Breeding of ‘Manten-Kirari’, a non-bitter and trace-rutinosidase variety of Tartary buckwheat (Fagopyrum tataricum Gaertn.)

Here, we developed a new Tartary buckwheat cultivar ‘Manten-Kirari’, whose flour contains only trace amounts of rutinosidase and lacked bitterness. The trace-rutinosidase breeding line ‘f3g-162’ (seed parent), which was obtained from a Nepalese genetic resource, was crossed with ‘Hokkai T8’ (pollen parent), the leading variety in Japan, to improve its agronomic characteristics. The obtained progeny were subjected to performance test. ‘Manten-Kirari’ had no detectable rutinosidase isozymes in an in-gel detection assay and only 1/266 of the rutinosidase activity of ‘Hokkai T8’. Dough prepared from ‘Manten-Kirari’ flour contained almost no hydrolyzed rutin, even 6 h after the addition of water, whereas the rutin in ‘Hokkai T8’ dough was completely hydrolyzed within 10 min. In a sensory evaluation of the flour from the two varieties, nearly all panelists detected strong bitterness in ‘Hokkai T8’, whereas no panelists reported bitterness in ‘Manten-Kirari’. This is the first report to describe the breeding of a Tartary buckwheat cultivar with reduced rutin hydrolysis and no bitterness in the prepared flour. Notably, the agronomic characteristics of ‘Manten-Kirari’ were similar to those of ‘Hokkai T8’, which is the leading variety in Japan. Based on these characteristics, ‘Manten-Kirari’ is a promising for preparing non-bitter, rutin-rich foods.     

Characterization of a γ-tocopherol methyltransferase mutant gene in wild (Carthamus oxyacanthus M. Bieb.) and cultivated safflower (C. tinctorius L.)

Safflower (Carthamus tinctorius L.) seeds contain a high proportion of tocopherols (>90 %) in the α-tocopherol form. A mutant with a high concentration of γ-tocopherol (>85 %) was identified in germplasm of wild safflower (Carthamus oxyacanthus M. Bieb.) that showed strong introgression of C. tinctorius, which allowed selection of individuals of both species with high concentrations of either α- or γ-tocopherol. The trait is controlled by a γ-tocopherol methyltransferase (γ-TMT) locus. The objective of this research was to identify γ-TMT sequence mutations associated with the high γ-tocopherol trait. Full length genomic and cDNA sequences of the γ-TMT gene were obtained from plants of C. tinctorius and C. oxyacanthus with both tocopherol profiles. Sequences from high γ-tocopherol plants showed an 11 bp deletion in exon 6 of the γ-TMT gene that disrupted the reading frame and created a premature stop codon, resulting in a predicted protein with a drastically altered amino acid sequence downstream the frameshift site. The data suggested that the frameshift mutation was underlying the γ-TMT loss of function mutant allele that determines the high γ-tocopherol phenotype. The characterized sequence change of 11 bp deletion could be used directly as a functional marker for introgression of the high γ-tocopherol trait into elite safflower cultivars.     

Use of equilibrium modified atmosphere packaging for preservation of ‘San Antonio’ and ‘Banane’ breba crops (Ficus carica L.)

The purpose of this work was to study the effect of equilibrium modified atmosphere packaging on the stability of ‘San Antonio’ and ‘Banane’ breba fruit during postharvest cold storage by the use of three different microperforated films (1/50 mm, 1/30 mm, and 1/10 mm; ø = 100 μm). Gas composition in the wraps, weight loss, % disorder, and microbial counts were monitored during cold storage for 21 days. The tested microperforated films allowed the extension of cold storage time for brebas, minimizing weight loss and delaying the disorders due to fungal proliferation, especially M50 (1/50 mm). Total soluble solids (TSS), titratable acidity (TA), pH, firmness, and sensory quality were also evaluated. Among the tested microperforated films, M50 showed the best performance in terms of delaying physicochemical senescence processes of fruit. The breba cultivar had an important impact on the extension of cold storage. For ‘San Antonio’ and ‘Banane’ cultivars packaged with microperforated M50, the optimal time of cold storage was 14 and 21 days, respectively.     

