scholarly journals Proximal and Distal Parts of Sweetpotato Adventitious Roots Display Differences in Root Architecture, Lignin, and Starch Metabolism and Their Developmental Fates

2021 ◽  
Vol 11 ◽  
Author(s):  
Vikram Singh ◽  
Hanita Zemach ◽  
Sara Shabtai ◽  
Roni Aloni ◽  
Jun Yang ◽  
...  
Keyword(s):  
Adventitious Roots ◽  
Distal Part ◽  
Root Formation ◽  
Proximal Part ◽  
Starch Biosynthesis ◽  
Fiber Formation ◽  
Starch Accumulation ◽  
Storage Root ◽  
Storage Roots ◽  
Root Part

Sweetpotato is an important food crop globally, serving as a rich source of carbohydrates, vitamins, fiber, and micronutrients. Sweetpotato yield depends on the modification of adventitious roots into storage roots. The underlying mechanism of this developmental switch is not fully understood. Interestingly, storage-root formation is manifested by formation of starch-accumulating parenchyma cells and bulking of the distal part of the root, while the proximal part does not show bulking. This system, where two parts of the same adventitious root display different developmental fates, was used by us in order to better characterize the anatomical, physiological, and molecular mechanisms involved in sweetpotato storage-root formation. We show that, as early as 1 and 2 weeks after planting, the proximal part of the root exhibited enhanced xylem development together with increased/massive lignin deposition, while, at the same time, the distal root part exhibited significantly elevated starch accumulation. In accordance with these developmental differences, the proximal root part exhibited up-regulated transcript levels of sweetpotato orthologs of Arabidopsis vascular-development regulators and key genes of lignin biosynthesis, while the distal part showed up-regulation of genes encoding enzymes of starch biosynthesis. All these recorded differences between proximal and distal root parts were further enhanced at 5 weeks after planting, when storage roots were formed at the distal part. Our results point to down-regulation of fiber formation and lignification, together with up-regulation of starch biosynthesis, as the main events underlying storage-root formation, marking/highlighting several genes as potential regulators, providing a valuable database of genes for further research.

scholarly journals Molecular and Anatomical Characterization of Sweetpotato Storage Root Formation

2011 ◽  
Author(s):  
Don LaBonte ◽  
Etan Pressman ◽  
Nurit Firon ◽  
Arthur Villordon
Keyword(s):  
Root Development ◽  
Adventitious Roots ◽  
Water Deprivation ◽  
Root Formation ◽  
Starch Accumulation ◽  
Root Initiation ◽  
Root Number ◽  
Storage Root ◽  
Storage Root Development

Original objectives: Anatomical study of storage root initiation and formation. Induction of storage root formation. Isolation and characterization of genes involved in storage root formation. During the normal course of storage root development. Following stress-induced storage root formation.   Background:Sweetpotato is a high value vegetable crop in Israel and the U.S. and acreage is expanding in both countries and the research herein represents an important backstop to improving quality, consistency, and yield. This research has two broad objectives, both relating to sweetpotato storage root formation. The first objective is to understand storage root inductive conditions and describe the anatomical and physiological stages of storage root development. Sweetpotato is propagated through vine cuttings. These vine cuttings form adventitious roots, from pre-formed primordiae, at each node underground and it is these small adventitious roots which serve as initials for storage and fibrous (non-storage) “feeder” roots. What perplexes producers is the tremendous variability in storage roots produced from plant to plant. The marketable root number may vary from none to five per plant. What has intrigued us is the dearth of research on sweetpotato during the early growth period which we hypothesize has a tremendous impact on ultimate consistency and yield. The second objective is to identify genes that change the root physiology towards either a fleshy storage root or a fibrous “feeder” root. Understanding which genes affect the ultimate outcome is central to our research. Major conclusions: For objective one, we have determined that the majority of adventitious roots that are initiated within 5-7 days after transplanting possess the anatomical features associated with storage root initiation and account for 86 % of storage root count at 65 days after transplanting. These data underscore the importance of optimizing the growing environment during the critical storage root initiation period. Water deprivation during this phenological stage led to substantial reduction in storage root number and yield as determined through growth chamber, greenhouse, and field experiments. Morphological characterization of adventitious roots showed adjustments in root system architecture, expressed as lateral root count and density, in response to water deprivation. For objective two, we generated a transcriptome of storage and lignified (non-storage) adventitious roots. This transcriptome database consists of 55,296 contigs and contains data as regards to differential expression between initiating and lignified adventitious roots. The molecular data provide evidence that a key regulatory mechanism in storage root initiation involves the switch between lignin biosynthesis and cell division and starch accumulation. We extended this research to identify genes upregulated in adventitious roots under drought stress. A subset of these genes was expressed in salt stressed plants.

