Mutation of ONAC096 Enhances Grain Yield by Increasing Panicle Number and Delaying Leaf Senescence during Grain Filling in Rice

Exploring genetic methods to improve yield in grain crops such as rice (Oryza sativa) is essential to help meet the needs of the increasing population. Here, we report that rice ONAC096 affects grain yield by regulating leaf senescence and panicle number. ONAC096 expression increased rapidly in rice leaves upon the initiation of aging- and dark-induced senescence. Two independent T-DNA insertion mutants (onac096-1 and onac096-2) with downregulated ONAC096 expression retained their green leaf color during natural senescence in the field, thus extending their photosynthetic capacity. Reverse-transcription quantitative PCR analysis showed that ONAC096 upregulated genes controlling chlorophyll degradation and leaf senescence. Repressed OsCKX2 (encoding cytokinin oxidase/dehydrogenase) expression in the onac096 mutants led to a 15% increase in panicle number without affecting grain weight or fertility. ONAC096 mediates abscisic acid (ABA)-induced leaf senescence by upregulating the ABA signaling genes ABA INSENSITIVE5 and ENHANCED EM LEVEL. The onac096 mutants showed a 16% increase in grain yield, highlighting the potential for using this gene to increase grain production.

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Rate and duration of grain filling in relation to flag leaf senescence and grain yield in spring wheat (Triticum aestivum) exposed to different concentrations of ozone

Physiologia Plantarum ◽

10.1111/j.1399-3054.2000.1100311.x ◽

2008 ◽

Vol 110 (3) ◽

pp. 366-375 ◽

Cited By ~ 1

Author(s):

Johanna Gelang ◽

Håkan Pleijel ◽

Ebe Sild ◽

Helena Danielsson ◽

Suhaila Younis ◽

...

Keyword(s):

Triticum Aestivum ◽

Grain Yield ◽

Leaf Senescence ◽

Spring Wheat ◽

Flag Leaf ◽

Grain Filling

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Heat stress in grain legumes during reproductive and grain-filling phases

Crop and Pasture Science ◽

10.1071/cp17012 ◽

2017 ◽

Vol 68 (11) ◽

pp. 985 ◽

Cited By ~ 18

Author(s):

Muhammad Farooq ◽

Faisal Nadeem ◽

Nirmali Gogoi ◽

Aman Ullah ◽

Salem S. Alghamdi ◽

...

Keyword(s):

Heat Stress ◽

High Temperature ◽

Grain Yield ◽

Leaf Senescence ◽

Management Strategies ◽

Substantial Reduction ◽

Grain Filling ◽

Grain Legumes ◽

Grain Legume ◽

The Impact

Thermal stress during reproductive development and grain-filling phases is a serious threat to the quality and productivity of grain legumes. The optimum temperature range for grain legume crops is 10−36°C, above which severe losses in grain yield can occur. Various climatic models have simulated that the temperature near the earth’s surface will increase (by up to 4°C) by the end of this century, which will intensify the chances of heat stress in crop plants. The magnitude of damage or injury posed by a high-temperature stress mainly depends on the defence response of the crop and the specific growth stage of the crop at the time of exposure to the high temperature. Heat stress affects grain development in grain legumes because it disintegrates the tapetum layer, which reduces nutrient supply to microspores leading to premature anther dehiscence; hampers the synthesis and distribution of carbohydrates to grain, curtailing the grain-filling duration leading to low grain weight; induces poor pod development and fractured embryos; all of which ultimately reduce grain yield. The most prominent effects of heat stress include a substantial reduction in net photosynthetic rate, disintegration of photosynthetic apparatus and increased leaf senescence. To curb the catastrophic effect of heat stress, it is important to improve heat tolerance in grain legumes through improved breeding and genetic engineering tools and crop management strategies. In this review, we discuss the impact of heat stress on leaf senescence, photosynthetic machinery, assimilate translocation, water relations, grain quality and development processes. Furthermore, innovative breeding, genetic, molecular and management strategies are discussed to improve the tolerance against heat stress in grain legumes.