Assessment of tissue culture-derived ‘Gala’ and ‘Royal Gala’ apples (Malus × domestica Borkh.) for somaclonal variation

To assess somaclonal variation, ‘Gala’ and ‘Royal Gala’ trees obtained via axillary and adventitious bud formation were compared ex vitro to conventionally grafted trees. In general, tissue culture-derived trees were relatively erect in comparison to grafted trees. Their branch angles were narrower than those of grafted trees. All trees that flowered had pink blossoms. There were no obvious differences in flowering time or in floral morphology. Most of the seven-year-old grafted control trees produced more fruits than either axillary or regenerated trees. Although there were differences in the range of fruit color between ‘Royal Gala’ and ‘Gala’ apples in both the control and tissue culture-derived plants (the fruits of ‘Royal Gala’ were darker red and more striped than those of ‘Gala’) and also in the degree of pigmentation from tree-to-tree, none of the variation exceeded that observed among apples harvested from an individual ‘Royal Gala’ or ‘Gala’ control tree for either the plants derived from axillary buds or adventitiously. Since both ‘Gala’ and ‘Royal Gala’ axillary buds showed very little somaclonal variation for the morphological and reproductive traits we studied, it appears that tissue culture may be a useful way to propagate these cultivars. This revised version was published online in August 2006 with corrections to the Cover Date.     

Detection of downy and powdery mildew resistance QTL in a ‘Regent’ × ‘RedGlobe’ population

One hundred and eighty six F₁ plants from a ‘Regent’ × ‘RedGlobe’ cross were used to generate a partial linkage map with 139 microsatellite markers spanning all 19 chromosomes. Phenotypic scores for downy mildew, taken over two years, confirmed a major resistance QTL (Rpv3) against downy mildew in the interval VVIN16-cjvh to UDV108 on chromosome 18 of ‘Regent’. This locus explained up to 62 % of the phenotypic variance observed. Additionally a putative minor downy mildew resistance locus was observed on chromosome 1 in one season. A major resistance locus against powdery mildew (Ren3) was also identified on chromosome 15 of ‘Regent’ in the interval UDV116 to VChr15CenGen06. This study established the efficacy of and validated the ‘Regent’-derived downy and powdery mildew major resistance genes/QTL under South African conditions. Closely linked SSR markers for marker-assisted selection and gene pyramiding strategies were identified.     

The development of females of the potato root eelworm, (Heterodera rostochiensis Woll.) on ‘tuber-pieces’ of susceptible and resistant potatoes

A method is described for determining the degree of resistance shown by potatoes to a non-aggressive biotype of the potato root eelworm, Heterodera rostochiensis Woll., using tuber slices inoculated with H. rostochiensis larvae. The degree of resistance assessed by this method was found to agree well with the results obtained by root screening. The tuber piece method of testing for resistance could be used when root screening is impracticable or in conjunction with it.     

Effect of gamma irradiation on the physico-chemical and visual properties of mango (Mangifera indica L.), cv. ‘Dushehri’ and ‘Fazli’ stored at 20 °C

The effect of γ-irradiation doses (0.3, 0.5, 0.7, 1.0, 6.0, 10.0 kGy) on different physico-chemical and visual properties of two Indian cultivars of mango, cv. ‘Dushehri’ and ‘Fazli’ was observed during storage at 20 °C for the evaluation of delayed ripening and extension of shelf-life. Visually all the irradiated fruit showed greener peel and lighter pulp throughout the storage, however, radiation injuries were present in ‘Dushehri’ treated with 6–10 kGy and in ‘Fazli’ with 1–10 kGy. Loss of fruit due to rotting was less in the irradiated samples, treated up to 1 kGy of both the cultivars. Irradiated fruit of both the cultivars at high doses (6–10 kGy) showed increased sugar content from 0 d, however, all the treated fruit registered a slower rate of increase of sugars with storage compared to the respective controls and those treated with the lower doses of 0.5 and 0.7 kGy attained peak sugar concentration later. Significant (p ≤ 0.05) textural deterioration could be detected immediately after irradiation, in ‘Dushehri’ at doses ≥1 kGy and in ‘Fazli’ at doses ≥0.7 kGy. However, low dose treated fruit (0.3–1 kGy) of both the cultivars softened at a considerably slower rate during storage and registered significantly greater fruit firmness (compression strength) throughout the storage period. Similarly, ‘Dushehri’ treated with 0.3–0.7 kGy and Fazli treated with 0.7 kGy registered significantly greater flesh firmness (shear strength). ‘Dushehri’ treated with 0.3–1 kGy and ‘Fazli’ with 0.5–1 kGy also registered significantly harder and tougher peel, as determined by puncture test, throughout the storage. Scanning electron microscopy (SEM) performed on 3rd and 2nd d of storage of ‘Dushehri’ and ‘Fazli’ respectively, revealed microstructural breakdown at and above 1 kGy in both cultivars. Cell separation could be observed in ‘Fazli’ even at 0.7 kGy. SEM also revealed that the control fruit were in a more advanced stage of ripening than the low dose treated fruit. The study showed the feasibility of low dose γ-irradiation on ‘Dushehri’ (0.3–0.7 kGy) and ‘Fazli’ (0.5 and 0.7 kGy) that induced useful delay in ripening and extension of shelf-life by a minimum of 3 and 4 d, respectively.     