scholarly journals Physiological and Anatomical Characterization of a Late-storage Root-forming Mutant of Sweetpotato

2002 ◽  
Vol 127 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Makoto Nakatani ◽  
Masaru Tanaka ◽  
Masaru Yoshinaga
Keyword(s):  
Cross Sections ◽  
Ipomoea Batatas ◽  
Root Formation ◽  
Morphological Characteristics ◽  
Zeatin Riboside ◽  
Storage Root ◽  
Storage Roots ◽  
Physiological Mechanisms ◽  
Maximum Root

A late-storage root-forming mutant (`KM95-A68') of sweetpotato [Ipomoea batatas (L.) Poir.] was characterized to clarify the genetic and physiological mechanisms of storage root formation. This mutant originated from a somaclonal mutation of `Kokei No. 14'. Storage roots of `KM95-A68' are rare and, when formed, develop 2 or 3 weeks later than those of `Kokei No. 14' from which it originated. Morphological characteristics of the canopy and leaf photosynthetic rates of `KM95-A68' were similar to those of `Kokei No. 14'. No apparent differences were observed in the anatomy of root cross sections of `KM95-A68' and `Kokei No. 14'. An apparent increase in the root zeatin riboside (ZR) levels were observed in `Kokei No. 14' at storage root formation. Root ZR levels differed between `Kokei No. 14' and `KM95-A68'. The onset of increase in root ZR levels was delayed by 2 or 3 weeks in `KM95-A68' in comparison to `Kokei No. 14'. Maximum root ZR levels in `Kokei No. 14' were 2.2 times higher in comparison to `KM95-A68'. This appeared to be a factor in delayed storage root formation of `KM95-A68'. Results of reciprocal grafts of `KM95-A68' and `Kokei No. 14' indicated that the late storage root-forming characteristic of `KM95-A68' is a characteristic that arises from the root itself.

scholarly journals Characterization of Adventitious Root Development in Sweetpotato

HortScience ◽  
2009 ◽  
Vol 44 (3) ◽  
pp. 651-655 ◽  
Author(s):  
Arthur Q. Villordon ◽  
Don R. La Bonte ◽  
Nurit Firon ◽  
Yanir Kfir ◽  
Etan Pressman ◽  
...  
Keyword(s):  
Root Development ◽  
Adventitious Root ◽  
Adventitious Roots ◽  
Vascular Cambium ◽  
Storage Root ◽  
Storage Roots ◽  
Adventitious Root Development ◽  
Xylem Elements ◽  
Storage Root Development

Adventitious roots of ‘Beauregard’ and ‘Georgia Jet’ sweetpotato were observed and anatomically characterized over a period of 60 days of storage root development. The majority of ‘Beauregard’ and ‘Georgia Jet’ adventitious roots sampled at 5 to 7 days after transplanting (DAT) possessed anatomical features (five or more protoxylem elements) associated with storage root development. The majority of ‘Beauregard’ (86%) and ‘Georgia Jet’ (89%) storage roots sampled at 60 to 65 DAT were traced directly to adventitious roots extant at 5 to 7 DAT. The two varieties, however, differed in the timing in which regular and anomalous cambia were formed. Regular vascular cambium development, i.e., initiation and completion, was observed in both varieties at 19 to 21 DAT. Formation of complete regular vascular cambium was negligible for ‘Beauregard’ (4%) in comparison with ‘Georgia Jet’ (32%) at 26 to 28 DAT. However, anomalous cambia development adjacent to xylem elements was greater in ‘Beauregard’ (30%) in comparison with ‘Georgia Jet’ (13%). Nearly 40% to 50% of samples in both varieties showed extensive lignification in the stele region. At 32 to 35 DAT, 62% to 70% of the adventitious roots for both varieties had either been initiated (developed anomalous cambium) or were lignified. The remaining adventitious roots showed intermediate stages of vascular cambium development. The adventitious root count increased up to 19 to 21 DAT and then remained constant up to 32 to 35 DAT. These accumulated results suggest that the initial stages of adventitious root development are critical in determining storage root set in sweetpotato.

scholarly journals Split Application under Reduced Nitrogen Rate Favors High Yield by Altering Endogenous Hormones and C/N Ratio in Sweet Potato

