OsNPF3.1,a nitrate,abscisic acid and gibberellin transporter gene,is essential for rice tillering and nitrogen utilization efficiency

Low-affinity nitrate transporter genes have been identified in subfamilies 4-8 of the rice nitrate transporter 1(NRT1)/peptide transporter family(NPF),but the OsNPF3 subfamily responsible for nitrate and phytohormone transport and rice growth and development remains unknown.In this study,we described OsNPF3.1 as an essential nitrate and phytohormone transporter gene for rice tillering and nitrogen utilization efficiency(NUtE).OsNPF3.1 possesses four major haplotypes of its promoter sequence in 517 cultivars,and its expression is positively associated with tiller number.Its expression was higher in the basal part,culm,and leaf blade than in other parts of the plant,and was strongly induced by nitrate,abscisic acid(ABA)and gibberellin 3(GA_3)in the root and shoot of rice.Electrophysiological experiments demonstrated that OsNPF3.1 is a pH-dependent low-affinity nitrate transporter,with rice protoplast uptake assays showing it to be an ABA and GA_3 transporter.OsNPF3.1 overexpression significantly promoted ABA accumulation in the roots and GA accumulation in the basal part of the plant which inhibited axillary bud outgrowth and rice tillering,especially at high nitrate concentrations.The NUtE of OsNPF3.1-overexpressing plants was enhanced under low and medium nitrate concentrations,whereas the NUtE of OsNPF3.1 clustered regularly interspaced short palindromic repeats(CRISPR)plants was increased under high nitrate concentrations.The results indicate that OsNPF3.1 transports nitrate and phytohormones in different rice tissues under different nitrate concentrations.The altered OsNPF3.1 expression improves NUtE in the OsNPF3.1-overexpressing and CRISPR lines at low and high nitrate concentrations,respectively.

Two splicing variants of amino acid transporter-like 4(OsATL4)negatively regulate rice tillering and yield by mediating the transport of amino acids

Amino acids are the primary form of nitrogen utilization in higher plants,mainly transported by amino acid transporters.In this study,we analyzed the natural variation of amino acid transporter-like 4(OsATL4)in rice germplasm resources,identified its spatiotemporal expression characteristics,determined its substrate transport,and validated its function using transgenic plants.We found that the promoter sequence of OsATL4 varied across 498 rice varieties.The expression level of OsATL4 was higher in japonica rice,which was negatively correlated with tiller number and grain yield.OsATL4 was highly expressed in the basal part,leaf sheath,stem,and young panicle,with its two splicing variants localized to the cell membrane.OsATL4a(the long splicing variant)had a high affinity for transporting Ser,Leu,Phe,and Thr,while OsATL4b(the short splicing variant)had a high affinity for transporting Ser,Leu,and Phe.Blocking OsATL4 promoted axillary bud outgrowth,rice tillering,and grain yield,whereas overexpression lines exhibited the opposite phenotype.Exogenous application of low concentrations of Ser promoted axillary bud outgrowth in overexpression lines,while high concentrations of Ser inhibited it.Conversely,the mutant lines showed the opposite response.Altered expression of OsATL4 might affect the expression of genes in nitrogen,auxin,and cytokinin pathways.We propose that two splicing variants of OsATL4 negatively regulate rice tillering and yield by mediating the transport of amino acids,making it a significant target for high-yield rice breeding.

The auxin transporter OsAUX1 regulates tillering in rice(Oryza sativa)

