Using growing degree days, agrometeorological variables, linear regression, and data mining methods to help improve prediction of sweetpotato harvest date in louisiana

Predictive models of optimum sweetpotato (Ipomoea batatas) harvest in relation to growing degree days (GDD) will benefit producers and researchers by ensuring maximum yields and high quality. A GDD system has not been previously characterized for sweetpotato grown in Louisiana. We used a data set of 116 planting dates and used a combination of minimum CV, linear regression (LR), and several algorithms in a data mining (DM) mode to identify candidate methods of estimating relationships between GDD and harvest dates. These DM algorithms included neural networks, support vector machine, multivariate adaptive regression splines, regression trees, and generalized linear models. We then used candidate GDD methods along with agrometeorological variables to model US#1 yield using LR and DM methodology. A multivariable LR model with the best adjusted r2 was based on GDD calculated using this method: maximum daily temperature (Tmax) - base temperature (B), where if Tmax \u3e ceiling temperature [C (90°F)], then Tmax = C, and where GDD = 0 if minimum daily temperature \u3c60°F. The following climate-related variables contributed to the improvement of adjusted r2 of the LR model: mean relative humidity 20 days after transplanting (DAT), maximum air temperature 20 DAT, and maximum soil temperature 10 DAT (log 10 transformed). In the DM mode, this GDD method and the LR model also demonstrated high predictive accuracy as quantified using mean square error. Using this model, we propose to schedule test harvests at GDD = 2600. The harvest date can further be optimized by predicting US#1 yield using GDD in combination with climate-based predictor variables measured within 20 DAT

Genetic variation among sweetpotatoes propagated through nodal and adventitious sprouts

Genetic uniformity was assessed among sweetpotato (Ipomoea batatas ) clones propagated through adventitious and nodal procedures. A single sprout each of \u27Jewel.\u27 \u27Sumor,\u27 and L87-95 was used as source of clonal plants that were simultaneously propagated through conventional adventitious procedures and a tissue culture-based nodal culture technique. A sample of 15 decamer primers generated 64 scorable amplified fragments in a PCR-based assay. 29 of which were putatively polymorphic across n = 60 samples ( 10 each of nodal and adventitiously derived plants/genotype). Within adventitiously derived materials, putative polymorphisms ranged from 4.7 \u3c7r to\u3e3U\u3c£ depending on the genotypic class. In contrast, putative polymorphisms ranged from 0.0\u3c£ to 3.1 **• among nodally derived samples. Marker loci differen-tiated genotypes as well as putative marker phenotype variants through a multidimensional scaling analysis of the genetic similarity matrix. An \u27analysts of molecular variance\u27 shows that genotypic effects accounted for 88.7°«• of the total molecular marker variability, w hue propagation effects ( within genotypic groups I accounted for 1U4T. Results confirm that clonal plants derived from preexisting meristematic regions arc more genetically uniform than plants propagated from adventitious origins

Isolation and characterization of cDNA clones encoding a novel subfamily sporamin B in sweet potato

Three cDNAs (IbH23, IbH41, and IbH74) encoding sporamin of sweet potato, were isolated from a skinning injury cDNA library. The open reading frame consisted of 288 nucleotides and the deduced polypeptide sequences consist of 96 amino acids with missing 127 amino acid residues at 5′. The sequences shared identity [42-62% (IbH23 and IbH41) and 40-61% (IbH74)] to sporamins A and B previously identified in other sweet potato species. The IbSpors contained three of four signature cysteine residues of sporamin family (Cys135, Cys198, Cys209). In addition to similarity to sporamins, these cDNA clones also showed similarities to miraculin (29-35%); Kunitz trypsin inhibitor (29-36%); factor Xa inhibitor (32-38%); subtilisin inhibitor (26-37%); seed protein (32%); tumor-related protein (36% in IbH23 and IbH41); and [wound-responsive protein (30%), sexual organ responsive protein (29%), and proteinase inhibitor (26%) can only be found in IbH74]. The three partial mRNA transcripts showed induced and transient expression in response to skinning injury. The phylogenetic analysis revealed that they belonged to a new member of sporamin gene subfamily B and may play key roles in plant defense and wound repair in response to skinning injury in storage roots of sweet potato

Effect of drought on storage root development and gene expression profile of sweetpotato under greenhouse and field conditions