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1243
Author(s):  
Xiangbei Du ◽  
Xinyue Zhang ◽  
Lingcong Kong ◽  
Min Xi
Keyword(s):  
Sweet Potato ◽  
Root Formation ◽  
Management Strategies ◽  
Root Weight ◽  
Storage Root ◽  
Split Application ◽  
Storage Roots ◽  
N Content ◽  
N Management ◽  
Aba Content

A process for reducing the nitrogen (N) application rate while maintaining sweet potato yield urgently needs to be determined. A two-year pot experiment was conducted with three N management strategies to explore the mechanism underlying yield increase caused by a split application under a reduced N rate through an investigation of the changes in the carbon (C)-N metabolism and endogenous hormone. Results revealed that, compared with conventional basal N management, split application under a reduced N rate increased storage root yield by 22.1% through improving the storage root number and mean storage root weight by 12.3% and 10.2%, respectively. During the storage root formation period, split application under a reduced N rate decreased the soil-available N (AV-N) content and N content in storage root, inducing elevated C content, C/N ratio, auxin (IAA) content, zeatin and zeatin riboside (Z + ZR) content and reduced abscisic acid (ABA) content in storage roots, promoting storage root formation. During the storage root bulking period, split application under a reduced N rate appropriately elevated the soil AV-N content and N content in the storage root which, together with increased ABA content, which enhanced C content and C/N ratio in the storage root, resulted in an improved mean storage root weight. These results will facilitate the generation of appropriate N management strategies to improve sweet potato productivity.

scholarly journals Early-season Soil Moisture Deficit Reduces Sweetpotato Storage Root Initiation and Development

HortScience ◽  
2013 ◽  
Vol 48 (12) ◽  
pp. 1457-1462 ◽  
Author(s):  
Bandara Gajanayake ◽  
K. Raja Reddy ◽  
Mark W. Shankle ◽  
Ramon A. Arancibia
Keyword(s):  
Soil Moisture ◽  
Ipomoea Batatas ◽  
Root Formation ◽  
Developmental Process ◽  
Root Initiation ◽  
Storage Root ◽  
Storage Roots ◽  
Root Numbers ◽  
Functional Relationships ◽  
Wide Range

Sweetpotato [Ipomoea batatas (L.) Lam.] storage root formation is a complex developmental process. Little quantitative information is available on storage root initiation in response to a wide range of soil moisture levels. This study aimed to quantify the effects of different levels of soil moisture on sweetpotato storage root initiation and to develop functional relationships for crop modeling. Five levels of soil moisture, 0.256, 0.216, 0.164, 0.107, and 0.058 m3·m−3 soil, were maintained using sensor-based soil moisture monitoring and semiautomated programmed irrigation. Two commercial sweetpotato cultivars, Beauregard and Evangeline, were grown in pots under greenhouse conditions and treatments were imposed from transplanting to 50 days. Identification of storage roots was based on anatomical, using cross-sections of adventitious roots, and visual features harvested at 5-day intervals from 14 to 50 days after transplanting (DAT). Recorded time-series storage root numbers exhibited sigmoidal responses at all soil moisture levels in both cultivars. Time to 50% storage root initiation and maximum storage root numbers were estimated from those curves. Rate of storage root development was determined as a reciprocal of time to 50% storage root formation data. Time to 50% storage root initiation declined quadratically from 0.05 to 0.15 m3·m−3 soil moisture and increased slightly at the higher soil moisture levels in both the cultivars. Cultivars differed in time to 50% storage root initiation and the storage root developmental rate. Soil moisture optima for storage root initiation were 0.168 and 0.199 m3·m−3 soil, equivalent to 63% and 75% field capacity for cultivars Beauregard and Evangeline, respectively. The data and the inferences derived from the functional algorithms developed in this study could be used to advise growers to schedule irrigation more precisely, make planting decisions based on available soil moisture, and to develop sweetpotato crop models for field applications.

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

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kun Pan ◽  
Cheng Lu ◽  
Peixian Nie ◽  
Meizhen Hu ◽  
Xincheng Zhou ◽  
...  
Keyword(s):  
Manihot Esculenta ◽  
Acid Invertase ◽  
Starch Accumulation ◽  
Storage Root ◽  
Storage Roots ◽  
Sucrose Transport ◽  
Manihot Esculenta Crantz ◽  
Parenchyma Cells ◽  
Cassava Storage Root ◽  
Fibrous Roots

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.

