Predominantly symplastic phloem unloading of photosynthates maintains efficient starch accumulation in the cassava storage roots (Manihot esculenta Crantz)

Abstract Background Cassava (Manihot esculenta Crantz) efficiently accumulates starch in its storage roots. However, how photosynthates are transported from the leaves to the phloem (especially how they are unloaded into parenchymal cells of storage roots) remains unclear. Results Here, we investigated the sucrose unloading pattern and its impact on cassava storage root development using microstructural and physiological analyses, namely, carboxyfluorescein (CF) and C14 isotope tracing. The expression profiling of genes involved in symplastic and apoplastic transport was performed, which included enzyme activity, protein gel blot analysis, and transcriptome sequencing analyses. These finding showed that carbohydrates are transported mainly in the form of sucrose, and more than 54.6% was present in the stem phloem. Sucrose was predominantly unloaded symplastically from the phloem into storage roots; in addition, there was a shift from apoplastic to symplastic unloading accompanied by the onset of root swelling. Statistical data on the microstructures indicated an enrichment of plasmodesmata within sieve, companion, and parenchyma cells in the developing storage roots of a cultivar but not in a wild ancestor. Tracing tests with CF verified the existence of a symplastic channel, and [14C] Suc demonstrated that sucrose could rapidly diffuse into root parenchyma cells from phloem cells. The relatively high expression of genes encoding sucrose synthase and associated proteins appeared in the middle and late stages of storage roots but not in primary fibrous roots, or secondary fibrous roots. The inverse expression pattern of sucrose transporters, cell wall acid invertase, and soluble acid invertase in these corresponding organs supported the presence of a symplastic sucrose unloading pathway. The transcription profile of genes involved in symplastic unloading and their significantly positive correlation with the starch yield at the population level confirmed that symplastic sucrose transport is vitally important in the development of cassava storage roots. Conclusions In this study, we revealed that the cassava storage root phloem sucrose unloading pattern was predominantly a symplastic unloading pattern. This pattern is essential for efficient starch accumulation in high-yielding varieties compared with low-yielding wild ancestors.

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Predominantly symplastic phloem unloading of photosynthates maintains efficient starch accumulation in the cassava storage roots (Manihot esculenta Crantz)

10.21203/rs.3.rs-48370/v2 ◽

2020 ◽

Author(s):

Kun Pan ◽

Cheng Lu ◽

Peixian Nie ◽

Meizhen Hu ◽

Xincheng Zhou ◽

...

Keyword(s):

Manihot Esculenta ◽

Early Stage ◽

Population Level ◽

Starch Accumulation ◽

Storage Roots ◽

Sucrose Transport ◽

Phloem Unloading ◽

Manihot Esculenta Crantz ◽

Parenchyma Cells ◽

Fibrous Roots

Abstract Background: It is well known that cassava (Manihot esculenta Crantz) highly efficiently accumulates starch in its storage roots, but how photosynthates are transported from the leaves to the phloem (especially how they are unloaded into parenchymal cells of storage roots) remains unclear. Methods: Here, we investigated the phloem unloading pattern of sucrose and its impact on the development of cassava storage roots through microstructural and physiological analyses and carboxyfluorescein (CF) and isotope C14 tracing. Expression profiling of genes involved in symplastic and apoplastic transport was performed, and their correlations with storage root yield were determined in populations according to enzyme activity, Western blotting analysis and transcriptome sequencing. Results: Carbohydrates are transported mainly in the form of sucrose, with more than 54.6% present in the stem phloem at any time. Sucrose was predominantly unloaded symplastically from the phloem into storage roots, but there was a shift from apoplastic to symplastic unloading accompanied by the onset of root swelling. Statistical data concerning the microstructure revealed an enrichment of plasmodesmata within sieve, companion and parenchyma cells in the developing storage roots of a cultivar but not in a wild ancestor. Tracing tests with CF verified the existence of a coplastid channel, and [14C]Suc demonstrated that the marked sucrose could rapidly diffuse into root parenchyma cells from phloem cells. The relatively high expression of genes encoding SuSy and associated proteins in the storage roots at the middle and late stages but not in the early stage of storage roots, primary fibrous roots or secondary fibrous roots and the inverse expression pattern of SUTs, CWI and SAI in these corresponding organs supported the presence of a symplastic sucrose unloading pathway. The transcriptome pattern of genes involved in symplastic unloading and their significantly positive correction with starch yield at the population level confirmed that symplastic sucrose transport is vitally important in the development of cassava storage roots. Conclusions: In this study, we revealed a predominantly symplastic phloem unloading pattern of sucrose in cassava storage roots. This pattern is essential for the efficient starch accumulation for sucrose transport between high-yielding varieties and low-yielding wild ancestors.