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CRITICAL VARIABLES OF MORPHO-PHYSIOLOGICAL RICE PLANT UNDER STAGNANT FLOODING CONDITIONS

Indonesian Journal of Agricultural Science ◽

10.21082/ijas.v22n1.2021.p1-7 ◽

2021 ◽

Vol 22 (1) ◽

pp. 1

Author(s):

Nurwulan Agustiani ◽

Sujinah Sujinah ◽

Indrastuti Apri Rumanti

Keyword(s):

Grain Yield ◽

Water Depth ◽

Rice Yield ◽

Irrigation System ◽

Block Design ◽

Grain Filling ◽

System Control ◽

New Variety ◽

Panicle Number ◽

The Impact

<p class="abstrakinggris"><span lang="EN-US">Stagnant flooding (SF) stress has contributed decreasing rice production in Indonesia. The study aimed to explore critical variables of rice growth that contribute to the decreasing grain yield under SF conditions and a common irrigation system (control). The experiment was arranged in a complete randomized block design with four replications to test 10 rice genotypes (Inpari 30 Ciherang Sub-1, Inpara 3, Inpara 4, Inpara 8, IRRI119, IRRI154, IR42, IR14D121, IR14D157, and Tapus). The water depth was managed according to the farmer’s practices for control, while for SF plots the standing water depth was gradually increased from 35 days after transplanting and was maintained at 50 cm until harvest. Results showed that plant height, tillering ability, leaf greenness, panicle number per hill and grain filling percentage were critical growth variables that affect grain yield at optimal conditions. The yield of the 10 genotypes decreased by 25–50% under SF conditions. Inpara 3 had the stable yield in those two watering conditions. Therefore, it could be used as a check variety for SF condition. Inpara 9 and IRRI119 experienced decreased yield of more than 50% under SF conditions. The key factors determining the decreased yield were tillering ability and green leaf level. Optimization of the two variables at SF conditions will largely determine rice yield associated with panicle number per hill and grain number per panicle. Results of the study are useful as preliminary recommendations for designing new variety and cultivation techniques to reduce the impact of SF stress on rice yield.</span></p>

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Nitrogen deficiency regulates premature senescence by modulating flag leaf function, ROS homeostasis, and intercellular sugar concentration in rice during grain filling

Journal of Genetic Engineering and Biotechnology ◽

10.1186/s43141-021-00275-3 ◽

2021 ◽

Vol 19 (1) ◽

Author(s):

Shamsu Ado Zakari ◽

Syed Hassan Raza Zaidi ◽

Mustapha Sunusi ◽

Kabiru Dawaki Dauda

Keyword(s):

Grain Yield ◽

Leaf Senescence ◽

Flag Leaf ◽

Grain Filling ◽

Sugar Concentration ◽

Premature Senescence ◽

N Supply ◽

Ros Homeostasis ◽

N Assimilation ◽

N Deficiency

Abstract Background Leaf senescence occurs in an age-dependent manner, but the rate and timing of leaf senescence may be influenced by various biotic and abiotic factors. In the course of stress, the function, composition, and different components of photosynthetic apparatus occur to be synthesized homogeneously or degraded paradoxically due to different senescence-related processes. Nitrogen (N) deficiency is one of the critical environmental factors that induce leaf senescence, and its incidence may curtail leaf photosynthetic function and markedly alter the genetic information of plants that might result in low grain yield. However, the physiological and genetic mechanism underlying N deficiency regulates premature senescence, and flag leaf function, ROS homeostasis, and intercellular sugar concentration in rice during grain filling are not well understood. In this paper, Zhehui7954 an excellent indica restorer line (wildtype) and its corresponding mutant (psf) with the premature senescence of flag leaves were used to study the effect of different N supplies in the alteration of physiological and biochemical components of flag leaf organ and its functions during grain filling. Results The results showed that the psf mutant appeared to be more susceptible to the varying N supply levels than WT. For instance, the psf mutant showed considerably lower Pn, Chl a, Chl b, and Car contents than its WT. N deficiency (LN) decreased leaves photosynthetic activities, N metabolites, but significantly burst O2•−, H2O2, and relative conductivity (R1/R2) concentrations, which was consistent with the expression levels of senescence-associated genes. Sucrose, glucose, and C/N ratio concentrations increased with a decrease in N level, which was closely associated with N and non-structural carbohydrate translocation rates. Increases in POD activity were positively linked with the senescence-related enhancement of ROS generation under LN conditions, whereas, SOD, CAT, and APX activities showed opposite trends. High N (HN) supply significantly inhibits the transcripts of carbohydrate biosynthesis genes, while N assimilation gene transcripts gradually increased along with leaf senescence. The psf mutant had a relatively higher grain yield under HN treatment than LN, while WT had a higher grain yield under MN than HN and LN. Conclusions This work revealed that the C/N ratio and ROS undergo a gradual increase driven by interlinking positive feedback, providing a physiological framework connecting the participation of sugars and N assimilation in the regulation of leaf senescence. These results could be useful for achieving a higher yield of rice production by appropriate N supply and plant senescence regulation.

