Lower Tiller Research Articles

A maize semi-dwarf mutant reveals a GRAS transcription factor involved in brassinosteroid signaling.

Brassinosteroids (BR) and gibberellins (GA) regulate plant height and leaf angle in maize (Zea mays). Mutants with defects in BR or GA biosynthesis or signaling identify components of these pathways and enhance our knowledge about plant growth and development. In this study, we characterized three recessive mutant alleles of GRAS transcription factor 42 (gras42) in maize, a GRAS transcription factor gene orthologous to the DWARF AND LOW TILLERING (DLT) gene of rice (Oryza sativa). These maize mutants exhibited semi-dwarf stature, shorter and wider leaves, and more upright leaf angle. Transcriptome analysis revealed a role for GRAS42 as a determinant of BR signaling. Analysis of the expression consequences from loss of GRAS42 in the gras42-mu1021149 mutant indicated a weak loss of BR signaling in the mutant, consistent with its previously demonstrated role in BR signaling in rice. Loss of BR signaling was also evident by the enhancement of weak BR biosynthetic mutant alleles in double mutants of nana plant1-1 and gras42-mu1021149. The gras42-mu1021149 mutant had little effect on GA-regulated gene expression, suggesting that GRAS42 is not a regulator of core GA signaling genes in maize. Single-cell expression data identified gras42 expressed among cells in the G2/M phase of the cell cycle consistent with its previously demonstrated role in cell cycle gene expression in Arabidopsis (Arabidopsis thaliana). Cis-acting natural variation controlling GRAS42 transcript accumulation was identified by expression genome-wide association study (eGWAS) in maize. Our results demonstrate a conserved role for GRAS42/SCARECROW-LIKE 28 (SCL28)/DLT in BR signaling, clarify the role of this gene in GA signaling, and suggest mechanisms of tillering and leaf angle control by BR.

Partial replacement of a total mixed ration with annual ryegrass herbage: effects on dairy cow dry matter intake and milk production

ABSTRACT Studies with dairy cows receiving mixed ration and grazing annual pastures, which have low tiller density, are scarce. This study examined the effect of partial replacement of a total mixed ration (TMR) with annual temperate pasture. Treatments were ad libitum TMR (TMR100), 75% ad libitum TMR + ryegrass (Lolium multiflorum ‘Maximus’) (pTMR75), and 50% ad libitum TMR + ryegrass (pTMR50). Twelve multiparous Holstein and F1 Jersey × Holstein cows were divided into six groups (experimental units), taking account of milk production (26.6 ± 4.55 kg/day), days-in-milk (129 ± 50.8) and body weight (546 ± 30.6 kg). Treatments were compared using two 3 × 3 Latin square arangements, comprising three 21-day periods (measurements during final 5 days). Herbage DM intake increased from 4.8 kg/day with pTMR75 to 6.7 kg/day with pTMR50. Total DM intake decreased from 19.4 kg/day (TMR100), to 18.1 and 15.8 kg/day (pTMR75 and pTMR50, respectively). Milk production, energy corrected milk production (ECM), and milk fat content were similar between treatments, averaging 25.6, 28.4 kg/day and 44.6 g/kg, respectively. Ryegrass pastures were able to replace up to 50% of TMR offered to mid lactation dairy cows with no adverse effects on ECM production.

QTL Mapping of Tiller Number in Korean Japonica Rice Varieties.