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Predominantly symplastic phloem unloading of photosynthates maintains efficient starch accumulation in the cassava storage roots (Manihot esculenta Crantz)

10.21203/rs.3.rs-48370/v3 ◽

2020 ◽

Author(s):

Kun Pan ◽

Cheng Lu ◽

Peixian Nie ◽

Meizhen Hu ◽

Xincheng Zhou ◽

...

Keyword(s):

Manihot Esculenta ◽

Early Stage ◽

Population Level ◽

Starch Accumulation ◽

Storage Roots ◽

Sucrose Transport ◽

Phloem Unloading ◽

Manihot Esculenta Crantz ◽

Parenchyma Cells ◽

Fibrous Roots

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Photosynthates Predominantly Symplasmic Phloem Unloading Maintained the Efficient Biomass Accumulation in Storage Root of Cassava (Manihot Esculenta Crantz)

10.21203/rs.3.rs-48370/v1 ◽

2020 ◽

Author(s):

Kun Pan ◽

Cheng Lu ◽

Peixian Nie ◽

Meizhen Hu ◽

Xincheng Zhou ◽

...

Keyword(s):

Manihot Esculenta ◽

Parenchymal Cell ◽

Starch Accumulation ◽

Storage Root ◽

Fibrous Root ◽

Phloem Unloading ◽

Manihot Esculenta Crantz ◽

Wild Ancestor ◽

High Efficient ◽

Parenchyma Cells

Abstract Background: It is well known that cassava (Manihot esculenta Crantz) high efficient accumulates starch in its storage root underground, but how the photosynthates transported from leaves to the phloem, especially unloaded into the parenchymal cell of storage root remains unclear.Methods: Here, we investigated the phloem unloading pattern of sucrose and its impact to the development of storage root in cassava through microstructural and physiological analyses, trace of carboxyfluorescein (CF) and Isotope C14. Identification of expression profiling of the genes involved in symplasmic and apoplasmic transport and their correlation with storage root yield in population by enzymatic activity, western blotting analysis and Transcriptome Sequencing.Results: The carbohydrates are transported mainly as form of sucrose with above 54.6% measured with stem phloem instantly. The sucrose was predominantly symplasmic unloading from phloem into storage root, but there was a shift from apoplasmic to symplasmic unloading accompanied by the onset of root swelling. Microstructure statistics revealed the plasmodesmata enriched among sieve, companion and parenchyma cells in the developing storage root of cultivated variety but not in a wild ancestor. Tracing test with CF verified exist of coplastid channel and [14C]Suc demonstrated that the sucrose marked could rapid diffusion into root parenchyma cells from phloem cells. The higher expression of genes and proteins for SuSys in storage root at middle and late stage but not in early stage of storage root, primary fibrous root and second fibrous root, and the inversely expressed pattern of SUTs, CWI and SAI in these corresponding organs supported that there are a symplasmic sucrose unloading pathway. The transcriptomic pattern of genes involved in symplasmic unloading and their significantly positive correction with starch yielding in population level confirmed it is vital important that the symplasmic sucrose transport in developing storage root of cassava. Conclusions: In the study, we uncovered a predominantly symplasmic phloem unloading pattern of sucrose in the storage root of cassava. And this advantage is essential to efficient starch accumulation for sucrose transports between a high yield variety to low yield wild ancestor.

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Studies toward the identification of transcription factors in cassava storage root

Brazilian Journal of Plant Physiology ◽

10.1590/s1677-04202003000300006 ◽

2003 ◽

Vol 15 (3) ◽

pp. 167-170 ◽

Cited By ~ 2

Author(s):

Cláudia Regina Batista de Souza ◽

Elionor Rita Pereira de Almeida ◽

Luiz Joaquim Castelo Branco Carvalho ◽

Eugen Silvano Gander

Keyword(s):

Transcription Factor ◽

Transcription Factors ◽

Manihot Esculenta ◽

Plant Traits ◽

Storage Root ◽

Brazil Nut ◽

Manihot Esculenta Crantz ◽

Physiological Processes ◽

Cassava Storage Root

Transcription factors play important roles in several physiological processes. In recent years many transcription factors have been isolated from plants and they are emerging as powerful tools in the manipulation of plant traits. In this work we initiated studies in order to isolate transcription factors from cassava (Manihot esculenta Crantz), an important tropical and subtropical crop. Our results show three kinds of proteins expressed differentially in cassava storage root and immunologically related to the opaque-2 transcription factor from maize. Southwestern experiments showed two proteins capable of interacting in vitro with the DNA sequence of the be2S1 gene from the Brazil nut tree.