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The relationship between flag leaf senescence and grain yield of some durum wheat varieties under drought stress during grain filling period

Tarım Bilimleri Dergisi ◽

10.1501/tarimbil_0000001341 ◽

2015 ◽

Vol 21 (3) ◽

pp. 382-393

Author(s):

TİRYAKİOĞLU Murat

Keyword(s):

Drought Stress ◽

Grain Yield ◽

Durum Wheat ◽

Leaf Senescence ◽

Flag Leaf ◽

Grain Filling ◽

Wheat Varieties ◽

Grain Filling Period ◽

The Relationship

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Oat (Avena sativa) yield and grain fill responses to varying agronomic and weather factors

The Journal of Agricultural Science ◽

10.1017/s0021859621000320 ◽

2021 ◽

pp. 1-16

Author(s):

C. P. McCabe ◽

J. I. Burke

Keyword(s):

Grain Yield ◽

Yield Components ◽

Grain Filling ◽

Seasonal Effects ◽

Plant Responses ◽

Weather Factors ◽

Seed Rate ◽

Panicle Number ◽

Positive Correlations ◽

Yield Formation

Abstract Factorial experiments were carried out on spring- and winter-sown oat crops in Ireland in 2016–2019 to identify plant responses in yield formation and grain filling procedures. Two cultivars (Husky and Keely), three seed rates (250, 350 and 450 seeds/m2), six applied nitrogen (N) rates (40, 70, 100, 130, 160 and 190 kg N/ha) with a plant growth regulator (PGR) were examined in spring and winter sowings, using the same cultivars at five rates of applied N (80, 110, 140, 170 and 200 kg N/ha). The applied N rate and seed rate significantly (P < 0.05) modified the yield components determining grains/m2 in spring- and winter-sown crops with increases in panicle number of key importance. Increases were also observed in the proportion of primary grain by weight (0.9–1.6%) and number (0.7–1.4%) ratios in spring-sown crops in response to applied N rate, with winter-sown crops exhibiting a more consistent pattern of grain fill. Seed rate and PGR application had minor effects on yield components and panicle conformation. Grain fill procedures played an important role in the maximization of grain yield under seasonal conditions. Significant positive correlations were observed between the number of aborted grain sites and yield under drought conditions (0.22), with negative associations observed in near-optimal conditions (−0.22 to −0.41). Agronomic effects on grain site abortion were minimal in comparison with seasonal effects. In seasons characterized by cool, consistent conditions, grain yield was maximized by the utilization of all available grain sites. Where assimilate shortages were encountered during grain fill the abortion of grains sites was positively associated with grain yield.

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Paclobutrazol Application Favors Yield Improvement of Maize Under Semiarid Regions by Delaying Leaf Senescence and Regulating Photosynthetic Capacity and Antioxidant System During Grain-Filling Stage

Agronomy ◽

10.3390/agronomy10020187 ◽

2020 ◽

Vol 10 (2) ◽

pp. 187 ◽

Cited By ~ 3

Author(s):

Muhammad Kamran ◽

Shakeel Ahmad ◽

Irshad Ahmad ◽

Izhar Hussain ◽

Xiangping Meng ◽

...

Keyword(s):

Grain Yield ◽

Leaf Senescence ◽

Photosynthetic Rate ◽

Grain Filling ◽

Yield Improvement ◽

Chlorophyll Contents ◽

Maize Seeds ◽

Kernel Weights ◽

Ros Burst ◽

Grain Filling Period

In the present study, we examined the potential role of paclobutrazol in delaying leaf senescence, in causing changes in the activities of antioxidants, and in the maintenance of photosynthetic activity during the senescence process, and, therefore, on the grain yield of maize under semiarid field conditions. Maize seeds were pretreated with 0 (CK), 200 (PS1), 300 (PS2), and 400 (PS3) mg paclobutrazol L−1. Our results indicated that elevated levels of reactive oxygen species (ROS) and higher accumulation of malondialdehyde (MDA) contents were positively associated with accelerated leaf senescence during the grain-filling periods. The leaf senescence resulted in the disintegration of the photosynthetic pigments and reduced the net photosynthetic rate after silking. However, the resultant ROS burst (O2− and H2O2) was lessened and the leaf senescence and chlorophyll degradation were evidently inhibited in leaves of paclobutrazol-treated maize plants, which was strongly linked with upregulated activities of antioxidant enzymes in treated plants. The enhanced chlorophyll contents and availability of a greater photosynthetic active green leaf area during the grain filling period facilitated the maintenance of higher photosynthetic rate, and light-harvesting efficiency of photosynthesis associated with photosystem II (PSII) resulted in higher kernel number ear−1 and thousand kernel weights, and thus increased the final grain yield. The average maize grain yield was increased by 18.8% to 55.6% in paclobutrazol treatments, compared to untreated control. Among the various paclobutrazol treatments, PS2 (300 mg L−1) treatment showed the most promising effects on enhancing the activities of antioxidative enzymes, delaying leaf senescence and improving the yield of maize. Thus, understanding this effect of paclobutrazol on delaying leaf senescence introduces new possibilities for facilitating yield improvement of maize under semiarid conditions.

