Transcriptional profiling of sweetpotato (Ipomoea batatas) roots indicates down-regulation of lignin biosynthesis and up-regulation of starch biosynthesis at an early stage of storage root formation

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.

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Comparative Transcriptome Analysis of Storage Root Reveals Regulatory Mechanisms of Lignin Biosynthesis During Root Development in Two Sweetpotato Cultivars

10.21203/rs.3.rs-850254/v1 ◽

2021 ◽

Author(s):

Fuyun Hou ◽

Zhen Qin ◽

Taifeng Du ◽

Yuanyuan Zhou ◽

Aixian Li ◽

...

Keyword(s):

Root Development ◽

Ipomoea Batatas ◽

Molecular Mechanisms ◽

Signal Transduction Pathway ◽

Lignin Biosynthesis ◽

Storage Root ◽

Storage Roots ◽

Homologous Genes ◽

Phenylpropanoid Biosynthesis ◽

Storage Root Development

Abstract BackgroundSweetpotato(Ipomoea batatas (L.) Lam.) is one of the most important crops with high storage roots yield. Lignin affects the storage root formation. However, the molecular mechanisms of lignin biosynthesis in storage roots development have been lacking.ResultsTo reveal the molecular mechanism of lignin biosynthesis and identify new homologous genes in lignin biosynthesis during storage root development, the storage root (SR) at three different stages (D1, D2 and D3) in the two cultivars (Jishu25 and Jishu29) was investigated with full-length and second-generation transcriptome. A total of 52,137 transcripts and 21,148 unigenes were obtained after corrected with Hiseq2500 sequencing. Through the comparative analysis, 9577 unigenes were found to be differently expressed in the different stage in two cultivars. Among of them, 91 unigenes enriched in the phenylpropanoid biosynthesis, and 201 unigenes in hormone signal transduction pathway with KEGG analysis. Weighted gene co-expression network analysis of differentially expressed unigenes showed that lignin biosynthesis genes might be co-expressed with transcription factors such as AP2/ERF and MYB at the transcription level, and regulated by phytohormones auxin and GA3.ConclusionsTaken together, our findings will throw light on molecular regulatory mechanism of lignin biosynthesis involved in storage root development.

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Variation in Phosphorus Availability, Root Architecture Attributes, and Onset of Storage Root Formation among Sweetpotato Cultivars

HortScience ◽

10.21273/hortsci15358-20 ◽

2020 ◽

Vol 55 (12) ◽

pp. 1903-1911

Author(s):

Arthur Villordon ◽

Jeffrey C. Gregorie ◽

Don LaBonte

Keyword(s):

Lateral Root ◽

Ipomoea Batatas ◽

Root Formation ◽

Primary Root ◽

Root Traits ◽

Primary Objective ◽

Specific Information ◽

Storage Root ◽

Planting Dates ◽

Species Specific

The primary objective of this work was to generate species-specific information about root architectural responses to variations in inorganic phosphate (Pi) availability at the onset of storage root formation among six sweetpotato (Ipomoea batatas) cultivars. Three Pi levels were used: 0 (low Pi); 0.17 (medium Pi); and 0.34 (high Pi) g/pot triple super phosphate (0N–46P–0K). The check cultivar ‘Bayou Belle’ (BB) consistently showed evidence of storage root formation at 15 days in adventitious roots (ARs) grown across three Pi levels and two planting dates (PDs). Storage root formation was also detected in ‘Orleans’ (OR) and ‘Beauregard’ (BX), but it was less consistent relative to BB. In general, BB had the lowest adventitious root (AR) number relative to the other cultivars, but the magnitudes of difference varied with Pi availability and PD. With the first PD, BX had a 45% higher AR number compared with BB in low Pi conditions; however, there were no differences in the second PD. Within cultivars, BX and Okinawa grown in low Pi showed combined 17% and 24% reductions in primary root length (PRL) relative to roots grown in high Pi. BB had a higher lateral root number (LRN) and lateral root density (LRD) across Pi levels, corroborating prior data regarding the association of these root architectural attributes with the onset of storage root formation. The experimental data support the hypothesis regarding the existence of genetic variation for Pi efficiency in sweetpotato and that some well-documented Pi-efficient root traits like high LRN and LRD are indirectly selected for in-breeding programs that focus on early storage root formation and stable yields across environments.

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Variation in Boron Availability Alters Root Architecture Attributes at the Onset of Storage Root Formation in Three Sweetpotato Cultivars

HortScience ◽

10.21273/hortsci16134-21 ◽

2021 ◽

pp. 1-7

Author(s):

Arthur Villordon ◽

Jeffrey C. Gregorie

Keyword(s):

Root Length ◽

Ipomoea Batatas ◽

Root Formation ◽

Leaf Tissue ◽

Primary Objective ◽

Model Systems ◽

Specific Information ◽

Storage Root ◽

Main Root ◽

Crop Species

The primary objective of this work was to generate species-specific information about root architectural adaptation to variation in boron (B) availability at the onset of storage root formation among three sweetpotato [Ipomoea batatas (L.) Lam] cultivars (Beauregard = BX; Murasaki = MU; Okinawa = OK). Three B levels were used: 0B (B was omitted in the nutrient solution, substrate B = 0.1 mg·kg−1), 1XB (sufficient B; 0.5 mg·kg−1), and 2XB (high B; 1 mg·kg−1). The check cultivar BX showed evidence of storage root formation at 15 days in 0B and 1XB, whereas cultivars MU and OK failed to show evidence of root swelling. The 1XB and 2XB levels were associated with 736% and 2269% increase in leaf tissue B in BX, respectively, relative to plants grown in 0B. Similar magnitudes of increase were observed in MU and OK cultivars. There were no differences in adventitious root (AR) count within cultivars but OK showed 25% fewer AR numbers relative to BX across all B levels. 0B was associated with 20% and 48% reduction in main root length in BX and OK, respectively, relative to plants grown in 1XB and 2XB. 2XB was associated with a 10% increase in main root length in MU relative to plants grown in 0B and 1XB. 0B was associated with reduced lateral root length in all cultivars but the magnitude of responses varied with cultivars. These data corroborate findings in model systems and well-studied crop species that B deficiency is associated with reduced root growth. These data can be used to further understand the role of cultivar-specific responses to variation in B availability in sweetpotato.

