Screening of Extraction Methods for Protein from Potato Tubers

[Objectives]This study was conducted to screen different extraction methods for protein from potato tubers.[Methods]The bud eye,lateral and pith parts of Qingshu 168 and Kexin 1 were used as test materials,and were extracted by acetone extraction,trichloroacetic acid(TCA)extraction,salt extraction,alcohol extraction and phenol extraction,respectively.The protein contents of different parts were determined by spectrophotometry.A 2-factor randomized block design was used to study the effects of varieties,extraction methods,sampling parts and combinations of different factors on protein content.[Results]The protein contents of different varieties were different,and Qingshu 168 was significantly higher than Kexin 1(P<0.05),reaching 128.0 mg/L.The protein contents obtained by different extraction methods were different.Acetone extraction,salt extraction and TCA extraction showed no significant differences in the protein content,but they were significantly higher than phenol extraction and alcohol extraction(P<0.05).The protein contents obtained by the former three were in the range of153.3-159.7 mg/L.The protein content in the bud eye part of potato tubers was significantly higher than those in the lateral and pith parts(P<0.05),reaching140.7 mg/L.There were significant differences among different combinations of varieties,extraction methods and sampling parts(P<0.05).The comprehensive comparison showed that the salt extraction method was suitable for the bud eye part of Qingshu 168,and the TCA extraction method was suitable for the bud eye part of Kexin No.1.[Conclusions]This study provides a reference for potato protein extraction and further research.

Impact of soil compaction on the engineering properties of potato tubers

A study on a 30 hm2 field was conducted to assess the variability in soil compaction and to investigate its effect on the engineering properties of potato tubers in terms of tuber shape and key dimensions(length,width and thickness)and resistance to penetration,rupture and shear forces.Three soil compaction levels were spatially correlated with the engineering properties of potato tubers through linear regression and ANOVA test.The three compaction levels included a low level(C1)ranging between 1.2-1.9 MPa,a medium level(C2)with compaction levels between 2.0-2.3 MPa and a high level(C3)ranging between 2.4-2.9 MPa.Results revealed that there were no significant changes in the key tuber dimensions corresponding to the variability in soil compaction.However,inverse linear relationships were observed between soil compaction and the key tuber dimensions with R2 values of 77%,97%and 96%for length,width and thickness,respectively.Similarly,the soil compaction was shown to have no effect on the tuber resistance to compression and shear force.In contrast,the tuber resistance to penetration was significantly affected by soil compaction(p>F=0.0012).

Study on Mutagenic Effect of Cobalt-60 Irradiation on Potato

[Objective] This study aimed to investigate the mutagenic effect of cobalt- 60 irradiation on potato. [Method] Potato tubers of Favorita and Zhongshu No.3 were irradiated with 5, 10, 20, 30, 50 and 70 Gy of cobalt-60 γ-ray respectively, to explore the mutagenic effect of different doses of γ-ray heavy ion irradiation on potato. [Result] The results showed that the emergence rate, seedling rate, plant growth, yield and commodity of potato varied after irradiated with different doses of cobalt-60 γ-ray; 10Gy of cobalt-60 irradiation played a positive effect on the growth and development of potato, while high doses played a negative effect on the growth and development of potato. After cobalt-60 irradiation, the botanical traits of M1 gen- eration varied greatly, resulting in a number of beneficial mutation traits; some traits of M2 and M3 generations became stably inherited. [Conclusion] Cobalt-60 irradiation breeding is conducive to the variety improvement and germplasm innovation as an effective means of genetic improvement for potato.

Comparison of the Effects of H_2O_2 and Salicylic Acid on Alternative Respiratory Pathway in Aged Potato Tuber Slices

The influences of exogenous H 2O 2 and salicylic acid (SA) treatments on the alternative respiratory pathway (ARP) in aged potato (Solanum tuberosum L.) tuber slices were compared. The results showed that both H 2O 2(5.0 mmol/L) and SA (0.1 mmol/L) treatments had a significant inducing effect on ARP capacity (V alt ) and its ratio to total respiration (V alt /V t) in potato slices aged for 24 h. With a monoclonal antibody against the alternative oxidase (AOX), Western blotting results showed that both H 2O 2 and SA treatments increased the AOX expression levels in aged potato tuber slices. However, the results of oxygen isotope discrimination experiments showed that H 2O 2 had no influence on the in vivo ARP activity (ρV alt ) and its contribution to V t(expressed as ρV alt /V t) in potato slices aged for 24 h, but SA had a significant influence on the ρV alt and ρV alt /V t values of the aged potato tuber slices. These results indicate that there are differences between the effects of H 2O 2 and SA on ARP in plant tissues. Both of them possess the ability to induce ARP capacity through inducing AOX expression. However, SA can simultaneously stimulate the operation of ARP, but H 2O 2 can not.