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Rice DNA-Binding One Zinc Finger 24 (OsDOF24) Delays Leaf Senescence in a Jasmonate-Mediated Pathway

Plant and Cell Physiology ◽

10.1093/pcp/pcz105 ◽

2019 ◽

Vol 60 (9) ◽

pp. 2065-2076 ◽

Cited By ~ 6

Author(s):

Yejin Shim ◽

Kiyoon Kang ◽

Gynheung An ◽

Nam-Chon Paek

Keyword(s):

Dna Binding ◽

Zinc Finger ◽

Leaf Senescence ◽

Agronomic Traits ◽

Grain Filling ◽

Cereal Crops ◽

Pcr Analysis ◽

Physiological Processes ◽

Leaf Yellowing ◽

Senescence Associated Genes

Abstract Leaf senescence is the final stage of leaf development and in cereal crops, the timing of senescence relative to grain filling has major effects on agronomic traits such as yield. Although many genetic factors are involved in the regulation of leaf senescence in cereals, the key regulators remain to be determined. Plant transcription factors with a conserved DOF (DNA-binding one zinc finger) domain play roles in multiple physiological processes. Here, we show a novel function for OsDOF24 as a repressor of leaf senescence in rice (Oryza sativa). In wild-type leaves, OsDOF24 expression rapidly decreased during natural senescence (NS) and dark-induced senescence (DIS). The gain-of-function mutant osdof24-D, which contains an enhancer-trap T-DNA in the OsDOF24 promoter, exhibited delayed leaf yellowing during NS and DIS. Transgenic plants overexpressing OsDOF24 showed the same phenotype during DIS. Reverse-transcription quantitative real-time PCR analysis revealed that senescence-associated genes (Osl85, Osl57 and OsNAP) and chlorophyll degradation genes (NYC1, NYC3 and SGR) were downregulated in the osdof24-D mutant during dark incubation. Among the phytohormones, only methyl jasmonate induced OsDOF24 expression. Furthermore, the reduced expression of jasmonate biosynthesis-related genes (OsLOX2, OsLOX8, OsHI-LOX, OsAOS1 and OsAOS2) in osdof24-D decreased endogenous jasmonate levels, resulting in delayed leaf senescence under DIS conditions. Yeast one-hybrid assays showed that OsDOF24 binds to the promoter region of OsAOS1. Taken together, our results demonstrate that OsDOF24 suppresses the induction of leaf senescence during vegetative growth by deactivating jasmonate biosynthetic pathways.

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Effect of late nitrogen application on growth and nitrogen balance of two cultivars of water-stressed grain sorghum

Australian Journal of Agricultural Research ◽

10.1071/a97120 ◽

1998 ◽

Vol 49 (4) ◽

pp. 687 ◽

Cited By ~ 4

Author(s):

S. B. Utzurrum Jr ◽

S. Fukai ◽

M. A. Foale

Keyword(s):

Water Stress ◽

Grain Yield ◽

Leaf Senescence ◽

Osmotic Adjustment ◽

Dry Matter ◽

Grain Filling ◽

Middle Layer ◽

N Application ◽

Green Leaves ◽

Rainout Shelter

With development of water stress during grain filling, sorghum crops lose green leaves, and nitrogen (N) is remobilised from the leaves to grain. Supplementary N application just before anthesis may reduce leaf senescence, contributing to dry matter production during grain filling and, hence, grain yield. This hypothesis was tested using 2 sorghum hybrids which were known to differ in capacity for osmotic adjustment and the ability to retain green leaves under water stress, in a rainout shelter experiment in south-east Queensland. When N was applied at depth (>70 cm) where water was available, all N applied was apparently taken up by the plants, resulting in reduced leaf senescence, particularly for leaves in the middle layer. Remobilisation of N from leaf to grain during grain filling was reduced by the supplementary N application. Both stem and leaf were the source of remobilised N which contributed about 65% of the total grain N without supplementary N application, this being reduced to about 30% with N application The hybrid with known high osmotic adjustment had greater total above-ground dry matter, particularly stem dry matter, at anthesis than the other, providing more material for translocation to fill grains. It also maintained greater leaf area during early stages of grain filling. This hybrid produced significantly higher yield (465 v. 412 g/m2) only when supplementary N was applied. Without supplementary N application, their yields were similar at about 350 g/m2. It is concluded that provided N is taken up by the sorghum plants, late N application is effective in increasing grain yield under water-limiting conditions. Cultivars, however, differed in their responses to the application.

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