Tillering is an important agronomic trait of rice(Oryza sativa)that affects the number of effective panicles,thereby affecting yields.The phytohormone auxin plays a key role in tillering.Here we identified the high tillering and semi-dwarf 1(htsd1)mutant with auxin-deficiency root characteristics,such as shortened lateral roots,reduced lateral root density,and enlarged root angles.htsd1 showed reduced sensitivity to auxin,but the external application of indole-3-acetic acid(IAA)inhibited its tillering.We identified the mutated gene in htsd1 as AUXIN1(OsAUX1,LOC_Os01g63770),which encodes an auxin influx transporter.The promoter sequence of OsAUX1 contains many SQUAMOSA PROMOTER BINDING PROTEIN-LIKE(SPL)binding sites,and we demonstrated that SPL7 binds to the OsAUX1 promoter.TEOSINTE BRANCHED1(OsTB1),a key gene that negatively regulates tillering,was significantly downregulated in htsd1.Tillering was enhanced in the OsTB1 knockout mutant,and the external application of IAA inhibited tiller elongation in this mutant.Overexpressing OsTB1 restored the multi-tiller phenotype of htsd1.These results suggest that SPL7 directly binds to the OsAUX1 promoter and regulates tillering in rice by altering OsTB1 expression to modulate auxin signaling.

The dual role of casein kinase 1,DTG1,in regulating tillering and grain size in rice

Tiller number and grain size are important agronomic traits that determine grain yield in rice.Here,we demonstrate that DEFECTIVE TILLER GROWTH 1(DTG1),a member of the casein kinase 1 protein family,exerts a co-regulatory effect on tiller number and grain size.We identified a single amino acid substitution in DTG1(I357K)that caused a decrease in tiller number and an increase in grain size in NIL-dtg1.Genetic analyses revealed that DTG1 plays a pivotal role in regulation of tillering and grain size.The DTG1^(I357K) allelic variant exhibited robust functionality in suppressing tillering.We show that DTG1 is preferentially expressed in tiller buds and young panicles,and negatively regulates grain size by restricting cell proliferation in spikelet hulls.We further confirm that DTG1 functioned in grain size regulation by directly interacting with Grain Width 2(GW2),a critical grain size regulator in rice.The CRISPR/Cas9-mediated elimination of DTG1 significantly enhanced tiller number and grain size,thereby increasing rice grain yield under field conditions,thus highlighting potential value of DTG1 in rice breeding.

Effects of Different Application Times of Tillering Fertilizer on Grain Yield and Population Development of Double-cropping Rice Transplanted by Machine

The application of tillering fertilizer plays an important role in promoting rice tillering and improving rice yield. However, under the condition of mechanical transplanting, the optimal application time of tillering fertilizer is still unclear. In this study, the early rice cultivar Zhongjiazao 17 and late rice cultivar H You 518 were used as materials, and the effects of different application times of tillering fertilizer on yield and population development of double-cropping rice transplanted by machine were investigated. The tillering fertilizer was applied 7（D07）, 10（D10） and 13（D13） d after the transplanting, respectively. The results showed that compared with those in the D07 treatment groups, the yield of early rice in the D10 and D13 treatment groups were reduced by 9.4% and 3.8%, respectively, and the yield of late rice in the D10 and D13 treatment groups were reduced by 4.5% and 12.6%,respectively. However, there were no significant differences in rice yield among the treatment groups. The application time of tillering fertilizer showed significant effects on grain number per panicle and seed setting rate of early rice. The grain number per panicle in the D10 treatment group was significantly lower than that in the D07 treatment group, and the seed setting rate of the D13 treatment group was significantly lower than that in the D07 treatment group（P〈0.05）. For the late rice, the effect of application time of tillering fertilizer on effective tiller number was most obvious, and the effective tiller number in the D13 treatment group was significantly lower than that in the D07 treatment group（P〈0.05）. Compared with those in the D07 treatment group, the effective tiller numbers, leaf area indexes and biomasses in the D10 and D13 treatment groups were all trended to be decreased. Therefore,to improve the quality of population and fulfill the high-yielding potential of double-cropping rice transplanted by machine, the tillering fertilizer should be applied as early as possible after rice seedlings turn green.

