Controlling the trade-off between spikelet number and grain filling: the hierarchy of starch synthesis in spikelets of rice panicle in relation to hormone dynamics

2019 ◽  
Vol 46 (6) ◽  
pp. 507 ◽  
Author(s):  
Rashmi Panigrahi ◽  
Ekamber Kariali ◽  
Binay Bhusan Panda ◽  
Tanguy Lafarge ◽  
Pravat Kumar Mohapatra
Keyword(s):  
Ethylene Production ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Starch Biosynthesis ◽  
Yield Potential ◽  
Human Consumption ◽  
Spikelet Number ◽  
Trade Off ◽  
Inferior Spikelets ◽  
Endosperm Starch

The advent of dwarf statured rice varieties enabled a major breakthrough in yield and production, but raising the ceiling of genetically determined yield potential even further has been the breeding priority. Grain filling is asynchronous in the rice panicle; the inferior spikelets particularly on secondary branches of the basal part do not produce grains of a quality suitable for human consumption. Of the various strategies being considered, the control of ethylene production at anthesis has been a valuable route to potentially enhance genetic yield level of rice. The physiology underlying spikelet development has revealed spikelet position-specific ethylene levels determine the extent of grain filling, with higher levels resulting in ill-developed spikelet embodying poor endosperm starch content. To break the yield barrier, breeders have increased spikelet number per panicle in new large-panicle rice plants. However, the advantage of panicles with numerous spikelets has not resulted in enhanced yield because of poor filling of inferior spikelets. High spikelet number stimulates ethylene production and downgrading of starch synthesis, suggesting a trade-off between spikelet number and grain filling. High ethylene production in inferior spikelets suppresses expression of genes encoding endosperm starch synthesising enzymes. Hence, ethylene could be a retrograde signal that dictates the transcriptome dynamics for the cross talk between spikelet number and grain filling in the rice panicle, so attenuation of its activity may provide a solution to the problem of poor grain filling in large-panicle rice. This physiological linkage that reduces starch biosynthesis of inferior kernels is not genetically constitutive and amenable for modification through chemical, biotechnological, surgical and allelic manipulations. Studies on plant genotypes with different panicle architecture have opened up possibilities of selectively improving starch biosynthesis of inferior spikelets and thereby increasing grain yield through a physiological route.

Corrigendum to: Controlling the trade-off between spikelet number and grain filling: the hierarchy of starch synthesis in spikelets of rice panicle in relation to hormone dynamics

2019 ◽  
Vol 46 (6) ◽  
pp. 595 ◽  
Author(s):  
Rashmi Panigrahi ◽  
Ekamber Kariali ◽  
Binay Bhusan Panda ◽  
Tanguy Lafarge ◽  
Pravat Kumar Mohapatra
Keyword(s):  
Ethylene Production ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Starch Biosynthesis ◽  
Yield Potential ◽  
Human Consumption ◽  
Spikelet Number ◽  
Trade Off ◽  
Inferior Spikelets ◽  
Endosperm Starch

The advent of dwarf statured rice varieties enabled a major breakthrough in yield and production, but raising the ceiling of genetically determined yield potential even further has been the breeding priority. Grain filling is asynchronous in the rice panicle; the inferior spikelets particularly on secondary branches of the basal part do not produce grains of a quality suitable for human consumption. Of the various strategies being considered, the control of ethylene production at anthesis has been a valuable route to potentially enhance genetic yield level of rice. The physiology underlying spikelet development has revealed spikelet position-specific ethylene levels determine the extent of grain filling, with higher levels resulting in ill-developed spikelet embodying poor endosperm starch content. To break the yield barrier, breeders have increased spikelet number per panicle in new large-panicle rice plants. However, the advantage of panicles with numerous spikelets has not resulted in enhanced yield because of poor filling of inferior spikelets. High spikelet number stimulates ethylene production and downgrading of starch synthesis, suggesting a trade-off between spikelet number and grain filling. High ethylene production in inferior spikelets suppresses expression of genes encoding endosperm starch synthesising enzymes. Hence, ethylene could be a retrograde signal that dictates the transcriptome dynamics for the cross talk between spikelet number and grain filling in the rice panicle, so attenuation of its activity may provide a solution to the problem of poor grain filling in large-panicle rice. This physiological linkage that reduces starch biosynthesis of inferior kernels is not genetically constitutive and amenable for modification through chemical, biotechnological, surgical and allelic manipulations. Studies on plant genotypes with different panicle architecture have opened up possibilities of selectively improving starch biosynthesis of inferior spikelets and thereby increasing grain yield through a physiological route.