Greenhouse and field culture systems were used to study the effect of drought conditions on the storage root (SR) formation in \u27Beauregard\u27 sweetpotato (Ipomoea batatas). In the greenhouse culture system, drought was simulated by withholding water for 5 and 10 days after transplanting (DAT) cuttings in dry sand. Control plants received water at planting and every 3 days thereafter. In the field studies, natural drought conditions and selective irrigation were used to impose water deprivation during the critical SR formation period. Greenhouse drought for 5 and 10 DAT reduced the number of SRs by 42% and 66%, respectively, compared with the controls. Field drought resulted in a 49% reduction in U.S. #1 SR yield compared with the irrigated condition. Quantitative real-time polymerase chain reaction (PCR) analysis showed differential expression of a set of sweetpotato transcription factors and protein kinases among greenhouse-grown plants subjected to well-watered conditions and water deficit during 5 DAT. A significant enhancement of expression was observed for known drought stress-associated genes such as an abscisic acid-responsive elements-binding factor, dehydration-responsive element-binding factor, and homeodomain- zip proteins. Members of calcium-binding proteins showed differential expression under drought stress. For the first time it is reported that knotted1-like homeobox and BEL1-like genes showed altered expression in response to drought stress under a greenhouse condition. In summary, the results suggest that water deprivation during the SR formation period influences root development and expression patterns of stress-responsive genes and those previously found associated with SR formation in sweetpotato

Skinning Injury Responses in Sweetpotato

In sweetpotatoes (Ipomoea batatas L. Lamb), the loss of skin from the surface of the storage roots is known as skinning injury. It is responsible for significant postharvest loss resulting from moisture increase and weight reduction, wrinkling, and susceptibility to pathogen attack. Reduced root weight by water loss is associated with a higher rate of rot predominantly occurred in the developing and underdeveloped countries which can count of 8-20% of postharvest loss. Plants have different adaptation to protect themselves against skinning injury. Lignification, suberization, and increased sugar at the wound site have been shown to be correlated with wound healing. Changing in gene expressions have been associated with skinning injury. Genes associated in the biosynthesis of lignin and suberin, protein fate, cell-wall modification, transcription and protein synthesis, and stress responses and defense have been associated with skinning injury responses in plants. Understanding the skinning injury responses and how to regulate them can be used to produce a more desirable plant resistant to skinning injury. This paper especially reviews and discusses skinning injury responses in sweetpotato, a root crop which product may severely be affected by skinning injury. Keywords: gene expression, Ipomoea batatas, lignification, postharvest loss, wounding   ABSTRAK Pada ubi jalar (Ipomoea batatas L. Lamb), cedera kulit adalah hilangnya kulit dari permukaan umbi. Cedera kulit ini bertanggung jawab atas kerugian pascapanen yang signifikan akibat peningkatan laju kelembaban dan penurunan berat umbi, pengerutan, dan kerentanan terhadap serangan patogen. Berat umbi yang berkurang karena kehilangan air dikaitkan dengan tingkat pembusukan yang lebih tinggi, terutama terjadi di negara-negara berkembang dan yang kurang berkembang dengan kehilangan hasil panen umbi 8-20%. Tanaman memiliki adaptasi yang berbeda untuk melindungi diri dari cedera kulit. Lignifikasi, suberisasi, dan peningkatan gula di lokasi pelukaan telah terbukti berkorelasi dengan penyembuhan luka. Perubahan ekspresi gen telah dikaitkan dengan cedera kulit. Gen-gen yang terlibat dalam jalur biosintesis lignin dan suberin, protein tujuan akhir, modifikasi dinding sel, transkripsi dan sintesis protein, serta respons stres dan pertahanan telah dikaitkan dengan respons cedera kulit pada tanaman. Memahami respons cedera kulit dan bagimana cara mengaturnya dapat digunakan untuk menghasilkan tanaman yang diinginkan yang tahan terhadap cedera kulit umbi. Paper ini secara khusus mengulas dan membahas respon cedera kulit pada ubi jalar, suatu tanaman umbian yang hasilnya sangat terpengaruh oleh cedera kulit. Kata kunci: ekspresi gen, Ipomoea batatas, lignifikasi, kehilangan pascapanen, pelukaa

Differential gene expression of resistant and susceptible sweetpotato plants after infection with the causal agents of sweet potato virus disease

