Changes in the Chlorophyll Content and Cytokinin Levels in the Top Three Leaves of New Plant Type Rice During Grain Filling

Rubia, L.; Rangan, Latha; Choudhury, Rimjhim Roy; Kamínek, M.; Dobrev, Petre I.; Malbeck, Jiří; Fowler, Mark R.; Slater, A.; Scott, Nigel W.; Bennett, John; Peng, Shaobing; Khush, G. S.; Elliott, Malcolm C.

doi:10.1007/s00344-013-9374-0

Cited by 13 publications

(10 citation statements)

References 57 publications

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“…Leaf senescence is the final stage of leaf development and is critical for grain-yield formation because it affects the assimilate supply and plant fitness. A good deal of evidence has been provided on the favorable virtues of delayed leaf senescence, which is characterized by enhanced photosynthesis, increased chlorophyll, and soluble protein contents, and the decreased degradation of organelles could contribute to higher grain weights and grain yields (Jibran et al, 2013;Rubia et al, 2014;Zhang et al, 2015). A good deal of evidence has been provided on the favorable virtues of delayed leaf senescence, which is characterized by enhanced photosynthesis, increased chlorophyll, and soluble protein contents, and the decreased degradation of organelles could contribute to higher grain weights and grain yields (Jibran et al, 2013;Rubia et al, 2014;Zhang et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Application of Salicylic Acid Improves Filling of Inferior Grains of Rice during Late Maturity under Mild Cold Stress

et al. 2017

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Medium‐ or late‐maturing varieties of rice (Oryza sativa L.) that are planted in agroecosystems in the middle and lower reaches of the Yangtze Valley of China always encounter cold stress during the late grain‐filling stage. Generally, grain yield and yield components are adversely affected under such circumstances. To alleviate these negative effects, salicylic acid (SA; i.e., SA0 [control, 0 mg L−1], SA100 [100 mg L−1], SA200 [200 mg L−1], SA300 [300 mg L−1], and SA400 [400 mg L−1]) was exogenously sprayed on plants of three rice cultivars at full heading in the field at the experimental base of China National Rice Research Institute (CNRRI) in Fuyang City, China (30°03′ N, 119°57′ E, 11 m asl). The results indicated that the mean grain‐filling rate and grain weight of the inferior grains were significantly increased under the SA200 (200 mg L−1) treatment and correspondingly contributed to a grain yield increase of 5.0 to 10.1% in comparison with the control. Further analysis showed that the SA200 treatment significantly increased the activity of the starch branching enzyme in inferior grains over the entire grain‐filling stage. Additionally, the photosynthetic rate, chlorophyll content, and soluble protein content of the flag leaf, which precisely reflected the senescence status, were significantly increased under the SA200 treatment, especially during late maturity under mild cold stress. We speculated that improved physiological changes during the late grain‐filling stage account for the increased grain weight and grain yield. Therefore, application of SA was a promising method of alleviating the adverse effects that were induced by mild cold stress on the grain yield of rice in the middle and lower reaches of the Yangtze Valley of China.

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Section: Discussionmentioning

confidence: 99%

Application of Salicylic Acid Improves Filling of Inferior Grains of Rice during Late Maturity under Mild Cold Stress

et al. 2017

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“…shows that leaf proteins in the intact plants were depleted in both cultivars – although at different kinetics – at 20 and 25 dpa, a response that was prevented greatly in Sakha 101 but slightly (if any) in IR64 by detillering. Depletion of leaf proteins could mark the onset of leaf senescence (Rubia et al ) and if so, then detillering could have acted to delay leaf senescence by maintaining higher leaf protein contents. Detillering did not bring about specific increase in the Rubisco contents relative to total leaf soluble proteins in either cultivar.…”

Section: Discussionmentioning

confidence: 99%

Restricting the above ground sink corrects the root/shoot ratio and substantially boosts the yield potential per panicle in field‐grown rice (Oryza sativa L.)

Nada

Abogadallah

2015

Physiologia Plantarum

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Rice has shallow, weak roots, but it is unknown how much increase in yield potential could be achieved if the root/shoot ratio is corrected. Removing all tillers except the main one, in a japonica (Sakha 101) and an indica (IR64) rice cultivar, instantly increased the root/shoot ratio from 0.21 to 1.16 in Sakha 101 and from 0.16 to 1.46 in IR64. Over 30 days after detillering, the root/shoot ratios of the detillered plants decreased to 0.49 in Sakha 101 and 0.46 in IR64 but remained significantly higher than in the controls. The detillered plants showed two- or fourfold increase in the main tiller fresh weight, as a consequence of more positive midday leaf relative water content (RWC), and consistently higher rates of stomatal conductance and photosynthesis, but not transpiration, compared with the controls. The enhanced photosynthesis in Sakha 101 after detillering resulted from both improved water status and higher Rubisco contents whereas in IR64, increasing the Rubisco content did not contribute to improving photosynthesis. Detillering did not increase the carbohydrate contents of leaves but prevented starch depletion at the end of grain filling. The leaf protein content during vegetative and reproductive stages, the grain filling rate, the number of filled grains per panicle were greatly improved, bringing about 38.3 and 35.9% increase in the harvested grain dry weight per panicle in Sakha 101 and IR64, respectively. We provide evidence that improving the root performance by increasing the root/shoot ratio would eliminate the current limitations to photosynthesis and growth in rice.