Identification of Novel QTLs for Spikelet Fertility, Panicle Compactness and Phytohormone Ethylene to Decipher Poor Grain Filling of Basal Spikelets in Dense Panicle Rice

2021 ◽  
Author(s):  
Sudhanshu Sekhar ◽  
Jitendra Kumar ◽  
Soumya Mohanty ◽  
Niharika Mohanty ◽  
Rudraksh Shovan Panda ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Ethylene Production ◽  
Recombinant Inbred Lines ◽  
Grain Filling ◽  
Spikelet Fertility ◽  
Rice Cultivars ◽  
Spikelet Number ◽  
Spikelet Sterility ◽  
Ubiquitin Protein Ligase ◽  
Comparative Expression Analysis

Abstract High grain number is positively correlated with grain yield in rice, but it is compromised because of poor filling of basal spikelets in dense panicle bearing numerous spikelets. The phenomenon that turns the basal spikelets of compact panicle sterile in rice is largely unknown. In order to understand the factor(s) that possibly determines such spikelet sterility in compact panicle cultivars, QTLs and candidate genes were identified for spikelet fertility percentage, panicle compactness and ethylene production that significantly influence the grain filling using recombinant inbred lines developed from a cross between indica rice cultivars, PDK Shriram (compact, high spikelet number) and Heera (lax, low spikelet number). Novel QTLs, qSFP1.1, qSFP3.1 and qSFP6.1 for spikelet fertility percentage; qIGS3.2 and qIGS4.1 for panicle compactness; and qETH1.2, qETH3.1 and qETH4.1 for ethylene production were consistently identified in both kharif seasons of 2017 and 2018. The comparative expression analysis of candidate genes like ERF3, AP2-like ethylene-responsive transcription factor, EREBP, GBSS1, E3 ubiquitin-protein ligase GW2, and LRR receptor-like serine/threonine-protein kinase ERL1 associated with identified QTLs revealed their role in poor grain filling of basal spikelets in dense panicle. These candidate genes thus could be important for improving grain filling in compact-panicle rice cultivars through biotechnological interventions.

scholarly journals Introgression of Sub1 (SUB1) QTL in mega rice cultivars increases ethylene production to the detriment of grain- filling under stagnant flooding

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sandhya Rani Kuanar ◽  
Kutubuddin Ali Molla ◽  
Krishnendu Chattopadhyay ◽  
Ramani Kumar Sarkar ◽  
Pravat Kumar Mohapatra
Keyword(s):  
Grain Yield ◽  
Ethylene Production ◽  
Stem Elongation ◽  
Starch Synthesis ◽  
Acc Oxidase ◽  
Acc Synthase ◽  
Grain Filling ◽  
Soluble Carbohydrates ◽  
Rice Cultivars ◽  
Oxidase Enzyme

AbstractIn the recent time, Submergence1 (Sub1)QTL, responsible for imparting tolerance to flash flooding, has been introduced in many rice cultivars, but resilience of the QTL to stagnant flooding (SF) is not known. The response of Sub1-introgression has been tested on physiology, molecular biology and yield of two popular rice cultivars (Swarna and Savitri) by comparison of the parental and Sub1-introgression lines (SwarnaSub1 and SavitriSub1) under SF. Compared to control condition SF reduced grain yield and tiller number and increased plant height and Sub1- introgression mostly matched these effects. SF increased ethylene production by over-expression of ACC-synthase and ACC-oxidase enzyme genes of panicle before anthesis in the parental lines. Expression of the genes changed with Sub1-introgression, where some enzyme isoform genes over-expressed after anthesis under SF. Activities of endosperm starch synthesizing enzymes SUS and AGPase declined concomitantly with rise ethylene production in the Sub1-introgressed lines resulting in low starch synthesis and accumulation of soluble carbohydrates in the developing spikelets. In conclusion, Sub1-introgression into the cultivars increased susceptibility to SF. Subjected to SF, the QTL promoted genesis of ethylene in the panicle at anthesis to the detriment of grain yield, while compromising with morphological features like tiller production and stem elongation.

scholarly journals OsPK2encodes a plastidic pyruvate kinase involved in rice endosperm starch synthesis, compound granule formation and grain filling

2018 ◽  
Vol 16 (11) ◽  
pp. 1878-1891 ◽  
Author(s):  
Yicong Cai ◽  
Sanfeng Li ◽  
Guiai Jiao ◽  
Zhonghua Sheng ◽  
Yawen Wu ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Granule Formation ◽  
Rice Endosperm ◽  
Endosperm Starch

scholarly journals GC-MS-based metabolite profiling of key differential metabolites between superior and inferior spikelets of rice during the grain filling stage

