;sup&gt;-2&lt;/sup&gt;, 1000 grain weight and plant biomass than in non-inoculated controls. Adventitious roots were significantly longer and more per unit area in all treatments than in controls. The basal stem node length was significantly shorter while root biomass was less for the &lt;em&gt;Azolla&lt;/em&gt; inoculated potted rice than in controls. In all treatments, &lt;em&gt;Azolla&lt;/em&gt; doubled its biomass within an average of 5 days.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Fine mapping and grain yield analysis of a major QTL controlling primary branch number in rice (Oryza sativa L.)

Panicle size is one of the most important agronomic traits highly associated with grain yield in rice. For quantitative trait locus (QTL) analysis and breeding utilization of panicle size in rice, a large panicle rice line YR1 was used as a donor to cross and backcross with a commercial cultivar Ningjing 1 (NJ1), and developed backcross populations. In a BC2F2 population, a total of 3 QTL associated with panicle size were found on chromosome 1 and 8. Two of the QTLs, qPBN1 and qGNP1, were mapped to an interval on chromosome 1, where a previously cloned gene GN1a was located. qPBN8, a major QTL for primary branch number on chromosome 8, was finally narrowed to a 51.8 kb region, containing reported gene OsSPL14 regulating branch number and plant architecture. Through sequence and expression comparison, the qPBN8 was considered to be the allele of OsSPL14. The investigation of yield structure in six pairs of near-isogenic lines revealed that the effects of qPBN8 on grain yield were related to the length of vegetative period. The qPBN8 allele of large panicle was suitable for late-maturing varieties to improve yield.

Development of a large population of activation‐tagged mutants in an elite indica rice variety

AbstractIn this study, we have generated more than 12,000 activation‐tagged mutants in a high‐yielding indica rice variety, 'BPT 5204', employing maize Ac/Ds system. Different transgenic plants obtained were analysed based on expression patterns of green fluorescence protein (GFP), red fluorescence protein (RFP), herbicide (Basta) tolerance and molecular analyses. T1 seeds of pSQ5 and pSQ5‐bar transgenics, when germinated separately on hygromycin (50 mg/L) and phosphinothricin (5 mg/L) containing medium, revealed a segregation of 3 tolerant : 1 susceptible plants. The germinal transposition frequency of Ds element in different T2 progeny of rice plants was found to be about 18.0%. Different stable tagged mutants exhibited marked increases in plant height, number of tillers, leaf size, panicle size, seed size and number of grains per plant. The overall results indicate that the genes associated with these traits are upregulated by the enhancer element in activation‐tagged mutants. As such, the various tagged mutant lines appear promising and serve as a valuable genetic resource for identification of key genes determining different agronomic traits of rice.

Printed sowing improves grain yield with reduced seed rate in machine-transplanted hybrid rice

Machine transplanting is an alternative establishment method to replace manual transplanting that reduces labor inputs in rice production. It is important to reduce the seed rate in mechanical transplanting, especially for hybrid rice with expensive seeds. Printed sowing (PS), i.e. pasting seeds to paper, is a new sowing method for reducing the seed rate. This study was conducted to compare seed rate, grain yield, and yield attributes in machine-transplanted hybrid rice between PS and manual sowing (MS). Field experiments were conducted in the early and late seasons of 2017 and 2018 in Yongan Town, Hunan Province, China. Seed rates under PS were 9.6–19.8 kg ha–1, which were lower by 2.73–5.65 times than under MS. PS produced 11 % higher grain yield compared to MS. The higher grain yields under PS compared to MS were mainly due to higher seedling quality, larger panicle size, higher spikelet filling percentage, higher aboveground biomass, and higher harvest index under PS than under MS. The better performance of yield attributes under PS compared to MS could be explained by improvements in morphological and physiological traits including number of vascular bundles and leaf photosynthetic capacity. Our study suggests that PS is a feasible method to reduce seed rate and increase grain yield in machine-transplanted hybrid rice production.

