Genotypic variations in activities of phosphoenolpyruvate carboxylase and correlations with leaf photosynthetic characteristics and crop productivity of cassava grown in low-land seasonally-dry tropics

El‐Sharkawy, Mabrouk A.; Lopez, Y.; Bernal, L. M.

doi:10.1007/s11099-008-0038-4

Cited by 20 publications

(28 citation statements)

References 47 publications

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“…Leaf photosynthetic rates of various cassava varieties subjected to water stress in the field were significantly and positively correlated with the activity of the C 4 enzyme PEPC activity in extracts of the same measured leaves (El-Sharkawy, 2004). Table 5 (El-Sharkawy et al, 2008) presents correlation coefficients and regressions between yield, photosynthetic characteristics, and PEPC activity in 18 varieties selected from the preliminary trial in Patia. There were significant correlations between yield, photosynthetic characteristics and PEPC activity.…”

Section: Evaluation Of Core Germplasm For Productivity and Photosynthmentioning

confidence: 99%

“…Two areas of research and development need to be addressed on the potential use of cassava as a mainstay crop tolerant to extreme water deficits and to marginal lands in the tropics and subtropics where severe drought prevails and shortages of food and feed are chronic, particularly in Sub-Saharan Africa: (1) Through the use of modern molecular biology tools, more basic research on cassava biochemical photosynthetic characterization should be done to search for genetic diversity within cultivated cassava and wild Manihot species in order to identify genetic sources with high photosynthetic rates and enhanced activities of key photosynthetic enzymes, focusing on PEPC and C 3 -C 4 traits (El-Sharkawy and de Tafur, 2007;El-Sharkawy et al, 2008). The use of molecular markers and marker assisted selection should facilitate and enhance the conventional breeding process for drought-tolerance in cassava (Setter and Fregene, 2007).…”

Section: Future Workmentioning

confidence: 99%

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Physiological characteristics of cassava tolerance to prolonged drought in the tropics: implications for breeding cultivars adapted to seasonally dry and semiarid environments

El‐Sharkawy

2007

Braz. J. Plant Physiol.

126

114

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The paper summarizes research conducted at International Center for Tropical Agriculture (CIAT) on responses of cassava to extended water shortages in the field aided by modern gas-exchange and water-relation techniques as well as biochemical assays. The aim of the research was to coordinate basic and applied aspects of crop physiology into a breeding strategy with a multidisciplinary approach. Several physiological characteristics/traits and mechanisms underpinning tolerance of cassava to drought were elucidated using a large number of genotypes from the CIAT core germplasm collection grown in various locations representing ecozones where cassava is cultivated. Most notable among these characteristics are the high photosynthetic capacity of cassava leaves in favorable environments and the maintenance of reasonable rates throughout prolonged water deficits, a crucial characteristic for high and sustainable productivity. Cassava possess a tight stomatal control over leaf gas exchange that reduces water losses when plants are subjected to soil water deficits as well as to high atmospheric evaporative demands, thus protecting leaves from severe dehydration. During prolonged water deficits, cassava reduces its canopy by shedding older leaves and forming smaller new leaves leading to less light interception, another adaptive trait to drought. Though root yield is reduced (but much less than the reduction in top growth) under water stress, the crop can recover when water becomes available by rapidly forming new canopy leaves with much higher photosynthetic rates compared to unstressed crops, thus compensating for yield losses with final yields approaching those in well-watered crops. Cassava can extract slowly water from deep soils, a characteristic of paramount importance in seasonally dry and semiarid environments where deeply stored water needs to be tapped. Screening large accessions under seasonally dry and semiarid environments showed that yield is significantly correlated with upper canopy leaf photosynthetic rates, and the association was attributed mainly to nonstomatal (anatomical/biochemical) factors. Parental materials with both high yields and photosynthetic rates were identified for incorporation into breeding and selection programs for cultivars adapted to prolonged drought coupled with high temperatures and dry air, conditions that might be further aggravated by global climate changes in tropical regions. Key words: agriculture, breeding, canopy, carboxylation enzymes, C 3 -C 4 intermediate, ecophysiology, growth, leaf photosynthesis, Manihot sp., PEP carboxylase, productivity, stomata, water stress, yield Características fisiológicas da tolerância da mandioca a secas prolongadas nos trópicos: Implicações para o melhoramento de cultivares adaptadas a ambientes semi-áridos e sazonalmente secos: Este artigo sumaria resultados de pesquisas conduzidas no Centro Internacional para Agricultura Tropical (CIAT), sobre as respostas da mandioca a períodos prolongados de déficit hídrico, no campo, centrando-se em...

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Section: Evaluation Of Core Germplasm For Productivity and Photosynthmentioning

confidence: 99%

Section: Future Workmentioning

confidence: 99%

Physiological characteristics of cassava tolerance to prolonged drought in the tropics: implications for breeding cultivars adapted to seasonally dry and semiarid environments

El‐Sharkawy

2007

Braz. J. Plant Physiol.

