Decrease In Tiller Number Research Articles

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 DTG1I357K 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.

Assessment of Physiological, Biochemical and Yield Attributes of Rice Cultivars under Elevated Ozone Stress

The present study aimed to assess the response of 15 rice cultivars exposed to elevated ozone stress. The plants were exposed to 100 ppb ozone (10:00– 17:00 h) for 30 days at the reproductive stage. Elevated ozone significantly alters the physiological, biochemical, growth and yield traits of all test rice cultivars. Elevated ozone exposure significantly decreased photosynthetic rate maximally in MDU5 (42.90%) and TRY(R)2 showed maximum reduction in stomatal conductance (42.39%) and chlorophyll content (41.22%). In terms of yield traits, a decrease in tiller number, number of effective tillers, number of filled spikelets per panicle and 1000 grain weight over the control were also observed. The multivariate analysis with a total variance of 58.86% categorized the 15 rice cultivars into ozone sensitive (TRY(R) 2, ASD16, ADT(R)45 and MDU5), moderately ozone sensitive (ASD18, ADT43, Rice MDU6, ADT36 and ADT37), moderately ozone tolerant (ADT(R)48 CO47 and Rice CO51) and ozone tolerant (Rice TPS5, Anna(R)4 and PMK(R)3) under 100 ppb ozone. The present results revealed that the ozone tolerant rice cultivars would be recommended to cultivate in the regions experiencing high ozone concentration.

SLR1 inhibits MOC1 degradation to coordinate tiller number and plant height in rice

The breeding of cereals with altered gibberellin (GA) signaling propelled the ‘Green Revolution’ by generating semidwarf plants with increased tiller number. The mechanism by which GAs promote shoot height has been studied extensively, but it is not known what causes the inverse relationship between plant height and tiller number. Here we show that rice tiller number regulator MONOCULM 1 (MOC1) is protected from degradation by binding to the DELLA protein SLENDER RICE 1 (SLR1). GAs trigger the degradation of SLR1, leading to stem elongation and also to the degradation of MOC1, and hence a decrease in tiller number. This discovery provides a molecular explanation for the coordinated control of plant height and tiller number in rice by GAs, SLR1 and MOC1.

Transferring a Biomass Enhancement Biotechnology from Glasshouse to Field: A Case Study on Wheat GWD RNAi

In glasshouse studies we have previously shown that endosperm-specific RNAi suppression of the primary starch phosphorylation enzyme, Glucan, Water Dikinase (GWD) leads to enhanced early vigor, greater leaf biomass, and increases in both head size and yield. To confirm these affects in a field setting, trials were conducted in three Australian environments. Field results were consistent with those in the glasshouse for increased flag leaf area and rachis nodes. However, there was also a decrease in tiller number and consequently a decrease in yield for one event at two sites. These findings provide potentially important information on plant vigor enhancement and highlight the challenges of transferring the modification of complex traits from single plants in controlled environments to the field.

Correlation analysis of growth, yield and yield components of wheat (Triticum aestivum) under varying weed densities

A study was carried out at Student's Farm, Department of Agronomy, Punjab Agricultural University, Ludhiana during rabi 2010-11 and 2011-12. The experimental site was sandy loam, with normal soil pH and electrical conductivity, low in organic carbon and available N and medium in available P and K. The investigation consisted of 11 treatments each having different population levels of button weed (Malva neglecta) and kandyali palak (Rumex spinosus), viz 0,3,6,9,12 plants/m2 and two treatments having pure populations of each weed. Wheat crop accumulated more heat units (AGDD, AHTU, APTU) during the year 2011-12 as compared to the crop year 2010-11. Increase in population levels of both weed species significantly decreased the crop growth rate (CGR) and relative growth rate (RGR) of wheat crop. The results showed a significant decrease in number of tillers, effective tillers, number of grains/ear, 1 000-grain weight and grain yield of wheat with increasing population densities of Malva neglecta and Rumex spinosus (from 3 to 12 plants/m2). Highest grain yield of wheat (57.54 q/ha) was recorded under pure wheat treatment and lowest grain yield was recorded in treatments T5 and T10 having 12 plants of Malva neglecta and Rumex spinosus, respectively. Highest heat use efficiency (HUE) was recorded in pure wheat treatment in contrast to all other treatments. Determination of correlation matrix revealed that crop yield was perfectly negatively correlated with population densities of Malva neglecta and Rumex spinosus while there was highly significant direct relationship with other crop growth parameters like dry matter accumulation, LAI, tiller number/m2, effective tillers/m2, ear length, and number of grains/ear etc. Regression analysis interpreted positive relation of grain yield with growth parameters and negative with both weed population densities. From the study it was concluded that higher weed infestation enhances inhibitory influence on the growth rate, heat use efficiency and yield of wheat crop.