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiumei Min ◽  
Hailong Xu ◽  
Fenglian Huang ◽  
Yidong Wei ◽  
Wenxiong Lin ◽  
...  
Keyword(s):  
Soluble Sugars ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Absolute Quantification ◽  
Metabolite Level ◽  
Inferior Spikelets ◽  
Expression Of Genes ◽  
Grain Filling Rate ◽  
Proteome Level ◽  
The Difference

Abstract Background The asynchronous filling between superior spikelets (SS) and inferior spikelets (IS) in rice has become a research hotspot. The stagnant development and poor grain filling of IS limit yields and the formation of good quality rice. A large number of studies on this phenomenon have been carried out from the genome, transcriptome and proteome level, indicating that asynchronous filling of SS and IS filling is a complex, but orderly physiological and biochemical process involving changes of a large number of genes, protein expression and modification. However, the analysis of metabolomics differences between SS and IS is rarely reported currently. Results This study utilized untargeted metabolomics and identified 162 metabolites in rice spikelets. Among them, 17 differential metabolites associated with unsynchronized grain filling between SS and IS, 27 metabolites were related to the stagnant development of IS and 35 metabolites related to the lower maximum grain-filling rate of IS compared with the SS. We found that soluble sugars were an important metabolite during grain filling for SS and IS. Absolute quantification was used to further analyze the dynamic changes of 4 types of soluble sugars (sucrose, fructose, glucose, and trehalose) between SS and IS. The results showed that sucrose and trehalose were closely associated with the dynamic characteristics of grain filling between SS and IS. The application of exogenous sugar showed that trehalose functioned as a key sugar signal during grain filling of IS. Trehalose regulated the expression of genes related to sucrose conversion and starch synthesis, thereby promoting the conversion of sucrose to starch. The difference in the spatiotemporal expression of TPS-2 and TPP-1 between SS and IS was an important reason that led to the asynchronous change in the trehalose content between SS and IS. Conclusions The results from this study are helpful for understanding the difference in grain filling between SS and IS at the metabolite level. In addition, the present results can also provide a theoretical basis for the next step of using metabolites to regulate the filling of IS.

scholarly journals GC-MS-Based Metabolite Profiling of Key Differential Metabolites Between Superior and Inferior Spikelets of Rice During the Grain Filling Stage

2021 ◽  
Author(s):  
Xiumei Min ◽  
Hailong Xu ◽  
Fenglian Huang ◽  
Yidong Wei ◽  
Wenxiong Lin ◽  
...  
Keyword(s):  
Soluble Sugars ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Absolute Quantification ◽  
Metabolite Level ◽  
Inferior Spikelets ◽  
Expression Of Genes ◽  
Proteome Level ◽  
Superior Spikelets ◽  
The Difference

Abstract Background:The asynchronous filling between superior spikelets (SS) and inferior spikelets (IS) in rice has become a research hotspot. The stagnant development and poor grain filling of IS limit yields and the formation of good quality rice. A large number of studies on this phenomenon have been carried out from the genome, transcriptome and proteome level, indicating that asynchronous filling of SS and IS filling is a complex, but orderly physiological and biochemical process involving changes of a large number of genes, protein expression and modification. However, the analysis of metabolomics differences between SS and IS is rarely reported currently.Results:This study utilized untargeted metabolomics and identified 162 metabolites in rice spikelets. Among them, 17 differential metabolites associated with unsynchronized grain filling between superior spikelets (SS) and IS, 27 metabolites were related to the stagnant development of IS and 35 metabolites related to the lower maximum grain-filling rate of IS compared with the SS. We found that soluble sugars were an important metabolite during grain filling for SS and IS. Absolute quantification was used to further analyze the dynamic changes of 4 types of soluble sugars (sucrose, fructose, glucose, and trehalose) between SS and IS. The results showed that sucrose and trehalose were closely associated with the dynamic characteristics of grain filling between SS and IS. The application of exogenous sugar showed that trehalose functioned as a key sugar signal during grain filling. Trehalose regulated the expression of genes related to sucrose conversion and starch synthesis, thereby promoting the conversion of sucrose to starch. The difference in the spatiotemporal expression of TPS-2 and TPP-1 between SS and IS was an important reason that led to the difference in trehalose contents between SS and IS.Conclusions:The results from this study are helpful for understanding the difference in grain filling between SS and IS at the metabolite level. In addition, the present results can also provide a theoretical basis for the next step of using metabolites to regulate the filling of IS.

