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Open access

Chuan Shen and Xia Li

Amorphophallus belongs to the family Araceae and contains a high-molecular-weight polysaccharide that was originally extracted from corms called Konjac glucomannan. During the past 10 years, a vast body of research of Amorphophallus konjac has been published. Based on the Web of Science literature database, this work used Co-Occurrence, VOSviewer, and SciMAT bibliometrics analysis software tools to conduct literature analyses and big data mining of Amorphophallus Konjac research from Jan. 2012 to Dec. 2021. Therefore, the present research sorted the development process of this field and analyzed the popular changes in research topics by combing through the visualization of the analysis results to systematically review and forecast the research of Amorphophallus Konjac-related fields. This work discusses current research trends and hotspots and explores and analyzes the content that needs improvement to provide a reference for follow-up research.

Open access

Emilee Gaulke and Irwin L. Goldman

Bacterial leaf spot (BLS) has emerged in the last few decades as an economically important disease of both table beet (Beta vulgaris ssp. vulgaris) and Swiss chard (Beta vulgaris ssp. cicla). BLS is caused by Pseudomonas syringae pv. aptata, which is spread readily on infected seeds. Symptoms appear as circular to irregular shaped, with a tan to dark brown center and a very dark border. Disease incidence and severity is dependent on cool, humid conditions and can vary widely year to year depending on the environment. Both the vegetative and reproductive phases of these biennial crops are susceptible to the pathogen. Table beet and Swiss chard commercial cultivars (n = 21), table beet breeding lines (n = 5), and table beet plant introductions (PIs) (n = 26) were screened for response to spray inoculation with P. syringae pv. aptata in a controlled greenhouse setting. Plants were rated for severity of symptoms using percent of the area of each pair of leaves (leaf set) with symptoms and an overall plant score assigned based on the scores for each leaf pair. Accessions varied in BLS susceptibility. PI accessions were most variable, with the area under the disease progress curve (AUDPC) ranging from 1.33 to 8.75. Highly significant differences among PIs were detected for disease scores in the vegetative stage, beginning 21 days after inoculation. Screens during the reproductive growth stage showed the least variation in AUDPC among PIs. Although cultivars varied less than PIs, good BLS resistance (low disease scores) was noted for ‘Touchstone Gold’, ‘Kestrel’, ‘Bull’s Blood’, ‘Rainbow’ chard, as well as PIs 222234 and NSL 28026. Accessions W451C, Red Cloud, Detroit Dark Red, and NSL 28020 were highly susceptible. There was no consistent association between disease score in the vegetative and reproductive phases, suggesting that breeders may need to screen for BLS in both phases of the biennial life cycle. The more resistant PIs or cultivars identified in this study can be used in future efforts to breed for host resistance to BLS and to establish mapping populations to better understand the genetic control of resistance, to aid in breeding efforts.

Open access

Xinwang Wang, Warren Chatwin, Keith Kubenka, Angelyn Hilton, Braden Tondre, Tommy Thompson, and LJ Grauke

Open access

Tony Reda, Pushparajah Thavarajah, William Bridges, William Whiteside, Robert Polomski, Emerson Ship, and Dil Thavarajah

Over half of global food waste occurs in retail and households, highlighting the importance of improving shelf life. Many factors affect shelf life, including storage temperature, harvest time, processing method, and packaging. Modified atmosphere packaging (MAP), such as nitrogen (N2), has been used to improve the shelf life of produce. This study aimed to determine the effect of nitrogen-enriched packaging on the shelf life of greenhouse- and garden-grown kale in raised beds outdoors. Five kale cultivars (Black Magic, Darkibor, Lacinato, Red Russian, and Westlander) were grown in the greenhouse, and four cultivars (Curly Roja, Dwarf Green Curled, Meadowlark, and Vates) outdoors in raised beds, harvested and stored in nitrogen-enriched or nonenriched bags for 6 days. Leaf water content, water activity, color, visual score, and texture were measured for each replicate. Nitrogen-enriched packaging did not affect the kale shelf life. Garden-grown kale exhibited significantly lower water activity (0.979 vs. 0.999) and noticeably lower water content (88.6 vs. 90.6%) than greenhouse-grown kale. The cultivars were significant for all factors tested except for texture on day 4 and change in light to dark (Δ L*) and blue to yellow (Δ b*) color ratios. At the end of the study, cultivars Darkibor and Curly Roja had the highest visual score (4.4) and texture (305 g), respectively. The high performance of ‘Darkibor’ and ‘Curly Roja’ in visual score and texture may be due to decreased (Δ L*) and (Δ b*) values and decreased water content and water activity values. Future breeding efforts focused on the shelf life of kale should use the top-performing cultivars identified in this study and a diverse genetic population tested in a range of environments to develop cultivars with a longer shelf life.