Isolation of a Novel Lodging Resistance QTL Gene Involved in Strigolactone Signaling and Its Pyramiding with a QTL Gene Involved in Another Mechanism

Lodging has been a major roadblock to attaining increased crop productivity. In an attempt to understand the mechanism for culm strength in rice, we isolated an effective quantitative trait locus (QTL), STRONG CULM3 (SCM3), the causal gene of which is identical to rice TEOSINTE BRANCHED1 (OsTB1), a gene previously reported to positively control strigolactone (SL) signaling. A near-isogenic line (NIL) carrying SCM3 showed enhanced culm strength and increased spikelet number despite the expected decrease in tiller number, indicating that SL also has a positive role in enhancing culm strength and spikelet number. We produced a pyramiding line carrying SCM3 and SCM2, another QTL encoding APO1 involved in panicle development. The NIL-SCM2+SCM3 showed a much stronger culm than NIL-SCM2 and NIL-SCM3 and an increased spikelet number caused by the additive effect of these QTLs. We discuss the importance of utilizing suitable alleles of these STRONG CULM QTLs without inducing detrimental traits for breeding.

Isolation of a novel lodging resistance QTL gene involved in strigolactone signaling and its pyramiding with a QTL gene involved in another mechanism.

Lodging has been a major roadblock to attaining increased crop productivity. In an attempt to understand the mechanism for culm strength in rice, we isolated an effective quantitative trait loci (QTL), STRONG CULM3 (SCM3), the causal gene of which is identical to rice TEOSINTE BRANCHED1 (OsTB1), a gene previously reported to positively control strigolactone (SL) signaling. A near-isogenic line (NIL) carrying SCM3 showed enhanced culm strength and increased spikelet number despite the expected decrease in tiller number, indicating that SL also has a positive role in enhancing culm strength and spikelet number. We produced a pyramiding line carrying SCM3 and SCM2, another QTL encoding APO1 involved in panicle development. The NIL-SCM2+SCM3 showed a much stronger culm than NIL-SCM2 and NIL-SCM3 and an increased spikelet number caused by the additive effect of these QTLs. We discuss the importance of utilizing suitable alleles of these STRONG CULM QTLs without inducing detrimental traits for breeding.

Dynamics of structural traits in two competing C3grass species: influence of neighbours and nitrogen

AbstractThis work analysed the regulatory structural mechanisms involved in the competitive interactions between the annual grassBromus willdenowiiKunth. (BW = prairie grass) and the perennial C3grassDactylis glomerataL. (DG= orchardgrass) during pasture establishment. Four combinations of species (pureBW, pureDG,DGflanked byBWandBWflanked byDGplants), with and without winter nitrogen fertilization, were factorially arranged in a randomized complete block design. Data were recorded at two organization levels: tillers (three tiller age cohorts) and target plants. Annual neighbours caused a decrease in the number of living leaves in tillers of intermediate age of both species. This structural regulatory mechanism led to a decrease in tiller number per plant and, therefore, restricted the development of horizontal space occupation. Annual neighbours did not cause an increase in tiller size, measured as lamina length or pseudostem height, but decreased root biomass. As a consequence, annual neighbours did not lead the hierarchy in light capture, but limited species radical colonization and competitive ability for soil resources. Winter nitrogen fertilization only affected tiller size in older tillers. These findings emphasize the importance of the cultural decisions, as sowing densities and nitrogen fertilization, to optimize pasture floristic composition.

Influences of stroma development on vegetative growth of Roegneria kamoji

Epichloë yangzii Li et Wang is a sexually reproducing, systemic fungal endophyte infecting the host grass Roegneria kamoji (Ohwi) Kent et Chen. To examine the effects of stromatal development on the host, R. kamoji plants harboring E. yangzii were collected from Jiangpu, Nanjing. Differences between stromatal plants and non-stromatal plants in terms of tillering and flowering of the plants, diameter and length of the culms, number and length of the leaves, and senescence of both leaves and culms were investigated from 2010 to 2012. Results indicate that stromal development of E. yangzii promoted the flag leaf growth of stromatal culms, enhanced thousand-seed weight of non-stromatal culms, delayed leaf and culm senescence of both stromatal and non-stromatal culms, but decreased tiller number and inhibited the emergence of inflorescence of the stromatal culms. The overgrowth of fungal hyphae blocked the emergence path and resulted in failure of the emergence of inflorescence of stromatal culms. The decrease in tiller number indicates that influences of stroma occur before plant vernalization, although stromata develop at the early stage of emergence of flag leaf sheath or inflorescence. The delay in leaf and culm senescence on the whole plants indicates signals caused by stromatal development, which can also be transferred to the non-stromatal tillers of the same plant. The mechanisms and significance of these influences, which are mediated by stromal development, need to be investigated in future research.