Tiller number is an important trait associated with yield in rice. Tiller number in Korean japonica rice was analyzed under greenhouse conditions in 160 recombinant inbred lines (RILs) derived from a cross between the temperate japonica varieties Odae and Unbong40 to identify quantitative trait loci (QTLs). A genetic map comprising 239 kompetitive allele-specific PCR (KASP) and 57 cleaved amplified polymorphic sequence markers was constructed. qTN3, a major QTL for tiller number, was identified at 132.4 cm on chromosome 3. This QTL was also detected under field conditions in a backcross population; thus, qTN3 was stable across generations and environments. qTN3 co-located with QTLs associated with panicle number per plant and culm diameter, indicating it had pleiotropic effects. The qTN3 regions of Odae and Unbong40 differed in a known functional variant (4 bp TGTG insertion/deletion) in the 5' UTR of OsTB1, a gene underlying variation in tiller number and culm strength. Investigation of variation in genotype and tiller number revealed that varieties with the insertion genotype had lower tiller numbers than those with the reference genotype. A high-resolution melting marker was developed to enable efficient marker-assisted selection. The QTL qTN3 will therefore be useful in breeding programs developing japonica varieties with optimal tiller numbers for increased yield.

Tiller demography of tall fescue and tall wheatgrass cut at different times during the reproductive phase

AbstractBackgroundTall fescue (TF) and tall wheatgrass (TW) are the main temperate perennial grasses used for livestock grazing in the Pampas region of Argentina. In this region, pastures based on these grasses show low tiller density and the presence of bare soil in winter.MethodsAn experiment was performed in pots kept outdoors. Plants of TF and TW were cut every 550°C day and 700°C day, respectively. In each species, reproductive tillers were removed at different times: (i) at each cut, (ii) when they reached the flag leaf stage, or (iii) when they reached full bloom. Tiller appearance, tiller death, and type of bud (basal or axillary) of the tillers present were determined.ResultsTiller appearance decreased from July to April. Minimum values were 0.2 and 1.1 tillers 100 tillers−1 day−1 in TF and TW, respectively. In TF, tiller death began in September–October and increased from 0.2 to 0.8 tillers 100 tillers−1 day−1 in March–April. In TW, tiller death began in October–November and increased from 0.6 to 0.8–1.0 tillers 100 tillers−1 day−1 from February to April.ConclusionsDefoliation of reproductive tillers affected the tiller density of TF plants in spring and in the following fall. In TW, the treatments did not modify the tiller density of the plants.

Effects of Variety and Seeding Rate on Performance of Sweet Lupin (Lupinus angustifolius) at Holetta, in the Central Highlands of Ethiopia

The study was executed to evaluate the agro-morphological and nutritional performance of four narrow-leafed blue sweet lupin varieties (Australian lupin, Probor, Sanabor, and Vitabor) sown with five seeding rates (60, 70, 80, 90, and 100 kg/ha) during the main cropping seasons of 2014 and 2015 at Holetta in the central highlands of Ethiopia. Randomized complete block design replicated three times in factorial arrangements was used for experimenting. The lupin varieties were sown in rows with an inter-row spacing of 30 cm. At sowing, diammonium phosphate fertilizer at the rate of 100 kg/ha was uniformly applied for all treatments in both years. Data were collected on plant height, dry matter yield, number of pods per plant, number of seeds per pod, seed yield, and nutritive value. All measured data were subjected to analysis of variance using procedures of SAS general linear model. The result revealed that plant height, number of pods per plant, and number of seeds per pod of lupin varieties were significantly (P<0.001) affected by experimental years. The varietal difference was the major cause of variation (P<0.05) for dry matter yield, the number of pods per plant, and seed yield. The Sanabor, Probor and Vitabor varieties had 38, 23, and 20% dry matter yield advantage over the introduced Australian lupin variety, respectively. The Sanabor variety which produced the highest seed yield had 25, 17, and 14% seed yield advantages over Vitabor, Australian lupin, and Probor variety, respectively. The seed yield performance of lupin varieties was positively correlated with the number of pods per plant while it was negatively correlated with the number of seeds per pod. The dry matter yield and number of seeds per pod were also significantly (P<0.05) affected by seeding rates of lupin varieties. The dry matter yield of lupin varieties increased with increasing seeding rates indicating the tested lupin varieties had a low tillering performance. The number of seeds per pod of lupin varieties decreased with increasing seeding rates. On the other hand, the nutritive values did not differ significantly (P>0.05) among the tested lupin varieties. However, Vitabor variety gave better CP and IVDMD followed by Australian lupin while Probor variety gave the lowest CP and IVDMD. Vitabor variety which exhibited better ash, CP, and IVDMD contents produced the lowest NDF, ADF, and ADL contents when compared with other varieties. Generally, Sanabor and Probor varieties had better forage dry matter yield and seed yield but Vitabor and Australian lupin had relatively better nutritive values. For forage production, lupin varieties should be sown with the highest seeding rate (100 kg/ha) while the lowest seeding rate (60 kg/ha) is recommended for seed production. However, this research should be done across locations and over years to prove the above-recommended seeding rates for forage and seed productions in the study area and similar agro-ecologies. Keywords: dry matter yield, herbage quality, plant height, pod number, seed yield, seeding rate.