Open access

Elizabeth Mitcham, Claire Adkison, Nico Lingga, and Veronique Bikoba

Four cultivars of English walnut (Juglans regia) were evaluated by a trained taste panel after 6 and 12 months of storage. English walnuts were stored at 5, 15, or 25 °C, and at 40%, 60%, or 80% relative humidity within each temperature. Principal component analysis was used to compare taste, texture, and aroma attributes evaluated by the taste panel to objective indicators of English walnut quality including water activity, moisture content, free fatty acids, peroxide value, hexanal content, and kernel color. Temperature was found to significantly impact English walnut oxidation and perceived rancidity, whereas storage at high relative humidity affected English walnut texture and accelerated quality loss. Water activity was more strongly correlated to textural changes than moisture content. The effect of relative humidity was more pronounced at lower temperatures, leading to increased hydrolytic rancidity and free fatty acids. Peroxide value had higher and more significant correlation to sensory attributes related to rancidity than hexanal. Free fatty acids were not correlated to the rancid sensory attribute, but were significantly correlated to bitter. English walnuts stored at 5 °C with 40% or 60% relative humidity were associated with the sweet sensory attribute and L* value (light color). Kernel darkening was associated with bitter and rancid, but a causal relationship is unknown. Sensory quality of English walnuts is complex and requires further study to establish thresholds for chemical indices of English walnut quality loss based on organoleptic perception.

Open access

Davis D. Harmon, Darren H. Touchell, Thomas G. Ranney, Kedong Da, and Wusheng Liu

Methods of in vitro regeneration protocols were developed for three elite rose cultivars, Chewnicebell (Oso Easy Italian Ice®), Bucbi (Carefree Beauty™), and Cheweyesup (Ringo All-Star™). We evaluated the effects of different types and concentrations of auxins [dichlorophenoxyacetic acid (2,4-D) and trichlorophenoxyacetic acid (2,4,5-T)], carbohydrates [sucrose, glucose, and fructose], and cytokinins [thidiazuron (TDZ) and 6-bezylaminopurine (BAP)] on callus induction and regeneration from leaf explants. The greatest amount of regenerative callus was obtained on media containing 10 µM 2,4-D and 30 g·L−1 sucrose for Italian Ice® (40%), 10 µM 2,4-D and 60 g·L−1 glucose for Carefree Beauty™ (24%), and 5 µM 2,4,5-T and 30 g·L−1 sucrose for Ringo All-Star™ (32%). The greatest regeneration occurred when callus was transferred to media consisting of 1/2 MS media supplemented with 2.9 µM GA3 and 5 µM TDZ for Italian Ice® and Ringo All-Star™, and with 2.9 µM GA3 and 20 µM TDZ for Carefree Beauty™. Plantlets regenerated from callus were cultured on maintenance media and successfully transferred ex vitro. This study highlights the genotype-specific responses among rose cultivars and provides the first reports of in vitro regeneration for Italian Ice® and Ringo All-Star™.

Open access

Penghua Gao, Huanyu Wei, Jiani Liu, Zebin Chen, Ying Qi, Zhixing Wu, Feiyan Huang, and Lei Yu

Amorphophallus species are one of the main economic crops in the mountainous areas of southwest China. However, soft rot disease (Pectobacterium carotovorum ssp. carotovorum) is devastating for this crop. This study explored the Amorphophallus resistance mechanism against soft rot disease by analyzing transcriptome data using a weighted gene coexpression network analysis. The RNA sequencing of plants infected for 0, 12, 24, and 48 hours produced a total of 52.25 Gb of clean reads. A total of 29,096 genes were divided into 34 modules. Six modules of interest with the highest correlation with the target traits were selected to elucidate the resistance genes and pathways. The selected modules were enriched in the α-linolenic acid metabolism, phenylpropane biosynthesis, plant hormone signal transduction, and plant pathogen interaction pathways. Ultimately, AmBGLU, AmCAML, AmCDPK, AmLOX, and AmRBOHD were identified as genes of interest in the four significantly related metabolic pathways for real-time fluorescence quantitative polymerase chain reaction verification. The determination of salicylic acid (SA) and jasmonic acid (JA) in Amorphophallus muelleri and Amorphophallus konjac that suffered from soft rot disease showed that SA and JA were involved in the A. muelleri and A. konjac defense response against soft rot disease. Methyl jasmonate treatment delayed the onset of A. konjac soft rot disease. This study provides a reference for the interaction between Amorphophallus species and soft rot disease and the breeding of broad-spectrum and specific Amorphophallus cultivars that are resistant to soft rot disease.