Control of Tiller Growth of Rice by OsSPL14 and Strigolactones, Which Work in Two Independent Pathways

The architecture of rice is greatly influenced by the growth of tillers, i.e. vegetative shoot branches. OsSPL14, a member of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes, and strigolactones (SLs) are known to suppress outgrowth of tiller buds. OsSPL14 also regulates panicle development. We show that OsSPL14 mRNA accumulates in leaf primordia during the vegetative phase and in the primordia of bracts, or modified leaves, in the panicles, but not in the meristems. OsSPL14 is a target of miR156, and accumulation of OsSPL14 transcripts is negatively regulated by miR156. The enhancement of the expression level of OsSPL14 by the introduction of the mOsSPL14 gene, in which the miR156 cleavage site is mutated, resulted in an increase in the plastochron, an acceleration of flowering and a decrease in tiller number in the wild type and in dwarf10-2, an SL-deficient mutant. Our analysis suggests that OsSPL14 and SLs function in parallel pathways to suppress tiller growth. SLs exuded from roots trigger germination of root parasitic plants that can cause severe damage to crop productivity. SL-deficient mutants, however, exhibit an excess branching phenotype which is usually undesirable for productivity. Our results indicate that OsSPL14 can be used to manipulate the branching patterns of SL-deficient mutants. We also confirmed that this strategy is applicable to Arabidopsis. A greater understanding of the OsSPL14 and SL pathways and their interactions may help in the production of root parasite-resistant crops.

The effects of feeding by the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on the growth and yield components of rice, Oryza sativa

Abstract 1 The effects of feeding by larvae of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, on the growth and yield components of rice, Oryza sativa, were evaluated using four varieties of rice, ‘Cocodrie’, ‘Cypress’, ‘Bengal’ and ‘XP1003’, over 2 years.2 Both adults and larvae of L. oryzophilus feed on rice plants, but it is feeding by the larval stage that causes economic losses. Feeding by L. oryzophilus larvae resulted in extensive damage to root systems. Pruning of root systems resulted in a decrease in tiller number and shoot biomass of rice plants in the vegetative stage of growth.3 Yield losses were due to a combination of decreases in panicle densities, numbers of grains per panicle, and grain weights. Decreases in panicle densities were a direct result of the reductions in tiller numbers. Reductions in numbers of grains per panicle and grain weights probably resulted from decreases in shoot biomass.4 Injury by rice water weevil larvae is chronic. The tillering stage of rice suffered the majority of weevil damage, but the growth effects were not manifested until later.

Losses in Wheat Due to Waterlogging

Waterlogging stress is one of the limiting factors influencing wheat (Triticum aestivum L.) production, especially in the lower Mississippi valley. A rain‐shelter experiment was designed to evaluate the trend response of nine wheat genotypes to four levels of waterlogging treatment: 0, 10, 20, and 30 d of flooding. Genotypes planted in polyvinilchloride (PVC) containers 25 cm long by 10 cm in diameter were waterlogged in plastic tanks under controlled rain conditions. Results indicated significant linear responses for kernels per head and tillers per plant, significant linear and quadratic responses for yield and chlorophyll content, and significant linear and cubic responses for plant height. The linear trend was the most important component, explaining from 92 to 99% of the variability due to waterlogging. Linear prediction equations were obtained to describe the relationship between different traits and waterlogging stress. Losses in yield and yield components were evaluated in a field experiment with 15 genotypes under control and waterlogging treatment. Average yield losses of 44% were mainly caused by a decrease in tiller number and kernels per head. Under waterlogging treatment, tiller number and kernels per head were reduced by 41 and 20%, respectively. Screening of wheat genotypes revealed the potential for waterlogging tolerance in breeding material and identified tolerant cultivars useful for waterlogged environments. ‘Terral LA 422’, ‘Shelby’, and ‘Pioneer 2691’ were the most adapted genotypes for waterlogging treatments. Because of a significant interaction with waterlogging treatment, some of the high‐yielding genotypes under non‐flooded conditions such as ‘Coker 9663’ and ‘FFR 502W’ showed low tolerance to waterlogging. The results provided information on the methods quantifying losses from waterlogging and identified selection criteria for waterlogging tolerance in wheat.