Transcriptional Expression of Nitrogen Metabolism Genes and Primary Metabolic Variations in Rice Affected by Different Water Status.

The era of climate change strongly requires higher efficiency of energies, such as light, water, nutrients, etc., during crop production. Rice is the world's greatest water-consuming plant, and, thus, water-saving practices such as alternative wetting and drying (AWD) are widely recommended worldwide. However the AWD still has concerns such as lower tillering, shallow rooting, and an unexpected water deficit. The AWD is a possibility to not only save water consumption but also utilize various nitrogen forms from the soil. The current study tried to investigate the transcriptional expression of genes in relation to the acquisition-transportation-assimilation process of nitrogen using qRT-PCR at the tillering and heading stages and to profile tissue-specific primary metabolites. We employed two water supply systems, continuous flooding (CF) and alternative wetting and drying (AWD), during rice growth (seeding to heading). The AWD system is effective at acquiring soil nitrate; however, nitrogen assimilation was predominant in the root during the shift from the vegetative to the reproductive stage. In addition, as a result of the greater amino acids in the shoot, the AWD was likely to rearrange amino acid pools to produce proteins in accordance with phase transition. Accordingly, it is suggested that the AWD 1) actively acquired nitrate from soil and 2) resulted in an abundance of amino acid pools, which are considered a rearrangement under limited N availability. Based on the current study, further steps are necessary to evaluate form-dependent N metabolism and root development under the AWD condition and a possible practice in the rice production system.

Morphological and metabolic differences between turfgrass and row‐crop biotypes of goosegrass (Eleusine indica)

AbstractThe research was conducted to evaluate Eleusine indica (L.) Gaertn. (goosegrass) phenotypic diversity in biotypes collected from managed turfgrass, noncrop, and row crop environments. A common‐garden experiment was conducted to quantify morphological characteristics. Biotypes were primarily distinguished along a single principal component that separated taller growing crop types with lower tiller numbers, larger leaves, and more spikelets per seedhead, contrasted with managed turfgrass and noncrop types with shorter height, greater tillering, fewer spikelets per seedhead but more total seedheads. A dwarf phenotype of E. indica (Texas‐GCPG) collected from a golf course putting green having shorter internodes, shorter leaves, and fewer spikelets per seedhead was distinct phenotypically compared with all other biotypes. Plant growth regulators were tested on biotypes collected from a cropping environment (PBU‐crop) and managed turfgrass (RB‐GC and Texas‐GCPG). Gibberellin inhibitors (paclobutrazol, flurprimidol, and trinexapac‐ethyl) had a negative impact on the growth of all three biotypes. Furthermore, the application of GA3 (gibberellin A3) increased Texas‐GCPG height compared with nontreated plants, suggesting it is a GA‐sensitive mutant. Molecular and biochemical research on such biotypes could shed light on pathways and mutations in any causal gene/s that prohibit or reduce active gibberellic acid production.

Discovery of aphid-transmitted Rice tiller inhibition virus from native plants through metagenomic sequencing.