Effect of gamma irradiation on the physico-mechanical and chemical properties of potato (Solanum tuberosum L.), cv. ‘Kufri Sindhuri’, in non-refrigerated storage conditions

The effects of γ-irradiation doses, 0.04, 0.08, 0.12 and 1 kGy, applied at two different postharvest times (5 and 30 days after harvest), were studied on the textural behaviour (puncture force, shear force, work done to puncture and shear, cohesiveness and gumminess), microstructure, reducing sugar, total sugar and tuber losses of potato (Solanum tuberosum L.), cv. ‘Kufri Sindhuri’, during storage at 22 °C (RH: 85–90%). The lowest dose (0.04 kGy) was sufficient to inhibit sprouting in potatoes exposed on day 5 but not in the tubers exposed on day 30. The irradiated, non-sprouted potatoes maintained their appearance during storage. Potatoes irradiated early appeared more sensitive to radiation-induced damage, resulting in excessive loss of tubers at 1 kGy but low doses (up to 0.12 kGy) did not increase the susceptibility of the tubers to rotting. No significant differences between reducing sugar and total sugar contents of the control and low dose irradiated tubers were observed after 120 d. High dose (1 kGy) induced blackening of the bud tissue, increased rotting percentage and poor textural quality. Increasing low doses (up to 0.12 kGy) progressively reduced the textural deterioration in the tubers during storage. The scanning electron micrographs of potatoes irradiated with 0.08–0.12 kGy showed intact cells with rigid cell walls, accounting for the higher textural values registered by the samples. Among the two treatment timings, ‘K. Sindhuri’ irradiated early after harvest (i.e., on day 5) with 0.08–0.12 kGy doses retained higher textural parameters compared to those irradiated after a delay (day 30). The study showed the potential effect of γ-irradiation for enhancing the storage life of potatoes in non-refrigerated storage.     

Genetic diversity and population structure of ‘Khao Kai Noi’, a Lao rice (Oryza sativa L.) landrace,revealed by microsatellite DNA markers

Rice (Oryza sativa L.) is the main food for people in Laos, where it has been grown and eaten since prehistory. Diverse landraces are grown in Laos. ‘Khao Kai Noi’, a landrace favored for its eating quality, is held in the nationwide collection of traditional landraces in the Lao national genebank. Genetic diversity is crucial for sustainable use of genetic resources and conservation. To investigate the genetic diversity of ‘Khao Kai Noi’ for conservation, we genotyped 70 accessions by using 23 polymorphic simple sequence repeat markers. The markers generated 2 to 17 alleles (132 in total), with an average of 5.7 per locus. The total expected heterozygosity over all ‘Khao Kai Noi’ accessions was 0.271. Genetic variation was largest among accessions and smallest within accessions. Khao Kai Noi accessions were classified into three different genetic backgrounds, but there was unclear association between the three inferred population and name subgroups and geographical distribution. Most of the accessions were clustered with temperate japonica and showed genetic relatedness to rice from neighboring provinces of Vietnam, suggesting a Vietnamese origin. The results of this study will contribute to the conservation, core collection and future breeding of the Khao Kai Noi population.     

Farmers’ management of peanut (Arachis hypogaea L.) diversity,their varietal preference traits and uses in Southern and Central Benin

Journal of Crop Science and Biotechnology - Peanut (Arachis hypogaea L.) is one of the major oilseed legumes contributing to food security in Benin. Unfortunately, several constraints hamper its...     

Development of a coupling-phase SCAR marker linked to the powdery mildew resistance gene ‘er1’ in pea (Pisum sativum L.)

Pea powdery mildew is one of the major constraints in pea production worldwide, causing severe seed yield and quality loss. The resistance is governed by a single recessive gene er1 in majority of resistant cultivars, but er2 and Er3 have also been reported. The objective of the study was to find out tightly linked sequence characterized amplified regions (SCAR) markers to er1 gene using NILs. A total of 620 random amplified polymorphic DNA (RAPD) markers were screened for length polymorphism between seven sets of NILs. The 880 bp polymorphic band of the tightly linked RAPD marker OPX 04₈₈₀ was cloned, sequenced and a SCAR marker ScOPX 04₈₈₀ was developed. In a population of completely classified 208 F₂ plants (supported by phenotypic data from 208 F_2:3 and 4,390 F_3:4 families) ScOPX 04₈₈₀ was linked at 0.6 cM in coupling phase with er1 gene in the order ScOPX 04₈₈₀–er1–ScOPD 10₆₅₀. ScOPX 04₈₈₀ will correctly differentiate homozygous resistant plants from the susceptible accessions with more than 99 % accuracy. In combination with repulsion phase marker ScOPD 10₆₅₀, ScOPX 04₈₈₀ can help in an error free marker-assisted selection.     