Losses in Wheat Due to Waterlogging

Waterlogging stress is one of the limiting factors influencing wheat (Triticum aestivum L.) production, especially in the lower Mississippi valley. A rain-shelter experiment was designed to evaluate the trend response of nine wheat genotypes to four levels of waterlogging treatment: 0, 10, 20, and 30 d of flooding. Genotypes planted in polyvinilchloride (PVC) containers 25 cm long by 10 cm in diameter were waterlogged in plastic tanks under controlled rain conditions. Results indicated significant linear responses for kernels per head and tillers per plant, significant linear and quadratic responses for yield and chlorophyll content, and significant linear and cubic responses for plant height. The linear trend was the most important component, explaining from 92 to 99% of the variability due to waterlogging. Linear prediction equations were obtained to describe the relationship between different traits and waterlogging stress. Losses in yield and yield components were evaluated in a field experiment with 15 genotypes under control and waterlogging treatment. Average yield losses of 44% were mainly caused by a decrease in tiller number and kernels per head. Under waterlogging treatment, tiller number and kernels per head were reduced by 41 and 20%, respectively. Screening of wheat genotypes revealed the potential for waterlogging tolerance in breeding material and identified tolerant cultivars useful for waterlogged environments. ‘Terral LA 422’, ‘Shelby’, and ‘Pioneer 2691’ were the most adapted genotypes for waterlogging treatments. Because of a significant interaction with waterlogging treatment, some of the high-yielding genotypes under non-flooded conditions such as ‘Coker 9663’ and ‘FFR 502W’ showed low tolerance to waterlogging. The results provided information on the methods quantifying losses from waterlogging and identified selection criteria for waterlogging tolerance in wheat.

Health care reform: The future of nursing

Lodging has been a major roadblock to attaining increased crop productivity. In an attempt to understand the mechanism for culm strength in rice, we isolated an effective quantitative trait locus (QTL), STRONG CULM3 (SCM3), the causal gene of which is identical to rice TEOSINTE BRANCHED1 (OsTB1), a gene previously reported to positively control strigolactone (SL) signaling. A near-isogenic line (NIL) carrying SCM3 showed enhanced culm strength and increased spikelet number despite the expected decrease in tiller number, indicating that SL also has a positive role in enhancing culm strength and spikelet number. We produced a pyramiding line carrying SCM3 and SCM2, another QTL encoding APO1 involved in panicle development. The NIL-SCM2+SCM3 showed a much stronger culm than NIL-SCM2 and NIL-SCM3 and an increased spikelet number caused by the additive effect of these QTLs. We discuss the importance of utilizing suitable alleles of these STRONG CULM QTLs without inducing detrimental traits for breeding.

The Effects of Benomyl on the Growth and Development of Wheat1

Wheat crops treated with benzimidazole‐containing fungicides have often shown small increases in yield in the absence of any detectable disease. This project was designed to test the possibility that direct physiological effects of the fungicide were responsible. The major effect of benomyl, at concentrations in the range 200–5000 ppm was to increase the development of tillers. Spraying at any one of several stages of development caused an increase in the number of tillers detected about 6 weeks later. This was found to be due to a more rapid initiation of tillers and not to more rapid growth following initiation. Associated with this earlier initiation was an increase in the incorporation of C14‐labelled assimilates into newly initiated tiller buds, but not into older ones. These responses resemble those reported for the effects of cytokinin applications to cereals. In field experiments, the increase in tiller production caused an increase in ear number only when plants were widely spaced. The decrease in tiller number as plant density increased was more rapid in treated plants than in controls, so that both treatments produced similar ear densities at around optimum plant density.

After-effect of photoperiodism in relation to development and yield of rice plant : (III) Effect of growth and time of heading of rice plant.

In the preceding paper, we reported on the premature heading caused by short-day treatment in seed-bed stage, with reference to the premature heading inductivity of the rice plant. Both in pot- and in field-experiments it was observed that the short-day treatment resulted in not only a induction of premature heading, but also delaying of the natural heading in the later period, in cases where the premature heading inductivity being large, the heading is much delayed. The long-day treatment combined with short-day seems to concel the delay of heading, although the effect of long-day alone was not always remarkable. The short-day treatment caused an increase in plant height and a decrease in number of tillers, in seed-bed, as compared with control plants. After transplantation a gradual decrease in height-growth and increase of number of tillers was observed. But the growth became vigorous again after the premature heading, and at the final stage the plant was slightly higher and evidently more tillers than the control plants. On the other hand the long-day treatment resulted in the lower plants having many tillers in seed-bed, but after transplantation the plant height increased and no more difference was observed between the treated and the control except the number of tillers was slightly few.