A major threat to rice production is the disease epidemics caused by insect-borne viruses that emerge and re-emerge with undefined origins. It is well known that some human viruses have zoonotic origins from wild animals. However, it remains unknown whether native plants host uncharacterized endemic viruses with spillover potential to rice (Oryza sativa) as emerging pathogens. Here, we discovered rice tiller inhibition virus (RTIV), a novel RNA virus species, from colonies of Asian wild rice (O. rufipogon) in a genetic reserve by metagenomic sequencing. We identified the specific aphid vector that is able to transmit RTIV and found that RTIV would cause low-tillering disease in rice cultivar after transmission. We further demonstrated that an infectious molecular clone of RTIV initiated systemic infection and causes low-tillering disease in an elite rice variety after Agrobacterium-mediated inoculation or stable plant transformation, and RTIV can also be transmitted from transgenic rice plant through its aphid vector to cause disease. Finally, global transcriptome analysis indicated that RTIV may disturb defense and tillering pathway to cause low tillering disease in rice cultivar. Thus, our results show that new rice viral pathogens can emerge from native habitats, and RTIV, a rare aphid-transmitted rice viral pathogen from native wild rice, can threaten the production of rice cultivar after spillover.

IN SILICO AND GENETIC ANALYSIS RELATED TO TILLERING ABILITY IN MAIZE

Maize developed from its ancestor, teosinte, about 10,000 years ago. The evolution has gone from teosinte with multiple tillers to single-tiller maize plants. An investigation took place to identify and sequence genes related to tillering ability in maize and perform In silico analysis. Mating proceeded by manual pollination between the commercial hybrid SC2031 of maize (Zea mays L.) and the teosinte genotype Domiata (Durra rayyana). The parents, F1 hybrids, and their F2 progenies gained evaluation for tillering ability. The SC2031 (low or no-tillers) exhibited fragments ranging from 75 to 420 bp. The fragment observed with 262 bp size was in the F1 and nine out of 10 low-tillering F2 progenies. The Domiata parent, a high-tillering variety, exhibited three fragments ranging from 82 to 534 bp. The fragment with 445 in size occurred in nine out of 10 high-tillering F2 progenies. The fragment of 262 bp, which may be responsible for the low tillering ability, and the fragment of 445 bp, for the high tillering ability, were eluted from the gel, sequenced, and submitted to GenBank. The predicted protein, T1-L, of the DNA sequence from the low-tillering parent has a molecular weight of 6.69 kD and pI of 6.53, belonging to the GRAS family, which plays an important role as transcriptional factors required for the adequate pattern of radial rooting and shooting. The predicted protein, T1-H, of the DNA sequence from the high-tillering parent has a molecular weight of 14.08 kD, and pI of 7.97, belonging to the TEOSINTE BRANCHED 1, CYCLOIDEA, PCF1 (TCP) family that plays an essential role as transcriptional factors required for apical dominance.

