Starch-accumulating Sweet Potato Callus Tissue Devoid of<i>β</i>-Amylase but with Two Starch Phosphorylase Isozymes

Wang, Heng-Long; Lee, Ping-Du; Juang, Rong-Huay; Su, Jun-Ming

doi:10.1271/bbb.57.1311

Cited by 9 publications

(7 citation statements)

References 6 publications

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“…However it is comparable to the starch content in the early developmental stages of the grain [ 26 , 27 ]. Similar amounts of starch were also found in potato and sweet potato callus tissue, and in suspension cell cultures of rice [ 9 , 10 , 21 , 23 , 28 ]. As reported above, the actual amount of starch which could be purified from callus was 5 – 10 mg per 1 g dw (0.5–1% w/w), which suggests that more than 75% of the starch is lost during the purification process.…”

Section: Resultssupporting

confidence: 53%

“…However we suggest that it may be possible to optimize culture conditions (e.g. hormones concentration, temperature, carbohydrate concentration) in order to increase starch content, influence the starch biosynthetic activity pathway and alter starch composition [ 9 , 11 , 12 , 21 , 22 ]. This could increase the resemblance among the callus and the endosperm system, increasing the in vitro culture ability to serve as a model system [ 23 ].…”

Section: Resultsmentioning

confidence: 99%

“…Callus tissues of different plants accumulate starch granules especially when they are grown in high sugar media and specific culture conditions, such as controlled temperature, correct hormone treatment and osmotic potential [9-15]. It is not clear why starch is deposited in callus.…”

Section: Introductionmentioning

confidence: 99%

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Barley callus: a model system for bioengineering of starch in cereals

et al. 2012

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BackgroundStarch is the most important source of calories for human nutrition and the majority of it is produced by cereal farming. Starch is also used as a renewable raw material in a range of industrial sectors. It can be chemically modified to introduce new physicochemical properties. In this way starch is adapted to a variety of specific end-uses. Recombinant DNA technologies offers an alternative to starch industrial processing. The plant biosynthetic pathway can be manipulated to design starches with novel structure and improved technological properties. In the future this may reduce or eliminate the economical and environmental costs of industrial modification. Recently, many advances have been achieved to clarify the genetic mechanism that controls starch biosynthesis. Several genes involved in the synthesis and modification of complex carbohydrates in many organisms have been identified and cloned. This knowledge suggests a number of strategies and a series of candidate genes for genetic transformation of crops to generate new types of starch-based polymers. However transformation of cereals is a slow process and there is no easy model system available to test the efficiency of candidate genes in planta.ResultsWe explored the possibility to use transgenic barley callus generated from immature embryo for a fast test of transgenic modification strategies of starch biosynthesis. We found that this callus contains 4% (w/w dw) starch granules, which we could modify by generating fully transgenic calli by Agrobacterium-transformation. A Green Fluorescent Protein reporter protein tag was used to identify and propagate only fully transgenic callus explants. Around 1 – 1.5 g dry weight of fully transgenic callus could be produced in 9 weeks. Callus starch granules were smaller than endosperm starch granules and contained less amylose. Similarly the expression profile of starch biosynthesis genes were slightly different in callus compared with developing endosperm.ConclusionsIn this study we have developed an easy and rapid in planta model system for starch bioengineering in cereals. We suggest that this method can be used as a time-efficient model system for fast screening of candidate genes for the generation of modified starch or new types of carbohydrate polymers.