Potato/Maize intercropping reduces infestation of potato tuber moth, Phthorimaea operculella(Zeller) by the enhancement of natural enemies

The potato tuber moth(PTM),Phthorimaea operculella(Zeller),is one of the most economically significant insect pests for potato in both field and storage worldwide.To evaluate the infestation,reduction of potato yield and the control efficacy for PTM,field tests were conducted in two seasons by intercropping of potato as the host plant with maize as a non-host plant of PTM.Three intercropping patterns were tested,which were 2 rows of potatoes with either 2,3,or 4 rows of maize(abbreviated 2 P:2 M,2 P:3 M,and 2 P:4 M),and the monocropped potato as the control,2 rows of potatoes,without maize,(abbreviated 2 P:0 M).Results showed that the population and infestation of PTM in the 2 P:3 M intercropping pattern was significantly lower than those in 2 P:2 M,2 P:4 M and the monocropping pattern of 2 P:0 M,due to the enhancement of natural enemies.Cumulative mines and tunneling in potato leaves in 2 P:3 M intercropping were significantly lower than those in 2 P:2 M and 2 P:4 M patterns.The population of parasitoids and the parasitism rate of PTM in intercropping pattern of 2 P:3 M were significantly higher than that in intercropping pattern of 2 P:2 M,2 P:4 M and monocropping pattern of 2 P:0 M.We conclude that the potato intercropped with maize reduced the adult and larva populations,and reduced the damage from PTM by enhancing the number of parasitoids and the level of parasitism.The greatest population density of parasitoids and parasitism rate were in the intercropping pattern of 2 rows of potatoes with 3 rows of maize.These data indicate that the host/non-host intercropping patterns can be used as a biological control tactic against PTM by enhancing the density of natural enemies in the agro-ecosystems.

Improved Nucleic Acid Spot Hybridization Technique for Detection of Potato Spindle Tuber Viroid(PSTVd)

Potato spindle tuber viroid(PSTVd)disease is one of the major diseases that threatens potato production.Therefore,an advanced,rapid and sensitive detection technology is needed to detect the disease for better control.In order to establish an easier nucleic acid spot hybridization(NASH)method,some studies were tried as the followings:(1)the pre-hybridization step of nucleic acid spot hybridization(NASH)was omitted compared with ordinary way;(2)RNA extraction(phenol extraction and Ames buffer extraction)methods were compared;(3)fixed RNA by UV lamp and oven compared with UV cross-linker;(4)hybridized the RNA in shaking incubator and so on.The results showed that RNA extracted by Ames buffer was more effective than by the phenol extraction method.Besides,the result of hybridization without pre-hybridization step was better than that with 1.5 h of pre-hybridization.The more important discovery was that the shaking incubator could replace the hybridization oven and the ordinary UV lamp could replace the UV cross-linker.After a long term repeated research and testing,a new hybridization system that could rapidly detect the PSTVd by improved NASH technique merely using common instruments and equipment was established.

Detection of Potato Spindle Tuber Viroid, and Its Impact on Growth, Production of Tomatoes in Greenhouse

The viability of most tomato varieties cultivated in Libya have been tested to infect with potato spindle tuber viroid/potatoes （PSTVd） and its impact on growth and production of some of these varieties, which were mechanically inoculated with Libyan isolate of viroid PSTVd as follows： Vlkato, Sankarh, Lebda, Jasmine, Kenza and Hana. The percent of incidence were 95.95%, 90%, 90.80%, 80% and 20%, respectively. The following varieties have been contagious mechanically with viroid of PSTVd： Vlkato, zahra, Toria, Lebda, Hoda, Farwa, Alkaraz, Naziha, Rim Star and Kartika. The percent of incidence were 95.95%, 85%, 85.80%, 80%, 70.40%, 0.0%, 0.0%, respectively. The varied symptoms of wrinkle, twist, warp, swell the veins of the leaves, dark brown spots formation and a large yellow spots turned into white patches. Also the effect of the Egyptian isolate viroid PSTVd in the growth and production of varieties Jasmine, Lebda, Soberhalim, and treasure No. 185 had been studied, as the average rates of decline in the production of the fruits tomatoes/tomato 43.4% and 17% length of plants, and in the fresh weight and dry root of the sum of 35% and 37% respictively.