Response mechanism of sweet potato storage root formation and bulking to soil compaction and its relationship with yield

2019 ◽  
Vol 45 (5) ◽  
pp. 755
Author(s):  
Wen-Qing SHI ◽  
Bin-Bin ZHANG ◽  
Hong-Juan LIU ◽  
Qing-Xin ZHAO ◽  
Chun-Yu SHI ◽  
...  
Keyword(s):  
Sweet Potato ◽  
Soil Compaction ◽  
Root Formation ◽  
Potato Storage ◽  
Storage Root ◽  
Response Mechanism

scholarly journals Stratigraphic revision and reconstruction of the deep-sea fan of the Voirons Flysch (Voirons Nappe, Chablais Prealps)

2021 ◽  
Vol 114 (1) ◽  
Author(s):  
Jérémy Ragusa ◽  
Lina Maria Ospina-Ostios ◽  
Pascal Kindler ◽  
Mario Sartori
Keyword(s):  
Deep Sea ◽  
Distal Part ◽  
Accretionary Prism ◽  
Proximal Part ◽  
Late Eocene ◽  
Lithostratigraphic Units ◽  
Stratigraphic Record ◽  
Sea Fan ◽  
Stratigraphic Evolution ◽  
Depositional Setting

AbstractThe Voirons Flysch (Caron in Eclogae Geologicae Helvetiae 69:297–308, 1976), is a flysch sequence aggregated into the sedimentary accretionary prism of the Chablais and Swiss Prealps. Its palaeogeographic location is still debated (South Piemont or Valais realm). We herein present a stratigraphic revision of the westernmost unit of the former Gurnigel Nappe sensu Caron (Eclogae Geologicae Helvetiae 69:297–308, 1976): the Voirons Flysch. This flysch is subdivided into three lithostratigraphic units at the formation level (the Voirons Sandstone, the Vouan Conglomerate, the Boëge Marl), with an additional unit (Bruant Sandstone) of uncertain attribution, ranging from the early Eocene to probably the late Eocene. We further propose a new model of the depositional setting of the deep-sea of the Voirons Flysch based on palaeocurrent directions, the overall geometry and sedimentary features. This model depicts an eastward deflected deep-sea fan. The stratigraphic record of the proximal part of this fan is fairly complete in the Voirons area, whereas its most distal part is only represented by one small exposure of thinly bedded sandstones in the Fenalet quarry. The stratigraphic evolution of the Voirons Flysch shows two major disruptions of the detrital sedimentation at the transition between Voirons Sandstone—Vouan Conglomerate and Vouan Conglomerate—Boëge Marl. The cause of these disturbances has to be constrained in the framework of the palaeogeographic location of the Voirons Flysch.

scholarly journals A low-cost aeroponic phenotyping system for storage root development: unravelling the below-ground secrets of cassava (Manihot esculenta)

Plant Methods ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Michael Gomez Selvaraj ◽  
Maria Elker Montoya-P ◽  
John Atanbori ◽  
Andrew P. French ◽  
Tony Pridmore
Keyword(s):  
Root Growth ◽  
Root Development ◽  
Low Cost ◽  
Root Traits ◽  
Suitable Model ◽  
Root Initiation ◽  
Storage Root ◽  
Economic Traits ◽  
Storage Roots ◽  
Storage Root Development

Abstract Background Root and tuber crops are becoming more important for their high source of carbohydrates, next to cereals. Despite their commercial impact, there are significant knowledge gaps about the environmental and inherent regulation of storage root (SR) differentiation, due in part to the innate problems of studying storage roots and the lack of a suitable model system for monitoring storage root growth. The research presented here aimed to develop a reliable, low-cost effective system that enables the study of the factors influencing cassava storage root initiation and development. Results We explored simple, low-cost systems for the study of storage root biology. An aeroponics system described here is ideal for real-time monitoring of storage root development (SRD), and this was further validated using hormone studies. Our aeroponics-based auxin studies revealed that storage root initiation and development are adaptive responses, which are significantly enhanced by the exogenous auxin supply. Field and histological experiments were also conducted to confirm the auxin effect found in the aeroponics system. We also developed a simple digital imaging platform to quantify storage root growth and development traits. Correlation analysis confirmed that image-based estimation can be a surrogate for manual root phenotyping for several key traits. Conclusions The aeroponic system developed from this study is an effective tool for examining the root architecture of cassava during early SRD. The aeroponic system also provided novel insights into storage root formation by activating the auxin-dependent proliferation of secondary xylem parenchyma cells to induce the initial root thickening and bulking. The developed system can be of direct benefit to molecular biologists, breeders, and physiologists, allowing them to screen germplasm for root traits that correlate with improved economic traits.

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