Open access

Noel A. Madalla, Rony Swennen, Allan F. Brown, Cornel Massawe, Mpoki Shimwela, Daud Mbongo, Grace Kindimba, Jerome Kubiriba, Robooni Tumuhimbise, Asher W. Okurut, Sebastien Carpentier, Inge Van den Bergh, Rhiannon Crichton, Lewis Machida, Eva Weltzien, and Rodomiro Ortiz

East African banana (Musa sp.) breeding efforts have focused mainly on enhancing ‘Matooke’ productivity through the development of high-yielding, pathogen-resistant cultivars with adequate stability to contribute to regional food security. Before a breeding program can recommend promising cultivars for release, they must pass the sensory screens; be evaluated in the target population environments; and the data analyzed for yield, adaptability, and stability. Twenty-four primary and secondary triploid hybrids [NARITA (N)] derived from ‘Matooke’ bananas, six triploid local ‘Matooke’ cultivars, and one exotic cultivar were evaluated for their yield, adaptability, and stability across the East African region at three highland sites in Uganda’s western and central regions, as well as at three sites in Tanzania’s northeastern and southern highlands regions, from 2016–19. A randomized complete block design with four replicates was used for multisite trials. The mixed-model restricted maximum likelihood/best linear unbiased prediction approach, along with additive main effect multiplicative interaction model biplots, were used to dissect and visualize genotype-by-environment patterns. Following the likelihood ratio test, both genotype and interaction effects were highly significant, confirming the influence of genotype and site heterogeneity for selecting specific and broadly adapted cultivars. N23 had the greatest yield across all sites associated with adaptability and stability, outperforming the overall mean yield of all genotypes by 34.2%. In Tanzania, N27 (second), N7 (third), N18 (fourth), N4 (fifth), N12 (sixth), and N13 (seventh); and in Uganda, N17 (second), N18 (third), N2 (fourth), N8 (fifth), N13 (sixth), N12 (seventh), N4 (eighth), and N24 (ninth) demonstrated good adaptability and stability, as well as high yield. Furthermore, the fungal pathogen Pseudocercospora fijiensis had no significant effect (P > 0.05) on yield, stability, and adaptability of the hybrids. As a result, they can be introduced into areas where black leaf streak constrains banana production significantly and threatens farmers’ livelihoods. The average site yield potential ranged from 9.7 to 24.3 t⋅ha–1 per year. The best discriminating sites for testing breeding clones were Lyamungo in Tanzania and Sendusu in Uganda. Hence, these testing sites are recommended as ideal examples of locations for selecting superior genotypes.

Open access

Ruigang Wu, Chao Wang, Lili Yin, Kun Ran, and Liping Wang

Zinc finger–homeodomain (ZF-HD) proteins, a family of plant-specific transcription factors, play an important role in regulating plant growth and development, as well as responses to stress. Although ZF-HDs have been investigated in several model plants, no systematic studies have been reported in apple (Malus ×domestica). In this study, 14 putative ZF-HD genes were identified in the apple genome and characterized using bioinformatics tools. All members harbored complete canonical structures of the ZF-HD motif. Phylogenetic analysis demonstrated that ZF-HD genes in the genome of apple could be classified into four subfamilies, with high intragroup similarities. Gene-structure analysis revealed that although 11 MdZHDs had only one exon, MdZHD6 and MdZHD13 had two exons and MdZHD8 had six exons, suggesting limited variation among the apple ZHD genes. The expression profiles of MdZHD genes revealed their involvement in the growth and development of different tissues. Numerous binding sites for transcription factors, such as MYB, bZIP, and AP2, were found in the promoter region of the putative MdZHD genes. Nearly all putative MdZHDs were predicted to localize in the nucleus. Finally, the expression levels of the MdZHD genes under abiotic stress were examined in apple rootstock Malus hupehensis and the results showed that the expression of 10 MdZHD genes was induced in response to three abiotic stress factors. Exceptionally, the expression of MdZHD11 was not induced in response to any of the abiotic stress treatments, MdZHD12 was only induced in response to salt stress, and MdZHD7 and MdZHD9 were induced in response to both drought and salt stress. The present results provide valuable insights into the putative physiological and biochemical functions of MdZHDs in apple.