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Section: Resultssupporting

confidence: 53%

Section: Resultsmentioning

confidence: 99%

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Barley callus: a model system for bioengineering of starch in cereals

et al. 2012

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“…The typical pattern of fluctuations in starch phosphorylase activity showed minor differences in the level of activity between days 18 and 22, but it was not so strong as to justify the delayed starch degradation. Wang et al (1993) observed the presence of two new starch phosphorylase isoforms in callus tissue of sweet potato growing in a medium without auxin. The western-blot analysis did not indicate any appreciable difference between the profiles of phosphorylase protein of control and treated slices.…”

Section: Discussionmentioning

confidence: 95%

Activity and expression of banana starch phosphorylases during fruit development and ripening

Mota

Cordenunsi

Nascimento

et al. 2002

Planta

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Two main forms of starch phosphorylase (EC 2.4.1.1) were identified and purified from banana (Musa acuminata Colla. cv. Nanicão) fruit. One of them, designated phosphorylase I, had a native molecular weight of 155 kDa and subunit of 90 kDa, a high affinity towards branched glucans and an isoelectric point around 5.0. The other, phosphorylase II, eluted at a higher salt concentration from the anion exchanger, had a low affinity towards branched glucans, a native molecular weight of 290 kDa and subunit of 112 kDa. Kinetic studies showed that both forms had typical hyperbolic curves for orthophosphate (Pi) and glucose-1-phosphate, and that they could not react with substrates with a blocked reducing end or alpha-1,6 glucosidic bonds. Antibodies prepared against the purified type-II form and cross-reacting with the type-I form showed that there was an increase in protein content during development and ripening of the fruit. The changes in protein level were parallel to those of phosphorylase activity, in both the phosphorolytic and synthetic directions. Considering the kinetics, indicating that starch phosphorylases are not under allosteric control, it can be argued that protein synthesis makes a contribution to regulating phosphorylase activity in banana fruit and that hormones, like gibberellic acid and indole-3-acetic acid, may play a regulating role. For the first time, starch phosphorylases isoforms were detected as starch-granule-associated proteins by immunostaining of SDS-PAGE gels.

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“…Determined by the Fiske Subbarow method after HClO4 incineration of defatted starch 3. Determined using a Coulter LS130 4. Determined using a Rigaku RU 200B X ray diffractometer.…”

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confidence: 99%

Study on Organ-specific Starch Properties of Sweetpotato

Kitahara

2005

J. Appl. Glycosci.

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To study starch biosynthesis in terms of molecular structures of organ-specific starches within one plant species is interesting. The structural properties of starches from tuberous roots of various sweetpotato varieties and breeding lines, and also starches from leaf and callus of sweetpotato cv. Koganesengan were investigated in this study. Examination of the structure and pasting properties of the 16 kinds of root starches suggested that, statistically, the variation in pasting properties of the starches was more accurately reflected by amylopectin structures than by amylose. During the course of examination on starch structures of the latest breeding lines, we found two lines having root starches with unique characteristics. One had low amylose starch and the other had low temperature gelatinizing starch. The physicochemical properties of these starches were likewise characterized. In leaves where the starch structures and their diurnal-nocturnal changes were examined from leaves harvested at different times of a day. Gel-permeation chromatography of the leaf starches and amylopectins showed that, compared to root starch, the leaf starches had higher amount of materials eluted at the low molecular weight fraction which contained both amylose and a large amount of small amylopectin molecules. It was found that the amylose content of the leaf starches dropped during the daytime whereas the branch aspect of the leaf amylopectins remained relatively constant throughout the whole day. Finally, the structural properties of starch formed in the sweetpotato callus were studied. The starch content increased from nearly zero to the maximum content in the first week of culture, and then decreased afterward. Based on the chain-length distributions of the callus starches at different culture periods, it was demonstrated that the structural change from waxy to normal feature of starch granule occurred during the culture of the callus. Thus, the structural characteristics of starches from tuberous root, leaf and callus of sweetpotato have been revealed.

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Starch-accumulating Sweet Potato Callus Tissue Devoid ofβ-Amylase but with Two Starch Phosphorylase Isozymes

Cited by 9 publications

References 6 publications

Barley callus: a model system for bioengineering of starch in cereals

Barley callus: a model system for bioengineering of starch in cereals

Activity and expression of banana starch phosphorylases during fruit development and ripening

Study on Organ-specific Starch Properties of Sweetpotato

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