Genetic Dissection of Tiller Number qTN4 in Rice

Tiller number (TN) is an important trait that contributes to yield in rice (Oryza sativa L.). A set of 76 chromosome segment substitution lines (CSSLs) derived from the super-hybrid cross between Zhonghui 9308 (ZH9308) and Xieqingzao B (XQZB) was used to map quantitative trait loci (QTL) controlling tiller number (TN). A total of four QTLs were detected in Fuyang, Zhejiang Province (30.15° N, 120° E). Two QTLs were detected in Lingshui, Hainan Province (18.5° N, 110° E) in our previous study. To further map the QTL on chromosome 4, namely qTN4, the line CSSL29 with a lower tiller number was selected to cross with ZH9308 to develop the secondary F2 population. In the F2:3 population, the qTN4 was validated and subsequently narrowed down to a 4.08 Mb region. What is more, combined phenotype with genotype, qTN4 was dissected into two QTLs, qTN4.1 and qTN4.2, in the F4:5 population. The qTN4.1 and qTN4.2 explained 34.31% and 32.05% of the phenotypic variance, with an additive effect of 1.47 and 1.38, respectively. Finally, the qTN4.1 and qTN4.2 were fine-mapped into a 193.55 Kb and 175.12 Kb intervals on chromosome 4, respectively. Based on genotype and phenotype, four near-isogenic lines (NILs) were selected in the mapping populations. Compared with NILCSSL29, tiller number (TN), grain setting rate, grain length (GL), the ratio of grain length to width (LWR) and grain yield per plant of NILZH9308, NIL-qTN4.1ZH9308 and NIL-qTN4.2ZH9308 were increased, and the heading date of these three lines were earlier than that of NILCSSL29. Interestingly, among the candidate genes of qTN4.1 and qTN4.2, except for LOC_Os04g23550, none of the other genes has been cloned, indicating the existence of a novel gene-controlling tiller number. These results lay a foundation for the analysis of QTL controlling tiller number in ZH9308 and provide a theoretical basis for the application of ZH9308 in super-hybrid breeding.

Parâmetros fisiológicos e produtivos de trigo afetados pela remoção de perfilhos e pela desfolha

Abstract The objective of this work was to evaluate the photosynthetic parameters, yield potential, and response to defoliation of wheat (Triticum aestivum) plants subjected to tiller removal. Two experiments were conducted under greenhouse conditions. In the first, the two following cultivars were evaluated for complete tiller removal: TBIO Audaz and BRS 394, with a high and low tillering capacity, respectively. In the second, only 'TBIO Audaz' was subjected to detillering and defoliation at post-anthesis. Tiller removal increased the yield potential of the main stem of both tested cultivars and the CO2 assimilation potential of the flag leaf, which was possibly a strategy to meet the demands for an increased sink strength, as evidenced by the response curves to irradiance and leaf internal CO2 concentration. The partial defoliation of 'TBIO Audaz' increased daily CO2 assimilation, both in intact and detillered plants. Detillered plants show a higher photosynthetic and yield potential of the main stem, but also a greater sensitivity to defoliation in the post-anthesis period.

Applicability of Water Saving Practices for Rice Cultivation in UAE with Simulated Alkaline Sandy Soil

The Korean government has performed the international cooperation project to develop rice cultivation methods under desert climate and alkaline sandy soils with the UAE government. Rice can be cultivated in alkaline sandy soil with paddy condition while it demands too much water. Four treatments were tested under protected plastic house: paddy cultivation with an impermeable layer (PP), furrow cultivation (F), furrow cultivation with an impermeable layer (FP), and furrow cultivation with clay dressing (FB). The impermeable layer prohibited percolation. Furrow cultivation reduced evaporation by irrigation only in the furrow. Clay dressing extend flooding periods to decline infiltration rates. Daily water consumption rates were 5.4 to 5.5 mm in furrow cultivation accounting for 57% of that in PP. The number of tiller was 16.0 in PP flooding all the time while they ranged from 4.4 to 6.8 in furrow cultivation treatments. The productivity in FP and FB were 84.1% and 78.9% out of that in PP. The water use efficiency in FP and FB, therefore, leached 1.4 to 1.5 times of that in PP. Based on the water use efficiency, FP and FB were proposed the applicable practices for reasonable productivity and water consumption. Furthermore, FP and FB have potential to raise productivity by increasing seeding rates considering low tillering rates.Changes in limited infiltration rate (Il) with clay contents: the soil consisted of synthesized very fine sand and bentonite as clay.

Characterization of anatomical features, developmental roadmaps, and key genes of bamboo leaf epidermis.