Tillering Characteristics of Different Varieties of Double-season Rice under Different Mechanical Transplanting Modes

A total of 8 early-season and late-season rice varieties with different growth periods were selected, and their tillering characteristics under wide-narrow row and equal row .transplanting modes were studied. The results showed that the length of slow growth phase was related to the performance of transplanter; the ef- fect of mechanical transplanting on tillering of early-season rice was greater than that of late-season rice; Compared with late-season rice, early-season rice showed later tillering and longer tillering period; the tiller number per plant and effective panicle number per plant differed greatly among different varieties of double-season rice; under the condition of same transplanting density, the tillers of rice under wide- narrow row transplanting mode appeared rapidly and disappeared slowly, and wide- narrow row transplanting mode improved tillering, effective panicle number and yield of rice; different varieties of double-season rice showed different adaptability to me- chanical transplanting, and the varieties with short growth period, strong tilledng a- bility and more effective panicles per plant were more suitable for mechanical trans- planting; the effect of mechanical transplanting on rejuvenation of rice could be im- proved by improving the performance of transplanter.

Yield and tillering response of super hybrid rice Liangyoupeijiu to tillage and establishment methods

Tillering is an important agronomic trait for rice grain production. To evaluate yield and tillering response, Liangyoupeijiu(super hybrid rice) was grown in Hunan, China during 2011–2012 under different methods of tillage(conventional and no-tillage system) and crop establishment methods(transplanting at a spacing of 20 cm × 20 cm with one seedling per hill and direct seeding at a seeding rate of 22.5 kg ha-1). Our results revealed that, at maximum tillering(Max.) and at maturity(MA) stages, direct seeding(DS) resulted in 22% more tillers than transplanting(TP) irrespective of tillage system. Tiller mortality reached a peak between panicle initiation(PI) and booting(BT) stages, and was 16% higher under conventional tillage(CT) than under no-tillage(NT). Transplanting required 29% more time for the completion of tillering and less for DS. Tillering rate was 43% higher in DS than TP under either CT or NT. There was a positive correlation between panicle number per m2and maximum tiller number per m2, but not panicle-bearing tiller rate. The panicle bearing tiller rate was higher under DS than TP and higher under NT than CT. Tiller dry weight gradually increased up to heading(HD) stage, and was 14% higher under TP than DS. Leaf area(cm2tiller-1) gradually increased from Max. to HD stage and then decreased by 34% in conventional tillage transplanting(CTTP) and 45% in no-tillage transplanting(NTTP) from 12DAH–24DAH(days after heading), but was similar(35%) under DS under either CT or NT. Grain yield was higher under CTTP owing to the larger sink size(heavier panicle, more spikelets in per cm length of panicle) than under DS.

Genetic, hormonal, and environmental control of tillering in wheat

Tillering contributes greatly to grain yield in wheat.Investigating the mechanisms of tillering provides a theoretical foundation and genetic resources for the molecular breeding of wheat.The regulation of tillering is a complex molecular process that involves a multitude of factors.Little is known about the molecular mechanisms in the wheat genome,although progress has been made in rice.Here we review the developmental characteristics of tillers and summarize current knowledge of the roles of endogenous and environmental factors in wheat tillering.We propose directions for future studies and advanced technologies to be used for gene identification and functional studies.

Straw mulch-based no-tillage improves tillering capability of dryland wheat by reducing asymmetric competition between main stem and tillers

The moisture-conserving effect of straw mulch-based no-tillage(SMNT)is expected to increase fertile spikes and grain yield in environments with rainfall less than 200 mm.However,the mechanisms under-lying the positive effect of SMNT on wheat tillering are not fully elucidated.A split-plot experiment was designed to investigate the combined effects of SMNT and cultivars on tillering of dryland wheat grown under both dry and favorable climates.Application of SMNT to a cultivar with 1-2 tillers exploited both tillering and kernel-number plasticity,increasing the mean grain yield by 20.5%.This increase was attrib-uted primarily to an increased first-tiller emergence rate resulting from increased N uptake,leaf N con-tent,and N remobilization from tillers to their grain.The second and third tillers,as transient sinks,contributed to the tiller survival rate,which depends on tiller leaf number.The increased total N uptake by SMNT also increased the dry mass yield of tillers and the C:N ratio,reducing the asymmetric compe-tition between main stem and tillers.Owing to these beneficial effects,reduced mitogen-activated pro-tein kinase(MAPK)and abscisic acid signals were observed under SMNT,whereas indole-3-acetic acid(IAA)signals and genes involved in DNA replication and mismatch repair were increased.These signals activated three critical transcription factors(the calmodulin-binding transcription activator,GRAS domain,and cysteine-2/histidine-2 family)and further increased rapid drought response and tiller main-tenance after stem extension.Phenylpropanoid biosynthesis,sphingolipid biosynthesis,and galactose metabolism were most relevant to increased tillering under SMNT because of their critical role in drought response and lignin biosynthesis.Our results suggest that straw mulch-based no-tillage activates rapid drought response and improved wheat tillering by coordinating root N uptake,N remobilization,and asymmetric competition between main stem and tillers.