Effect of hot water treatments on chilling injury and expression of a new C-repeat binding factor (CBF) in ‘Hongyang’ kiwifruit during low temperature storage

Kiwifruit is cold-sensitive and very susceptible to chilling injury (CI) during low temperature storage. In this study, kiwifruit (Actinidia chinensis cv. Hongyang) were pre-treated by water dip for 10 min at 20 (control) or 35, 45, or 55 °C (heat pretreatments) and then stored at 0 °C for 90 days to investigate the effect of hot water treatments (HWT) on chilling injury tolerance. Results showed that 35 °C and 45 °C HWT alleviated but did not completely prevent chilling injury development. By contrast, 55 °C HWT increased symptoms of chilling injury. The 45 °C HWT was the most effective at reducing chilling injury index and incidence. Compared with the other HWT, fruit treated at 45 °C exhibited higher firmness and soluble solids content (SSC), and lower malondialdehyde (MDA) content, lipoxygenase (LOX) activity and ethylene production rate. C-repeat/dehydration-responsive element binding factors (CBFs) are key regulators in cold response. To investigate the molecular regulation of HWT on chilling tolerance of kiwifruit, a 637 bp CBF gene was identified and the relative expression of AcCBF was measured by RT-qPCR. In accordance with the effects of HWT on physiological parameters of chilling injury, AcCBF expression level was highest in the 45 °C HWT. These results indicate that HWT at 45 °C for 10 min prior to low temperature storage is effective for alleviating symptoms of chilling injury in ‘Hongyang’ kiwifruit.     

Effect of sustained deficit irrigation on physicochemical properties,bioactive compounds and postharvest life of pomegranate fruit (cv. ‘Mollar de Elche’)

In this study, the influence of sustained deficit irrigation (SDI; 32% of reference evapotranspiration (ET₀)) on physicochemical and sensory quality and bioactive compounds of pomegranates stored for 30, 60 and 90 days in air at 5 °C + 4 days at 15 °C, at each storage period, was studied and compared to a control (100% ET₀). Fruit from SDI had higher peel redness and greater firmness, soluble solids contents, vitamin C (27%), phloretin (98%) and protocatechuic acid (10%) levels, and total antioxidant capacity (TAC) (46%) than the control. Cold storage and shelf-life did not induce significant changes in soluble solids, pH, titratable acidity, and chroma and Hue. SDI fruit had retarded development of chilling injury (CI) symptoms, which appeared after 60 days of storage in comparison to 30 days in the controls. Anthocyanins, catechin, phloretin and protocatechuic, caffeic, p-coumaric and caffeic acids contents had greater increases in SDI fruit than in controls throughout the postharvest life. TAC was significantly (P < 0.05) correlated to anthocyanins, gallic acid and total vitamin C contents. Generally, after long term storage, the fruit grown under SDI showed higher sensory and nutritional quality, more health attributes and a longer shelf-life (up to 90 days at 5 °C + 4 at 15 °C) than fruit irrigated at 100% ET₀.     

Prestorage application of high carbon dioxide combined with controlled atmosphere storage as a dual approach to control Botrytis cinerea in organic ‘Flame Seedless’ and ‘Crimson Seedless’ table grapes

Pre-storage application of 40% CO₂ at 0 °C for 24 or 48 h and controlled atmosphere (12% O₂ + 12% CO₂) storage at 0 °C for up to eight weeks on decay control and quality of organic ‘Flame Seedless’ and ‘Crimson Seedless’ table grapes were studied as a postharvest disease control alternative. To simulate different potential field conditions, these organic treatments were applied to organic-grown grapes that were naturally infected (without inoculation), surface inoculated (berries inoculated by spraying with a conidia suspension), and nesting inoculated (clusters inoculated by placing in the middle an artificially infected berry) with the pathogen Botrytis cinerea, the cause of grape gray mold. Under these three conditions, a 40% CO₂ for 48 h pre-storage treatment followed by controlled atmosphere reduced the gray mold incidence from 22% to 0.6% and from 100% to 7.4% after four and seven weeks, respectively. High CO₂ pre-storage alone limited botrytis incidence in both naturally and artificially infected grapes, but was more effective when combined with CA. These treatments did not affect visual or sensory fruit quality. Exposure to high CO₂ for 24 or 48 h effectively inhibited mycelial growth of B. cinerea in PDA plates incubated at 22 °C for up to 72 h. Conidia germination in PDA plates was reduced ∼60% after 12 h incubation. In vitro studies demonstrated a fungistatic effect, but further studies on the mechanism of action could improve treatment performance. This novel high CO₂ initial fumigation followed by controlled atmosphere during storage or transportation could be a commercially feasible alternative for postharvest handling of organic and conventional table grapes. Our results encourage validating this combined physical treatment in other cultivars and under commercial conditions.