The exact developmental roadmaps of bamboo leaf epidermis and the regulating genes are largely unknown. In this study, we comprehensively investigated the morphological features of the leaf epidermis of bamboo, Pseudosasa japonica. We also established the developmental roadmaps of the abaxial epidermis along the linearly growing leaf. A variant of P. japonica, P. japonica var. tsutsumiana, with smaller stomata and higher stomata density, was identified. Further analysis revealed that the higher stomata density of the variant was due to the abnormal increase in stomata columns within the single stomata band. This abnormal development of stomata bands was observed as early as the guard mother cell stage in the leaf division zone (DZ). Interestingly, the developmental pattern of the single stomata was similar in P. japonica and the variant. Molecular data showed that PjDLT (Dwarf and Low Tillering) was significantly downregulated in leaves DZ of the variant. Overexpression of PjDLT in Arabidopsis and rice results in smaller plants with lower stomata density, whereas downregulation or mutation of OsDLT results in increased stomata density. Our results highlight the morphological features and developmental schedule of the leaf epidermis of bamboo and provide evidence that DLT plays an important role in regulating stomata in bamboo and rice.

Influence of subterraneous plant organs on yields and winter hardness of winter triticale (× Triticosecale Wittm.)

Purpose of this work was to identify the influence of the underground part of the plant on winter hardness and crop yields of collection of winter hexaploid triticale with different eco-geographical origin in the terms of Nonchernozem zone in Russia. The set of 43 hybrids of triticale with different eco-geographical origin was divided into 5 groups according to its origin: Dagestan, North Caucasus, Central Black Earth zone and Ukraine, Nonchernozem zone of Russia, Belarus and Eastern Europe. For every hybrid in a group, the number of plants with lower tillering node, availability and degree of epicotyl development and secondary root system calculated and the correlation analysis of these traits with grain yields performed. The grain yields considered as an integral indicator of the genotype adaptability for specific environment conditions. As a result, the triticale genotypes with stable development of a large number of plants with lower tillering node selected Mikola, Antey, Valentin, AD4, Timbo, AD 44 and Flamingo. The influence of environment conditions where the triticale hybrid created on selection of high yields genotype and increased number of plants with lower tillering node revealed. Greatest conjugacy between crop yields and availability of double tillering nodes is typical for hybrids from Central part of country and Belarus. It turned out that hybrids from southern regions have a positive relation of crop yields and the length of epicotyl. The hybrids from Central part of Russia, Belarus and Europe do not have this correlation. A weak positive relation in triticale hybrids found between development of secondary root system and grain yield.

Grain yield and kernel setting of multiple-shoot and/or multiple-ear maize hybrids

Rainfed maize ( Zea mays L.) crops in low-rainfall regions are cultivated at very low plant population densities that favor the production of fertile tillers or multiple ears in the main shoot. Little information exists regarding the functional processes governing grain yield and kernel setting on ears of different order of shoots of maize crops. To study these functional processes, field experiments were conducted cultivating two commercial maize hybrids (AX7784 and DM2738) under supplementary irrigation using different plant densities, N rates at sowing, shading around female flowering (silking) and tiller removal treatments. Hybrids differed in the number of tillers per plant at R 1 (AX7784 > DM2738). Early tiller removal increased main shoot growth rate around silking, suggesting competition for light among shoots. Kernel number per plant was positively and curvilinearly related with plant growth rate around silking, i.e. critical period (PGR CP ), in tillered and non-tillered plants of both hybrids. Tillered plants set higher kernel numbers than non-tillered plants at PGR CP > 9 g pl -1 d -1 (AX7784) or 11 g pl -1 d -1 (DM2738), while the opposite trend occurred at PGR CP values < 9 g pl -1 d -1 (both hybrids). In both hybrids, the combination of a higher biomass partitioning to but a lower reproductive efficiency of ears of tillers than of main shoots resulted in a lower kernel number for tillers than for main shoots. Genotypic differences were evident in kernel setting between main shoots (DM2738 > AX7784) and tillers (AX7784 > DM2738). The different pattern of kernel setting between hybrids was explained by differences in the biomass partitioning to tiller ears and the reproductive efficiency of ears of tillers (AX7784 > DM2738), and both the biomass partitioning to and the reproductive efficiency of second and third order ears of main shoots (DM2738 > AX7784). Kernel number per plant was higher for DM2738 due to a higher kernel setting on multiple ears of main shoot plus tillers (more prolific and with lower tiller fertility) than for AX7784 (less prolific and with higher tiller fertility). However, grain yield did not differ between hybrids, because of the higher kernel weight of AX7784. Therefore, this work opens avenues for exploiting higher grain yields in maize crops with low plant population densities through the combination of prolificacy and tillering. Further studies should analyze the impact of reproductive plasticity on kernel weight determination in low-density maize crops. • We studied maize tiller and main shoot grain yield and kernel set determinants. • Tillered plants set more kernels than non-tillered ones at high plant growth rates. • Tillers featured higher biomass partitioning to first order ears than main shoots. • Ears of tillers featured lower reproductive efficiency than ears of main shoots. • The tillering and prolific hybrid featured the highest plasticity, without grain yield differences between hybrids.