Effects of elevated CO2 concentration on grain filling capacity and quality of rice grains located at different positions on a panicle.

The rising atmospheric CO2 concentration affects spikelets development, grain filling process, and rice quality. However, it is unclear that whether such effects are related to grain positions on rice panicle. By using a rice FACE (Free-Air CO2 Enrichment) platform, we grew a japoni-ca rice cultivar Wuyunjing 23, characterized with high yield and good quality, under ambient (Ambient) and elevated CO2 concentrations (+200 μmol·mol-1, FACE). The effects of increased CO2 concentration on spikelet density, grain filling capacity, the appearance and eating quality of rice grains were examined and the association of such effects with grain positions on rice panicle were investigated. The results showed that CO2 enrichment increased grain yield of Wuyunjing 23 by 18.3%. The panicle number per unit land area and filled-grain weight increased by 21.4% and 9.4%, respectively; whereas the number of spikelets per panicle and filled-grain percentage decreased by 9.0% and 2.2%, respectively. The decreased filled-grain percentage of rice grown under FACE treatment was mainly related to the increases of empty-grain percentage in all parts of rice panicle. The decrease of rice spikelets number per panicle by FACE treatment was mainly due to the substantial decrease of surviving spikelets of secondary branches in upper and middle parts of rice panicles instead of other positions. The CO2-induced changes of filled-grain weight and filled-grain percentage were similar among grains located at different positions on rice panicle. FACE treatment reduced the green grain rate and increased the grain length and width, with the grains at different positions on rice papnicle showing similar responses. FACE significantly increased chalky grain percentage by 59% and chalkiness degree by 55%, with the increases for both parameters following the order of primary branches＞secondary branches and upper part＞middle part＞lower part. FACE treatment slightly increased amylose content while decreased peak viscosity, hot viscosity, breakdown, final viscosity and setback, but most of these effects were nonsignificant. The gelatinization temperature of rice also reduced by 5% under FACE, and the decrease of inferior spikelets was greater than that of superior spikelets. In summary, the yield increase of Wuyunjing 23 under high CO2 concentration was mainly related to the increases of panicle number and individual grain weight, while the panicle size was reduced. Elevated CO2 concentration reduced green grain percentage but increased grain chalkiness, and had little effect on cooking and eating quality. The grain positions on rice panicle affected the responses of spikelets development, grain filling capacity and grain quality of rice to elevated CO2 concentration, but the effects varied across different indices.

Tillering and small grain 1 dominates the tryptophan aminotransferase family required for local auxin biosynthesis in rice.

Auxin is a crucial phytohormone, controlling multiple aspects of plant growth and responses to the changing environment. However, the role of local auxin biosynthesis in specific developmental programs remains unknown in crops. This study characterized the rice tillering and small grain 1 (tsg1) mutant, which has more tillers but a smaller panicle and grain size resulting from a reduction in endogenous auxin. TSG1 encodes a tryptophan aminotransferase that is allelic to the FISH BONE (FIB) gene. The tsg1 mutant showed hypersensitivity to indole-3-acetic acid and the competitive inhibitor of aminotransferase, L-kynurenine. TSG1 knockout resulted in an increased tiller number but reduction in grain number and size, and decrease in height. Meanwhile, deletion of the TSG1 homologs OsTAR1, OsTARL1, and OsTARL2 caused no obvious changes, although the phenotype of the TSG1/OsTAR1 double mutant was intensified and infertile, suggesting gene redundancy in the rice tryptophan aminotransferase family. Interestingly, TSG1 and OsTAR1, but not OsTARL1 and OsTARL2, displayed marked aminotransferase activity. Meanwhile, subcellular localization was identified as the endoplasmic reticulum, while phylogenetic analysis revealed functional divergence of TSG1 and OsTAR1 from OsTARL1 and OsTARL2. These findings suggest that TSG1 dominates the tryptophan aminotransferase family, playing a prominent role in local auxin biosynthesis in rice.