126

114

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“…The high PNUE may confer an adaptive advantage and a high level of competitivness for the C 4 species in lowfertility soils. However, in C 3 -C 4 intermediate cassava, yield was positively correlated with PNUE across a large group of genotypes grown under rainfed field conditions (El-Sharkawy 2004, 2007, El-Sharkawy et al 2008. This finding may explain why cassava has a high level of adaptability to low-nitrogen soils (CIAT 1986, Howeler 2002, Howeler and Cadavid 1990, Pellet and ElSharkawy 1993a,b, 1997.…”

Section: Comparative Productivity and Plant-water Relations In C 4 Anmentioning

confidence: 96%

“…Thus, high PNUE in cassava apparently confers an adaptive advantage in low-nitrogen soils and points to the importance of selection for higher photosynthetic rates in breeding programes in order to maximize nutrient, as well as water, use efficiency. Cassava PEPC activity was in leaf extracts found to be 10-30 % of levels observed in C 4 species such as maize and sorghum with significant differences among genotypes under field conditions in different environments (El-Sharkawy and Cock 1990, ElSharkawy 2004, 2006b, 2007, El-Sharkawy et. al.…”

Section: Comparative Productivity and Plant-water Relations In C 4 Anmentioning

confidence: 97%

Pioneering research on C<sub>4</sub> leaf anatomical, physiological, and agronomic characteristics of tropical monocot and dicot plant species: Implications for crop water relations and productivity in comparison to C<sub>3</sub> cropping systems

El‐Sharkawy¹

2009

Photosynt.

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The review is done to summarise the history of the discoveries of the many anatomical, agronomical, and physiological aspects of C 4 photosynthesis (where the first chemical products of CO 2 fixation in illuminated leaves are four-carbon dicarboxylic acids) and to document correctly the scientists at the University of Arizona and the University of California, Davis, who made these early discoveries. The findings were milestones in plant science that occurred shortly after the biochemical pathway of C 3 photosynthesis in green algae (where the first chemical product is a three-carbon compound) was elucidated at the University of California, Berkeley, and earned a Nobel Prize in chemistry. These remarkable achievements were the result of ground-breaking pioneering research efforts carried out by many agronomists, plant physiologists and biochemists in several laboratories, particularly in the USA. Numerous reviews and books written in the past four decades on the history of C 4 photosynthesis have focused on the biochemical aspects and give an unbalanced history of the multidisciplinary/multinstitutional nature of the achievements made by agronomists, who published much of their work in Crop Science. Most notable among the characteristics of the C 4 species that differentiated them from the C 3 ones are: (I) high optimum temperature and high irradiance saturation for maximum leaf photosynthetic rates; (II) apparent lack of CO 2 release in a rapid stream of CO 2 -free air in illuminated leaves in varying temperatures and high irradiances; (III) a very low CO 2 compensation point; (IV) lower mesophyll resistances to CO 2 diffusion coupled with higher stomatal resistances, and, hence, higher instantaneous leaf water use efficiency; (V) the existence of the so-called "Kranz leaf anatomy" and the higher internal exposed mesophyll surface area per cell volume; and (VI) the ability to recycle respiratory CO 2 by illuminated leaves. PhD in crop physiology, The University of Arizona, Tucson, 1965]. For more than four decades, he has contributed to research in field crop production, breeding, and physiology of cotton, cereal crops and the root tropical crop cassava. He took a leading role in establishing a faculty of agriculture, Tripoli University, Libyan Arab Republic, and participated in the pioneering agricultural development projects under irrigation in the semiarid and arid ecosystems of North Africa and the Sahara. Abbreviations: C i − intercellular CO 2 concentration; DM − dry mass; NAD-ME − NAD-dependent malic enzyme; NADP-ME − NADP-dependent malic enzyme; PAR − photosynthetically active radiation; PCK − phosphoenolpyruvate carboxykinase; PCRC − photosynthetic carbon reduction cycle − PEPC − phosphoenolpyruvate carboxylase; PGA − 3-phosphoglycerate; PNUE − photosynthetic nitrogen use efficiency; PPDK − pyruvate orthophosphate dikinase; P N − leaf net photosynthetic rate; r m − mesophyll resistances to CO 2 diffusion; r k − intracellular resistances to CO 2 diffusion; Rubisco − ribulose-1,5-bisphosphate carboxylase/ ...

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“…Brazil is considered the possible center of origin for this species (Allem, 1994), which is one of the most important crop in the tropics and the basic food for over 800 million people (Nassar et al, 2009), being cultivated on 16 million hectares worldwide (El-Sharkawy et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Physiological and agronomic characteristics of cassava genotypes

Guimarães¹,

Prates²,

Viana³

et al. 2017

Afr. J. Agric. Res.

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Genotypic variations in activities of phosphoenolpyruvate carboxylase and correlations with leaf photosynthetic characteristics and crop productivity of cassava grown in low-land seasonally-dry tropics

Cited by 20 publications

References 47 publications

Physiological characteristics of cassava tolerance to prolonged drought in the tropics: implications for breeding cultivars adapted to seasonally dry and semiarid environments

Physiological characteristics of cassava tolerance to prolonged drought in the tropics: implications for breeding cultivars adapted to seasonally dry and semiarid environments

Pioneering research on C<sub>4</sub> leaf anatomical, physiological, and agronomic characteristics of tropical monocot and dicot plant species: Implications for crop water relations and productivity in comparison to C<sub>3</sub> cropping systems

Physiological and agronomic characteristics of cassava genotypes

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