Nitrogen limits zinc‐mediated stimulation of tillering in rice by modifying phytohormone balance under low‐temperature stress

AbstractZinc (Zn) can improve resistance of rice plants to abiotic stress and promote the recovery of rice tillers by influencing auxin (IAA) synthesis, Zn absorption is closely related to nitrogen (N) concentrations; however, the mechanisms by which Zn regulates rice tiller recovery at low temperatures under different N levels are rarely studied. In this study, a solution culture experiment was conducted at two temperatures, three different Zn concentrations, and two N concentrations. Low temperature during the vegetative stage damaged the rice antioxidant system, suppressed nutrient uptake, and decreased the number of tillers. Increasing Zn application improved the resistance of rice plants to low‐temperature stress under normal N levels, enhanced nutrient absorption, improved tiller bud cytokinin (CTK) concentrations, and the CTK/IAA ratio, which accelerated tiller recovery relative to plants receiving standard Zn treatment. Shoot Zn concentrations were positively correlated with tiller numbers at normal N levels. High N attenuated the positive effect of Zn on rice tillering at low temperatures due to higher shoot Zn and IAA accumulation, and lower tiller buds CTK/IAA ratios. However, appropriate Zn application under high N levels was conducive to breaking tiller dormancy and promoting tillering growth spurts when recovering to normal temperature, which was related to the synergistic regulation of hormone balance and nutrient absorption by N and Zn. In conclusion, Zn could enhance rice low‐temperature stress resilience and facilitate tiller recovery via balancing the hormones in tiller buds. However, higher environmental N limited the stimulation of Zn on rice tillering under low temperature.

Intercropping red clover with intermediate wheatgrass suppresses weeds without reducing grain yield

AbstractIntermediate wheatgrass (IWG) [Thinopyrum intermedium (Host) Barkworth &amp; Dewey] is the first commercially produced perennial grain crop in the United States. Intercropping legumes with IWG has the potential to enhance dual‐purpose grain and forage production and contribute to weed control in organic management systems. We compared IWG with annual winter wheat (Triticum aestivum L.) in monoculture and intercropped with red clover (Trifolium pratense L.) in a 3‐yr experiment in central New York. Grain yield of IWG was lower than wheat in all years, partly due to lower tiller fertility and seed size in IWG. Compared with grain yield of 1,212 kg ha–1 in the first year, IWG grain yield was 83% (202 kg ha–1) and 64% lower (441 kg ha–1) in the second and third years, respectively. Intermediate wheatgrass straw production increased 40% from 5,541 to 7,785 kg ha–1 over 3 yr while wheat straw yield declined from 5,167 to 3,533 kg ha–1. Red clover did not affect grain or straw yield of either crop but reduced weed biomass and weed species richness. Weed communities in IWG plots were dominated by perennial grasses by the second year of production, whereas annual weeds were dominant in wheat throughout the experiment. Preventing establishment of perennial weeds that will persist in perennial grain cropping systems should be a management priority. High forage production observed when comparing IWG and wheat suggest opportunities for including IWG in integrated crop–livestock systems where IWG's higher forage yield and quality has higher utility.