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“…Recently, Rubia et al (2014) reported that low CK levels were associated with growth inhibition and onset of senescence.…”

Section: Discussionmentioning

confidence: 99%

“…Water stress affects synthesis and/or signaling pathways of hormones and triggers expression of stress-responsive genes, which in turn appear to affect leaf senescence (Shao et al, 2009, Ma et al, 2011. ABA (Wang et al, 2008, Gan, 2010, ethylene (Grbic and Bleecker, 1995), jasmonates (He et al, 2002), and salicylic acid (Morris et al, 2000) promote leaf senescence, whereas CK (Rubia et al, 2014), gibberellins (Mutui et al, 2006) and auxins (Mueller-Roeber and Balazadeh, 2014) delay senescence. Furthermore, carbohydrate accumulation and high carbon-to-low nitrogen ratios are other factors that regulate leaf senescence (Wingler et al, 2006).…”

Section: Water Stress Induces Leaf Senescencementioning

confidence: 99%

“…The level of active CK in particular cell types is the summation of the de novo biosynthesis/degradation and transport into those cells. Thus, optimal level of bioactive CK could promote plant growth and development or greater tolerance to water stress (Pospisilova et al, 2005, Nishiyama et al, 2011, Reguera et al, 2013, Rubia et al, 2014. Application of trans-zeatin (Z), trans-zeatin riboside (ZR), 6-benzyladenine (BA) and other CK to the leaf epidermis can reverse ABA-induced stomatal closure and retard senescence (Pospíšilová, 2003).…”

Section: Cytokinin Application For Enhanced Drought Tolerancementioning

confidence: 99%

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Conditional up-regulation of cytokinin status increases growth and survival of sugarcane in water-limited conditions

Punpee

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Water deficit (water stress) is a major cause of yield loss across all crops. It is the single largest crop productivity constraint in sugarcane in most of sugarcane producing countries and is attracting considerable research interest. Several biological factors have been implicated to water stress responses in plants. Hormones, particularly abscisic acid (ABA), ethylene, cytokinins (CK) and gibberellins are emerging as key regulators of water stress responses. Here, I explored the effect of artificial elevation of CK levels on the response of young sugarcane plants to water stress. Focus of the research was on the onset of senescence and change in photosynthesis that typify water stress responses of plants. Understanding the mechanistic basis of responses of sugarcane to water stress may allow developing strategies for crop improvement and breeding. I studied the effects of modifying cytokinin (CK) levels in water-stressed sugarcane (Saccharum officinarum L.) via two strategies; exogenous supply of synthetic cytokinin N6-benzyladenine (BA) and conditional or constitutional up-regulation of CK biosynthesis in 113 independent transgenic sugarcane lines that were generated as part of this thesis research. Young plants were exposed to water stress in the glasshouse by maintaining soil moisture at 50% field capacity via daily irrigation. Exogenous application of CK occurred via foliar spray or a root drench, while conditional up-regulation of endogenous CK levels under water stress conditions was achieved by expressing the gene encoding CK biosynthesis regulatory enzyme, 2-isopentenyltransferase (IPT), via senescence-associated (SAG12) or abscisic acid-responsive (RAB17) promoters. Maize Ubi promoter was used for constitutive expression of IPT transgene. A popular Australian sugarcane variety Q208A was used for this study. All promotors elevated endogenous CK levels under water stress conditions in the majority of the transgenic lines created. Responses to water stress was studied by quantifying biomass, root/shoot allocation, leaf area, photosynthesis parameters, hormone profiles and gene expression to discern the effects of impaired water relations on carbon fixation and the basis of CKinduced growth improvement. Increased CK levels, via exogenous supply of BA or stress-induced expression of IPT, strongly improved sugarcane growth and survival under water stress. On average, plants with elevated CK-levels retained 30-40% more chlorophyll and 40-50% more green leaf area than wild-type plants at the end of 50 days of growth under water deficit conditions.Compared with control plants, CK-supplied and IPT-transgenic plants maintained higher photosynthetic rates and stomatal conductance, and achieved greater biomass under water stress.External supply of CK significantly increased growth under water stressed and non-stressed ii conditions in wild type plants compared to those that did not receive CK. Transgenic line RAB25showed the greatest improvement in biomass production. Some transgenic lines, including RAB2...

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Changes in the Chlorophyll Content and Cytokinin Levels in the Top Three Leaves of New Plant Type Rice During Grain Filling

Cited by 13 publications

References 57 publications

Application of Salicylic Acid Improves Filling of Inferior Grains of Rice during Late Maturity under Mild Cold Stress

Application of Salicylic Acid Improves Filling of Inferior Grains of Rice during Late Maturity under Mild Cold Stress

Restricting the above ground sink corrects the root/shoot ratio and substantially boosts the yield potential per panicle in field‐grown rice (Oryza sativa L.)

Conditional up-regulation of cytokinin status increases growth and survival of sugarcane in water-limited conditions

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