scholarly journals Efficiency of Sucrose to Starch Metabolism Is Related to the Initiation of Inferior Grain Filling in Large Panicle Rice

2021 ◽  
Vol 12 ◽  
Author(s):  
Zhengrong Jiang ◽  
Qiuli Chen ◽  
Lin Chen ◽  
Hongyi Yang ◽  
Meichen Zhu ◽  
...  
Keyword(s):  
Oryza Sativa ◽  
Field Experiment ◽  
Expression Patterns ◽  
Grain Filling ◽  
Yield Potential ◽  
Sugar Signaling ◽  
Starch Metabolism ◽  
Rice Varieties ◽  
Inferior Spikelets ◽  
The Poor

The poor grain-filling initiation often causes the poor development of inferior spikelets (IS) which limits the yield potential of large panicle rice (Oryza sativa L.). However, it remains unclear why IS often has poor grain-filling initiation. In addressing this problem, this study conducted a field experiment involving two large panicle rice varieties, namely CJ03 and W1844, in way of removing the superior spikelets (SS) during flowering to force enough photosynthate transport to the IS. The results of this study showed that the grain-filling initiation of SS was much earlier than the IS in CJ03 and W1844, whereas the grain-filling initiation of IS in W1844 was evidently more promoted compared with the IS of CJ03 by removing spikelets. The poor sucrose-unloading ability, i.e., carbohydrates contents, the expression patterns of OsSUTs, and activity of CWI, were highly improved in IS of CJ03 and W1844 by removing spikelets. However, there was a significantly higher rise in the efficiency of sucrose to starch metabolism, i.e., the expression patterns of OsSUS4 and OsAGPL1 and activities of SuSase and AGPase, for IS of W1844 than that of CJ03. Removing spikelets also led to the changes in sugar signaling of T6P and SnRK1 level. These changes might be related to the regulation of sucrose to starch metabolism. The findings of this study suggested that poor sucrose-unloading ability delays the grain-filling initiation of IS. Nonetheless, the efficiency of sucrose to starch metabolism is also strongly linked with the grain-filling initiation of IS.

scholarly journals Identification of novel QTLs for grain fertility and associated traits to decipher poor grain filling of basal spikelets in dense panicle rice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sudhanshu Sekhar ◽  
Jitendra Kumar ◽  
Soumya Mohanty ◽  
Niharika Mohanty ◽  
Rudraksh Shovan Panda ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Ethylene Production ◽  
Recombinant Inbred Lines ◽  
Grain Filling ◽  
Spikelet Fertility ◽  
Rice Cultivars ◽  
Spikelet Number ◽  
Spikelet Sterility ◽  
Ubiquitin Protein Ligase ◽  
Comparative Expression Analysis

AbstractHigh grain number is positively correlated with grain yield in rice, but it is compromised because of poor filling of basal spikelets in dense panicle bearing numerous spikelets. The phenomenon that turns the basal spikelets of compact panicle sterile in rice is largely unknown. In order to understand the factor(s) that possibly determines such spikelet sterility in compact panicle cultivars, QTLs and candidate genes were identified for spikelet fertility and associated traits like panicle compactness, and ethylene production that significantly influences the grain filling using recombinant inbred lines developed from a cross between indica rice cultivars, PDK Shriram (compact, high spikelet number) and Heera (lax, low spikelet number). Novel QTLs, qSFP1.1, qSFP3.1, and qSFP6.1 for spikelet fertility percentage; qIGS3.2 and qIGS4.1 for panicle compactness; and qETH1.2, qETH3.1, and qETH4.1 for ethylene production were consistently identified in both kharif seasons of 2017 and 2018. The comparative expression analysis of candidate genes like ERF3, AP2-like ethylene-responsive transcription factor, EREBP, GBSS1, E3 ubiquitin-protein ligase GW2, and LRR receptor-like serine/threonine-protein kinase ERL1 associated with identified QTLs revealed their role in poor grain filling of basal spikelets in a dense panicle. These candidate genes thus could be important for improving grain filling in compact-panicle rice cultivars through biotechnological interventions.

Post-Anthesis Changes in Concentrations of Polyamines in Superior and Inferior Spikelets and Their Relation with Grain Filling of Super Rice

2009 ◽  
Vol 35 (12) ◽  
pp. 2225-2233 ◽  
Author(s):  
Gui-Lu TAN ◽  
Hao ZHANG ◽  
Jing FU ◽  
Zhi-Qin WANG ◽  
Li-Jun LIU ◽  
...  
Keyword(s):  
Grain Filling ◽  
Inferior Spikelets
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