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

Frontiers in Plant Science ◽

10.3389/fpls.2020.609923 ◽

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.

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A novel effect of glycine on the growth and starch biosynthesis of storage root in sweetpotato (Ipomoea batatas Lam.)

Plant Physiology and Biochemistry ◽

10.1016/j.plaphy.2019.10.012 ◽

2019 ◽

Vol 144 ◽

pp. 395-403 ◽

Cited By ~ 1

Author(s):

Chuanzhe Li ◽

Wenjing Yao ◽

Jianping Wang ◽

Jidong Wang ◽

Yuchun Ai ◽

...

Keyword(s):

Ipomoea Batatas ◽

Starch Biosynthesis ◽

Storage Root

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Recent Progress in Molecular Studies on Storage Root Formation in Sweetpotato (Ipomoea batatas)

Japan Agricultural Research Quarterly JARQ ◽

10.6090/jarq.50.293 ◽

2016 ◽

Vol 50 (4) ◽

pp. 293-299 ◽

Cited By ~ 7

Author(s):

Masaru TANAKA

Keyword(s):

Ipomoea Batatas ◽

Recent Progress ◽

Root Formation ◽

Storage Root ◽

Molecular Studies

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

HortScience ◽

10.21273/hortsci.48.12.1457 ◽

2013 ◽

Vol 48 (12) ◽

pp. 1457-1462 ◽

Cited By ~ 14

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.

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RNA-Seq and iTRAQ reveal multiple pathways involved in storage root formation and development in sweet potato (Ipomoea batatas L.)

BMC Plant Biology ◽

10.1186/s12870-019-1731-0 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 13

Author(s):

Tingting Dong ◽

Mingku Zhu ◽

Jiawen Yu ◽

Rongpeng Han ◽

Cheng Tang ◽

...

Keyword(s):

Sweet Potato ◽

Ipomoea Batatas ◽

Root Formation ◽

Storage Root ◽

Rna Seq

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Variation in Root Architecture Attributes at the Onset of Storage Root Formation among Resistant and Susceptible Sweetpotato Cultivars Infected with Meloidogyne incognita

HortScience ◽

10.21273/hortsci10746-18 ◽

2018 ◽

Vol 53 (12) ◽

pp. 1924-1929

Author(s):

Arthur Villordon ◽

Christopher Clark

Keyword(s):

Meloidogyne Incognita ◽

Ipomoea Batatas ◽

Root Formation ◽

Lateral Roots ◽

Root System Architecture ◽

Nematode Infection ◽

Storage Root ◽

Root Knot Nematode ◽

Inoculum Level ◽

Area And Volume

In sweetpotato (Ipomoea batatas), the successful emergence and development of lateral roots (LRs), the main determinant of root system architecture (RSA), determines the competency of adventitious roots (ARs) to undergo storage root formation. The present study investigated the effect of three levels of root-knot nematode (RKN) inoculum of race 3 of Meloidogyne incognita on LR length, number, area, and volume in ‘Beauregard’, ‘Evangeline’, and ‘Bayou Belle’, sweetpotato cultivars which are highly susceptible, moderately resistant, and highly resistant, respectively, to M. incognita. The three RKN levels were control (untreated), medium (500 eggs/pot), and high (5000 eggs/pot). In general, the number of galls after 20 days for each cultivar was consistent across RKN levels and two planting dates (PDs). ‘Beauregard’ inoculated with medium and high RKN levels showed 2.9 and 18.9 galls on each AR, respectively. ‘Evangeline’ had 0.5 and 3.4 galls at medium and high RKN levels, respectively. By contrast, ‘Bayou Belle’ showed only 0.9 galls at the high inoculum level. There was a significant PD × cultivar effect and cultivar × RKN level effect for all root attributes. LR attributes varied within and among resistant and susceptible cultivars with a general trend for increase in all root growth attributes in response to RKN infection in the first (PD1) and second PD (PD2). ‘Evangeline’ showed relatively consistent within-cultivar increase across PD1 (medium and high RKN levels) and PD2 (medium RKN level only). LR length, number, area, and volume within ‘Evangeline’ plants subjected to high RKN increased 122%, 126%, 154%, and 136%, respectively, relative to the untreated control plants in PD1. ‘Evangeline’ (PD1 and PD2) and ‘Bayou Belle’ (PD1 only) showed significant increase in all root attributes relative to the susceptible ‘Beauregard’ at medium or high RKN levels. In PD1, LR length, number, area, and volume in ‘Evangeline’ plants subjected to high RKN increased 165%, 167%, 176%, and 190%, respectively, relative to ‘Beauregard’ plants at the same RKN level. These findings are consistent with some data in other systems wherein nematode infection is associated with cultivar-specific root compensatory growth and demonstrate how genotype and environment interact to modify root development responses. These data can be used to further understand the role of cultivar-specific responses to nematode infection and can lead to the consideration of root traits in selection strategies.

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