Effects of key growth conditions on endogenous hormone content in tillering stem bases,germination of lateral buds,and biomass allocation in Indocalamus decorus

Physiological responses and changes in growth of Indocalamus decorus Q.H.Dai under different ecological conditions are essential for further understanding growth regulation and adaptive mechanisms and establishing an evidence-based management system for optimal growth. In this study, the endogenous hormone content in tillering stem bases, germination of lateral buds, and biomass allocation of this bamboo species in different growth environments were investigated. Among the endogenous hormones in the basal stems of tillers, indole-3-pyruvic acid and zeatin riboside were highly correlated with lateral buds that germinated to form shoots, while gibberellic acid was highly correlated with lateral buds that germinated to form rhizomes. The best lateral bud germination characteristics were achieved with full sun, a density of six plantlets per pot, and watering every 6 days. I. decorus plantlets used different resource allocation strategies depending on treatment. Different ecological factors influenced endogenous hormones in the bamboo stem base,which affected lateral bud germination and biomass allocation.

Research Progress of Regulatory Factors for Tillering and Earring of Large-spike and Multispike Cultivars of Winter Wheat

To research the regulation factors and regulating mechanism for tillering and earring of large-spike and multi-spike cultivars of winter wheat,and achieve yield improvement,this article summarized the research progress of the influence of genetic factors,group environment factors and endogenous hormones on tillering and earring of different spike cultivars of winter wheat,and pointed out that the future research should focus on the relationship between various factors and influencing mechanism of regulation factors of different tillers.According to studying the relationship among content of hormone,hormones balance,gene expression and regulation,and wheat tillering,this article will provide theoretical basis and technical support for high-yield cultivation of winter wheat.

Identification and Cloning of Tillering-Related Genes OsMAX1 in Rice

Tillering is an important agronomic trait which has a direct impact on plant type and grain yield. Strigolactones are a class of important phytohormones regulating rice tillering. ATMAX1 is an important gene involved in strigolactone biosynthesis through encoding the protein P450 in Arabidopsis. Based on sequence BLASTp, we identified five homologous genes of ATMAX1 in rice, i.e., OsMAXla, OsMAXlb, OsMAXlc, OsMAXld and OsMAXle. Among them, OsMAXla and OsMAXle showed stable and high expression in rice tissues. In addition, we observed that OsMAXla and OsMAXle can rescue the branched phenotype and the influences caused by MAX1 mutation in Arabidopsis. Moreover, the expression of OsMAX1a and OsMAXle can respond to phosphate deficiency and different phytohormones, especially GR24, a strigolactone analogue. Therefore, it is concluded that OsMAX1a and OsMAX1e are involved in the biosynthesis of strigolactones and regulated rice tillering.

Advances in studies on the physiological and molecular regulation of barley tillering

Tillering is a crucial trait closely associated with yield potential and environmental adaptation in cereal crops,regulated by the synergy of endogenous(genetic)and exogenous(environmental)factors.The physiological and molecular regulation of tillering has been intensively studied in rice and wheat.However,tillering research on barley is scarce.This review used the recent advances in bioinformatics to map all known and potential barley tiller development genes with their chromosomal genetic and physical positions.Many of them were mapped for the first time.We also discussed tillering regulation at genetic,physiological,and environmental levels.Moreover,we established a novel link between the genetic control of phytohormones and sugars with tillering.We provided evidence of how environmental cues and cropping systems help optimize the tiller number.This comprehensive review enhances the understanding of barley’s physiological and genetic mechanisms controlling tillering and other developmental traits.

