Stress Physiology: Abiotic Stresses

Lakshmanan, Prakash; Robinson, Nicole

doi:10.1002/9781118771280.ch16

Cited by 42 publications

(56 citation statements)

References 127 publications

(165 reference statements)

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“…Insufficient soil moisture inhibits cell division in the root meristem and results in poor root development, and crop establishment (Lakshmanan and Robinson, 2014). Root growth of sugarcane was substantially inhibited at comparatively mild water deficit (Ψ soil to -0.5 MPa) (Singh and Srivastava, 1974).…”

Section: Water Stress and Sugarcane Root Growthmentioning

confidence: 99%

“…Drought tolerance is one of the priority research areas in major agribusiness companies. As with the broadacre crops, substantial research effort is currently underway in developing drought tolerant sugarcane via transgenic and conventional strategies (Basnayake et al, 2012, Lakshmanan andRobinson, 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Such protracted stress periods cause substantial reduction in photosynthesis, green leaf area and yield. Inhibition of shoot growth, loss of green leaf area and photosynthesis are the most pronounced water stressinduced morphological effects observed in sugarcane Smith, 2005, Lakshmanan andRobinson, 2014). Sugarcane growth is very sensitive to water stress and little is known about hormonal regulation of sugarcane growth and development, especially in relation to water availability.…”

Section: Thesis Objectivementioning

confidence: 99%

“…The net effect of water deficit is largely determined by the dynamics, duration and intensity of soil water depletion, atmospheric water demand, other prevailing environmental stresses, as well as the stage of plant growth and phenology (Grant, 2012). Note that the magnitude of these responses varies greatly between species and varieties within the same crop (Lakshmanan and Robinson, 2014).…”

Section: Plant Responses To Water Stressmentioning

confidence: 99%

“…Stomatal conductance plays a critical role in plant adaptation to water-limited conditions. It has been suggested that stomata may respond to drought-induced changes in hydraulic resistance of xylem and the consequent decreased water and nutrient uptake (Cochard et al, 2002, Lakshmanan andRobinson, 2014).…”

Section: Stomatal Activity and Plant Water Relationsmentioning

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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Section: Water Stress and Sugarcane Root Growthmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Thesis Objectivementioning

confidence: 99%

Section: Plant Responses To Water Stressmentioning

confidence: 99%

Section: Stomatal Activity and Plant Water Relationsmentioning

confidence: 99%

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