Sweet potato virus disease (SPVD) is one of the most devastating diseases affecting sweetpotato (Ipomoea batatas), an important food crop in developing countries. SPVD develops when sweetpotato plants are dually infected with sweet potato feathery mottle virus (SPFMV) and sweet potato chlorotic stunt virus (SPCSV). To better understand the synergistic interaction between these viruses, global gene expression was previously studied in the susceptible cultivar Beauregard. In the current study, global gene expression between SPVD-affected plants and virus-tested control plants (VT) were compared in \u27Beauregard\u27 (Bx) and resistant \u27NASPOT 1\u27 (Nas) sweetpotato cultivars at 5, 9, 13, and 17 days post inoculation (DPI). Titer levels of SPFMV and SPCSV were significantly lower in inoculated resistant plants (Nas_SPVD) than in susceptible plants (Bx_SPVD) at most of the time points. Chloroplast genes and cell expansion-related genes (including xyloglucan endotransglucosylase/hydrolases) were suppressed in Bx_SPVD, while stress-related genes were induced. This trend was not observed in resistant NAS_SPVD. Genes related to protein synthesis (e.g., ribosomal proteins and elongation factor genes) were induced in resistant NAS_SPVD at 5 DPI before returning to levels comparable with NAS_VT plants. At this time (5 DPI), individual viruses could not be detected in NAS_SPVD samples, and no symptoms were observed. Induction of protein synthesis-related genes is common in susceptible plants after virus infection and is generally in proportion to virus accumulation. Our results show that induction of protein synthesis genes also occurs early in the infection process in resistant plants, while virus titers were below the level of detection, suggesting that virus accumulation is not required for induction

Influence of drought stress on sweetpotato resistance to sweetpotato weevil, Cylas formicarius (Coleoptera: Apoinidae), and storage root chemistry

The effect of drought stress on the resistance of sweetpotato roots to sweetpotato weevil (SPW), Cylas formicarius (Fab.), was studied in 1997 and 1998 in two genotypes ( Beauregard and Excel ) with different SPW susceptibility. Storage roots produced under drought or normal conditions were tested for adult feeding, oviposition, larval survival and pupal weight in the laboratory under no-choice and free-choice test conditions. The levels of sweetpotato resin glycoside and caffeic acid in the periderm tissue of the roots were also determined. Drought-stressed roots received significantly more SPW eggs under no-choice and free-choice conditions and more feeding punctures under free-choice conditions than non-stressed roots in 1997. Larval survival rate was significantly lower on drought-stressed roots. A significant drought effect on feeding, oviposition and larval survival was absent in 1998. Drought stress had no effect on sweetpotato resin glycosides content in both years, but significantly reduced the content of caffeic acid in 1997. Genotype had a significant effect on SPW feeding in 1997 and on feeding and oviposition in 1998 under free-choice test conditions, where Beauregard was preferred for both feeding and oviposition. Beauregard also supported a significantly higher larval survival rate compared with Excel. Resin glycosides or caffeic acid contents were similar for the two genotypes in 1997, while higher level of resin glycosides was detected in Excel than in Beauregard in 1998. The interaction between drought stress and genotype was significant for adult feeding under free-choice conditions and for larval survival, indicating a different response between the two genotypes

Differential Expression of Phosphate Starvation-responsive Genes among Sweetpotato Cultivars during Establishment and Onset of Storage Root Formation