Effects of Seed Soaking with Paclobutrazol on Tillering and Physio-logical Characteristics of Sugarcane Seedlings

In order to study the effects of seed soaking with Paclobutrazol( PP333) on the tillering and physiological characteristics of sugarcane seedlings,sugar cane variety ROC22 was used as experimental material. The effects of seed soaking with different concentrations of PP333 were studied. The tiller number and growth of sugarcane were surveyed at the 6-leaf stage,the physiological indicators such as chlorophyll content,soluble protein content,proline content and peroxidase activity were measured at the 2-leaf,4-leaf,and 6-leaf stages. The results showed that the seed soaking with PP333 can effectively improve the tillering of sugarcane seedlings. The suitable concentration for the tillering of sugarcane and the growth and development of sugarcane was of 50 mg/L; the seed soaking with PP333 significantly increased the chlorophyll,soluble protein,proline,and peroxidase activity of leaves of sugarcane seedlings; the content of chlorophyll and soluble protein in leaves of sugarcane seedlings treated with 90 mg/L PP333 was the highest,and the proline content and peroxidase activity of sugarcane treated with 50 mg/L PP333 were the highest.

Studies on the Morphological Characters of South China Double Cropping Super Rice at the Active Tillering Stage

The morphological characters of the newly released super hybrid rice in South China, Yueza 122, Fengyou 428, Peiza 67, and super conventional varieties, Guangchao 3, Shengtai 1 at the active tillering stage in both early and late crops were investigated. Using the analysis of variance and other statistic methods, the ideal morphological characteristics of South China double cropping super-rice at the active tillering stage were determined. They are 55-60 cm in the early crop and 60-76 cm in the late crop for the ideal plant height, about 15 tillers in the early crop and 14-19 tillers in the late crop for the ideal tiller number per plant, 40-44 cm in the early crop and 42-60 cm in the late crop for the ideal length of the first leaf under the top leaf, 1.2-1.4 cm in the early crop and 1.2-1.3cm in the late crop for the ideal width of the first leaf under the top leaf, 39- 44 cm in the early crop and 37-43 cm in the late crop for the ideal length of the second leaf under the top leaf, 1.1-1.4 cm in the early crop and about 1.1 cm in the late crop for the ideal width of the second leaf under the top leaf, 22-58o in the early crop and 4- 12o in the late crop for the ideal top leaf angle at the active tillering stage. Based on these results, a new concept of “dynamic plant type structure” for South China double cropping super rice breeding was suggested.

Effects of Seed Soaking with Paclobutrazol on Early Tillering and Endogenous Hormone Contents of Sugarcane Seedlings

[ Objective] The paper was to explore the effect of seed soaking with paclobutrazol （ PP333 ） on early tillering and endogenous hormone content of sugarcane seedlings. [ Method ] With the sugarcane variety ROC22 as the experimental material, seeds were soaked in different concentrations of PP333- The number and growth of tiller were investigated, and the contents of endogenous hormones IAA, CTK, ABA and GA3 at two-leaf, four-loaf and six-leaf stages of sugarcane seedlings were measured, to study the effects of seed soaking with PP333 on early filleting and endogenous hormone contents of sugarcane seedlings. [Result] Seed soaking with PP333 could effectively improve and advance filleting occurrence of sugarcane seedlings. The suitable PP333 concentration for sugarcane fiUeting occurrence, growth and development was 50 mg/L. Seed soaking with PP333 significantly increased the CTK and ABA contents in leaves of sugarcane seedlings, and decreased IAA and GA3 contents. [ Conclusion]The paper will provide a theoretical basis for application of PP333 in sugarcane production.