Biological Control of Erwinia carotovora ssp. carotovora by Streptomyces Species

Ten isolates of Erwinia carotovora ssp. carotovora (Ecc) were isolated from infected potato tubers of Picasso, Sante, and Nevskiy varieties collected from different regions in Kyrgyzstan. Isolates were identified as Erwinia carotovora ssp. carotovora (Ecc) by standard bacteriological techniques and pathogenicity tests on tubers and also by PCR analyses. Tests on the pathogenicity of E. carotovora ssp. carotovora (Ecc) strains to host plants by artificial inoculation have shown a high sensibility of the Picasso variety. As a result, five isolates were chosen, three isolates (EcPo1, EcPo2, and Eco3) were highly pathogenic, while two isolates (Eco4 and Eco5) were weakly pathogenic. The antagonistic bacteria, Streptomyces diastatochromogenes strain sk-6, and Streptomyces graminearuss strain sk-2, have a highly significant effect on soft rot bacteria isolates (Ecc), more than the other tested antagonistic organisms in vitro screening biotests. The Streptomyces diastatochromogenes sk-6 was selected for the control assay of storage potatoes against the most common soft rot bacterial strain in Kyrgyzstan, Erwinia carotovora sp. carotovora EcPo2. The pretreatment of potato tubers with antagonistic bacteria successfully prevented the initial infection multiplication of soft rot bacteria and reduced soft rot disease of potatoes in storage. These results justify selection of the dose 106 cells/ml of bacteria Streptomyces diastatochromogenes sk-6 for use in powdering the infected or non-infected potato tubers to suppress the development soft rot during storage. Streptomyces diastatochromogenes sk-6 as a biological disinfectant could destroy surface and internal infections, protect the tubers from the growth of phytopathogenic bacteria in the early period of their reproduction, and improve the overwintering of winter crops.

Decoding Phthorimaea operculella(Lepidoptera: Gelechiidae) in the new age of change

Arthropods and pathogens constantly challenge potato Solanum tuberosum L.production.Scenarios of climate variation have increased the possibility of changes in pests’biological and ecological patterns by increasing or reducing overwintering length,changes in population growth rates,number of generations,crop-pest relationship,and therefore affecting their expansion.Phthorimaea operculella Zeller(Lepidoptera:Gelechiidae)is one of the main pests affecting potatoes worldwide.Adults oviposit single or multiple eggs in leaves,stems,and tubers,while the larvae in immature stage mine leaves or burrows into tubers turning them unmarketable.Traditional control methods are effective in controlling P.operculella,but many factors determine the success of the control chosen.This review provides key highlights of current information available that could be used as a resource to fight this pest.

Precautionary analysis of sprouting potato eyes using hyperspectral imaging technology

Sprouted potatoes are not allowed for healthy diet.A good knowledge of the sprouting stage of potatoes can help manage the storage conditions and guide market distribution,thus enabling the quality assurance of potatoes on table.This article presented an intelligent method for precautionary analysis of potato eyes based on hyperspectral imaging technique.Potential potato eyes were classified into two categories according to the time gap to the sprouting date,i.e.by-sprouting and pre-sprouting potato eyes,representing eyes about to sprout and eyes that will take a while to sprout.Features used for classification were extracted by two methods,including successive projections algorithm(SPA)and a newly-developed sine fit algorithm(SFA).Then classifiers of fisher discriminant analysis(FDA)and least square support vector machine(LSSVM)were utilized for classification of potential sprouting potato eyes.Results showed that FDA was more effective than LSSVM in classifying pre-sprouting and by-sprouting potato eyes,and SFA performed well in FDA classifier with the recognition accuracy of 95.3%for prediction set.It is concluded that hyperspectral imaging has the potential for predicting the sprouting stages of potato eyes.

Tecia solanivora infestation increases tuber starch accumulation in Pastusa Suprema potatoes

In response to infestation with larvae of the Guatemalan tuber moth （Tecia solanivora）, some Solanum tuberosum （potato） varieties exhibit an overcompensa- tion response, whereby the total dry mass of uninfested tubers is increased. Here, we describe early responses, within the first few days, of T. solanivora feeding, in the Colombian potato variety Pastusa Suprema. Non- targeted metabolite profiling showed significant second- ary metabolism changes in T. solanivora-infested tubers, but not in uninfested systemic tubers. In contrast, changes in primary metabolism were greater in unin- fested systemic tubers than in the infested tubers, with a notable 80% decline in systemic tuber sucrose levels within 1 d of T. solanivora infestation. This suggested either decreased sucrose transport from the leaves or increased sink strength, i.e., more rapid sucrose to starch conversion in the tubers. Increased sucrose synthesis was indicated by higher rubisco activase and lower starch synthase gene expression in the leaves of infested plants. Elevated sink strength was demonstrated by 45% more total starch deposition in systemic tubers of T. solanivord- infested plants compared to uninfested control plants. Thus, rather than investing in increased defense of uninfested tubers, Pastusa Suprema promotes deposition of photoassimilates in the form of starch as a response to T. solanivora infestation.