It has been documented that sweetpotato (Ipomoea batatas L.) cultivars vary in morphological and physiological adaptations to low phosphorus (P) availability but knowledge of the underlying molecular mechanisms is largely unknown. The objective of this research was to generate cultivar-specific information about phosphate starvation response (PSR) genes to variations in inorganic phosphate (Pi) availability at the onset of storage root formation among sweetpotato cultivars. Cultivars Bayou Belle (BB), Evangeline (EV), and Orleans (OR) were grown under varying Pi levels: 0 mg·L−1 (low Pi), 15 mg·L−1 (Pi-sufficient), and 31 mg·L−1 (high Pi). Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) analysis of PSR genes IbPHR1, IbSPX1, IbSPX3, IbPHT1;4, IbPHT1;5, and IbNLA was performed at 5 and 10 days after planting (DAP), corresponding to adventitious root system establishment and the onset of storage root formation, respectively. The cultivar BB grown under low Pi showed significantly higher expression of all genes except IbPHR1. The cultivar OR grown in both low and high Pi exhibited upregulation of IbPHR1. On the other hand, EV grown under low Pi revealed no response for all genes investigated. Exposure of BB to high Pi resulted in a decrease in expression for all genes except IbNLA. The cultivar EV grown in high Pi conditions showed increase in expression for IbSPX1, IbPHT1;5, and IbNLA. Expression pattern difference among cultivars relative to Pi levels corroborates field observations showing that BB, EV, and OR have different Pi requirements. The increased activity of BB PSR genes grown under low Pi supports the hypothesis that BB requires low P fertilizer input relative to OR and EV. Results from this study corroborate findings from well-characterized crop species and model systems and pave the way for the development of tools and practices to increase phosphorus use efficiency in sweetpotato

Adventitious root primordia formation and development in stem nodes of ‘Georgia jet’ sweetpotato, Ipomoea batatas

PREMISE OF THE STUDY: Yield in sweetpotato is determined by the number of storage roots produced per plant. Storage roots develop from adventitious roots (ARs) present in stem cuttings that serve as propagation material. Data on the origin of sweetpotato ARs and the effect of nodal position on AR establishment and further development are limited. METHODS: We anatomically described root primordium initiation using stem sections and measured number of root primordia formed at different nodal positions using light microscopy and correlated nodal positions with AR number and length 14 d after planting (DAP). KEY RESULTS: Primordia for ARs initiate at the junction of the stem pith ray and the cambium, on both sides of the leaf gap, and they are well developed before emerging from the stem. The number of ARs that develop from isolated stem nodes 14 DAP corresponded to the number of AR primordia detected inside the stem. The total length of established roots at nodes 9-13 from the apex is about 2-fold longer than at nodes 5-8. CONCLUSIONS: Nodal position (age) has a significant effect on the developmental status and number of root primordia inside the stem, determining the number and length of ARs that have developed by 14 DAP. Adventitious roots originating from nodes 9-13 possess similar AR systems and develop better than those originating from younger nodes 3-8. The mechanism regulating AR initiation in nodes is discussed. This system can serve for studying the effect of environmental conditions on AR initiation, development, and capacity to form storage roots

Field performance of tissue-cultured, virus-tested ‘okinawan’ sweetpotato and comparison with some promising cultivars in hawai’i

Tissue-cultured, virus-tested (TC) plantlets of sweetpotato (Ipomoea batatas var. batatas) cultivars Okinawan, LA 08-21p, and Murasaki-29 were obtained from Louisiana State University Agricultural Center. The objectives of field trials conducted at the Kula Agricultural Park, Maui, HI, were to compare yield and pest resistance of 1) ‘Okinawan’ obtained from a commercial (C) field with TC ‘Okinawan’ and 2) TC Okinawan with the aforementioned TC cultivars. Trials were planted Oct. 2015 and Aug. 2016 and harvested 5 months later. Storage roots were graded according to State of Hawai’i standards, and marketable yields included Grades AA, A, and B. In addition, injuries due to sweetpotato weevil (Cylas formicarius elegantulus) or rough sweetpotato weevil (Blosyrus asellus) were estimated. In both trials, fresh and dry weights of marketable storage roots of TC ‘Okinawan’ were nearly twice those from commercial planting material. In both trials, marketable fresh weights differed among the three TC cultivars; however, significant interactions were found, indicating that yields of cultivars differed between years. In the first field trial, ‘LA 08-21p’ had fresh marketable yields 1.6 to 1.7 times greater than TC ‘Okinawan’ and Murasaki-29, respectively. In the second trial, fresh marketable yields of TC ‘Okinawan’ and ‘LA 08-21p’were similar and 1.7 to 1.5 times greater than that of ‘Murasaki-29’, respectively. In both trials, ‘LA 08-21p’ had greater sweetpotato weevil injury than did the other two cultivars. Interestingly, in the second year, TC ‘Okinawan’ had greater rough sweetpotato weevil injury than did the other cultivars. Our results indicate that tissue-cultured planting materials increased marketable yields of TC ‘Okinawan’ compared with C ‘Okinawan’ sweetpotato and that the other TC cultivars did not produce greater yields than TC Okinawan