A Standardized Method for Determining Tillering Capacity of Wheat Cultivars

Genotype and agronomic management greatly influence crop growth and grain yield in wheat (Triticum aestivum L.). To ensure sustainable production, seeding rate selection is important to maximize efficiency of every plant. Tillering can allow wheat plants to adjust growth relative to plant density and quality of growing conditions. This research sought to determine a method for assessing tillering of wheat cultivars and develop a standardized approach for characterizing cultivar tillering capacity. Nine cultivars with diverse genetic and phenotypic characteristics were seeded in 2017-2018 at Prosper, ND using various seeding techniques at differing plant spacing arrangements to evaluate tillering habit and spikes plant-1. Cultivars grown at population densities common in grower fields did not express full tillering potential. Spaced-plantings of cultivars promoted cultivar expression of tillering phenotype. The SOFATT (seed only a few, and then thin) method, where average spikes plant-1 was determined from multiple plants sampled from a cultivar grown at spaced-plantings (inter-row and intra-row spacing at 30 ± 12 cm), is recommended to properly assess tillering habits of wheat cultivars. Breeders and researchers can use results from SOFATT evaluations to determine tillering capacity rating for each cultivar based on raw or transformed z-score values for spikes plant-1.

Identification and Genetic Characterization of a Novel Tillering Dwarf Semi-Sterile Mutant <i>tdr</i>1 in Rice

Tillering and plant height are important components of plant architecture and grain production in rice. We identified a novel high tillering, dwarf and semi-sterile mutant, as named tdr1 in a rice maintainer line E20 derived from the cross between between IR68888B and Luxiang 90. The investigation of tiller dynamic in the tdr1 line displayed 3 different phases: rapid increasing of tillers in the vegetative growth stage, producing no new tillers in the transition stage from the vegetative growth to reproductive growth, and regeneration of new tillers after heading. The assay of hormones showed the significant reduction of brassinolide level and no change of the levels of gibberellic acid, cytokinin and strigolactone in the tdr1 line. Genetic analysis indicated the phenotype of high tillering, dwarfism and semi-sterility is controlled by a recessive gene in several different segregation populations. The TDR1 gene was mapped in the 105 kb interval between RM3288 and RM6590 on chromosome 4. Cloning of TDR1 gene would provide a new opportunity to uncover the molecular mechanism of the development of plant height and tiller in rice.

Creation of Cultivars with High Productive Tillering Capacity and Synchronous Earing for Ridge Technology Cultivation

For cultivation of new common wheat cultivars having valuable morphological traits new resource-saving ridge technology was applied. Our collection of dwarf lines, obtained in the result of cyclical diallel crossings of genotrophs, induced by pyridine carbonic acids, zoned common wheat cultivars and short stem common wheat samples from the World Wide Collection of the Russian Institute of Plant Industry, was applied for creation of new common wheat lines having valuable morphological traits. It was observed that open blooming dwarfs were good for cross-pollination, and without insulation they demonstrated a great issue of natural hybrids. It was marked that cross-pollination promoted appearance of great number of hybrid plants with high productive tillering capacity. After individual selection among those hybrid plants and their propagation we got fertile constant lines of common winter wheat having 17-20 productive stems per one plant and a productive ear. These lines are firm and resistant to lodging. At the present time these constant lines are cultivated in conditions of resource-saving ridge technology.

Effects of leaf N concentration and leaf area index on determining rice tillering

Relative tillering rate(RTR)increased linear-ly with the increasing of leaf N concentration(NLV)has been already reported.To testwhether this relationship could be used toquantitatively explain the difference in tilleringamong a wide range of N application,field ex- periments were conducted at the IRRI farm,Los Banos,Laguna,the Philippines.Two in- dica cultivars,IR 72 and IR68284H wereused.For each cultivar,12 treatments includ- ing 4 N levels(0,60,120,and 180kgN·ha)and 3 transplanting spacing(30×20,20×20,and 10×20cm)were arranged in a ran-domized split-plot design with 4 replications.The N treatments were designated as mainplots and spacings as subplots.Fourteen-day-old seedlings were transplanted with 3seedlings per hill.The subplot area was 20m~2.Nitrogen fertilizer was applied as basal,atmidtillering,and at panicle initiation in threeequal splits.P,K,and Zn were applied asbasal at normal dosage.The field was flooded.Plant samples were taken every 7-14 d from 14d after transplanting to flower