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RNAi inhibition of feruloyl CoA 6′-hydroxylase reduces scopoletin biosynthesis and post-harvest physiological deterioration in cassava (Manihot esculenta Crantz) storage roots

Plant Molecular Biology ◽

10.1007/s11103-017-0602-z ◽

2017 ◽

Vol 94 (1-2) ◽

pp. 185-195 ◽

Cited By ~ 10

Author(s):

Shi Liu ◽

Ima M. Zainuddin ◽

Herve Vanderschuren ◽

James Doughty ◽

John R. Beeching

Keyword(s):

Manihot Esculenta ◽

Storage Roots ◽

Manihot Esculenta Crantz ◽

Post Harvest

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Effect of Photoperiod on Growth and Development of Cassava (Manihot esculenta Crantz)

Functional Plant Biology ◽

10.1071/pp9850621 ◽

1985 ◽

Vol 12 (6) ◽

pp. 621 ◽

Cited By ~ 6

Author(s):

BA Keating ◽

GL Wilson ◽

JP Evenson

Keyword(s):

Growth Rate ◽

Relative Growth Rate ◽

Growth And Development ◽

Day Treatment ◽

Storage Root ◽

Storage Roots ◽

Manihot Esculenta Crantz ◽

Dry Matter Partitioning ◽

Relative Growth ◽

Controlled Environments

Effects of photoperiod on growth and development of cassava were studied in controlled environments. Plants of cultivars M Aus 7 and M Aus 10 were grown under short (10-h) and long (16-h) photoperiods and harvested at approximately weekly intervals for a period of 13 weeks. Long photoperiods resulted in large increases in leaf area through increases in both number (both cultivars) and size of leaves (M Aus 7 only). The timing, extent and anatomical characteristics of storage root initiation were similar for both cultivars under 10-h and 16-h photoperiods but the subsequent balance between shoot and storage root growth strongly favoured shoot growth in long days. Dry matter partitioning followed a simple allometric pattern with the proportionality between the relative growth rate of shoots and the relative growth rate of storage roots remaining constant with time but being altered by photoperiod. Distribution to storage roots was quantitatively reduced in another experiment using M Aus 10 with each additional 1-h increment from 10-h to 16-h photoperiods. A treatment consisting of a short day (10 h) plus a 1-h night break in the middle of the dark period produced growth similar to long day treatment. Differences in cultivar response (Ceiba, CMC 84 and M Aus 7) to a range of photoperiods (11, 12, 13 and 14 h) were detected in a third experiment. The possible mechanisms and significance of these responses are discussed.

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Evaluation of Morphological Characters and Yield Variability of Some Elite Cassava (Manihot Esculenta Crantz) in Uyo, Southeastern Nigeria

American Journal of Agricultural Science, Engineering and Technology ◽

10.54536/ajaset.v5i2.77 ◽

2021 ◽

Vol 5 (2) ◽

pp. 102-112

Author(s):

Patrick Ibang Udounang ◽

Okon John Ekwere ◽

Ofonime Raphael Akata

Keyword(s):

Block Design ◽

Morphological Characters ◽

Growth And Yield ◽

Yield Variability ◽

Storage Root ◽

Storage Roots ◽

Manihot Esculenta Crantz ◽

Southeastern Nigeria ◽

Significant Difference ◽

Cassava Varieties

Field experiment was carried out at Uyo to evaluate some morphological traits and yield variability of some elite cassava varieties with aim of making innovative recommendation to farmers. The experiment laid out in a complete block design, replicated three times. The treatments were six cassava varieties; TMS 30572, TME 419, TMS 98/0505, TMS 98/0581, TMS 01/1412 and local variety known as Obubit Okpo. Data collected from growth and yield was subjected to analysis of variances. Significant means were compares using least significant difference (LSD) at 5% probability level. Among the cassava varieties; TMS 98/0581 had superiority over in four characters namely; leaf area, storage root length, storage root circumference and yield. Also TMS 01/1412 was superior in terms of number of leaves per plant and number of storage roots per plant while TME 419 was superior in terms of plant height. Since TMS 98/0581 had four major characters, it could be disseminated to farmers in Uyo, Akwa Ibom State, while the other varieties TMS 01/1412, and TME 419 which were superior in two and one characters respectively could be incorporated into breeding programme with TMS 98/0581 to produce hybrid varieties with higher yield for the study area. Keywords: Cassava, characters, breeding and yield.

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