Tillering dynamics in spring and summer of marandu palisade grass pastures previously used under deferred grazing

ABSTRACT This work was conducted to evaluate the effect of deferred pasture condition of Brachiaria brizantha cv. Marandu in the late winter on tillering during the growing season. The treatments were three pasture conditions at late winter: short pasture, tall pasture and tall/mown pasture. In September and October, tiller appearance rate (TApR) and tiller mortality rate (TMoR) were greater in the tall/mown pasture. In November and December, tall pasture presented greater TApR. From November to January the TMoR was greater in the tall pasture. The tiller stability index of short and tall/mown pastures were greater in October. The short pasture presented a greater tiller number than the tall and tall/mown pastures during the entire experimental period. Deferred and short pasture of marandu palisade grass at late winter presents in general lower tiller mortality and higher population density of tillers from the early spring onwards, in comparison to tall pasture. The mowing of marandu palisade grass with high forage mass at the late winter, although it only temporarily compromises the population stability of tillers, also stimulates its fast tillering from spring on.

Fine mapping of the tiller inhibition gene TIN4 contributing to ideal plant architecture in common wheat.

A tiller inhibition gene, TIN4, was mapped to an approximately 311kb genomic interval on chromosome arm 2DL of wheat. The tiller is one of the key components of plant morphological architecture and a central agronomic trait affecting spike number in wheat. Low tiller number has been proposed as a major component of crop ideotypes for high yield potential. In this study, we characterized the development of tillering in near-isogenic lines (NIL7A and NIL7B), indicating that the TIN4 gene inhibited the growth of tillering buds and negatively regulated tiller number. Low-tillering was controlled by a single gene (TIN4) located on chromosome 2DL by genetic analysis and bulked segregant RNA-seq analysis. A total of 17 new polymorphic markers were developed in this study, and 61 recombinants were identified in the secondary F2 population containing 4,266 individuals. TIN4 was finally mapped on a 0.35cM interval, co-segregated with molecular marker M380, within a 311kb genomic interval of the wheat cultivar Chinese Spring reference genome sequence that contained twelve predicted genes. Yield experiments showed that the yield of low-tillering lines was higher than that of high-tillering lines at a higher density. Overall, this study provides a foundation for the construction of a low-tillering ideotype for improving wheat yield and further cloning TIN4 by map-based cloning approach.

OsARP6 Is Involved in Internode Elongation by Regulating Cell-Cycle-Related Genes.

The SWR1 complex (SWR1-C) is important for the deposition of histone variant H2A.Z into chromatin to regulate gene expression. Characterization of SWR1-C subunits in Arabidopsis thaliana has revealed their role in variety of developmental processes. Oryza sativa actin related protein 6 (OsARP6) is a subunit of rice SWR1-C. Its role in rice plant development is unknown. Here, we examined the subcellular localization, expression patterns, and loss of function phenotypes for this protein and found that OsARP6 is a nuclear localized protein, and is broadly expressed. OsARP6 interacted with OsPIE1, a central ATPase subunit of rice SWR1-C. The osarp6 knockout mutants displayed pleiotropic phenotypic alterations in vegetative and reproductive traits, including semi-dwarf phenotype, lower tillers number, short leaf length, changes in spikelet morphology, and seed abortion. Microscopic thin sectioning of the top internode revealed that the dwarf phenotype of osarp6 was due to reduced number of cells rather than reduced cell length. The altered transcript level of genes involved in cell division suggested that OsARP6 affects cell cycle regulation. In addition, H2A.Z levels were reduced at the promoters and transcription start sites (TSS) of the regulated genes in osarp6 plants. Together, these results suggest that OsARP6 is involved in rice plant development, and H2A.Z deposition.