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Sustaining the fourfold increase in blueberry (Vaccinium sp.) production witnessed during the previous two decades requires better understanding of its mineral nutrient physiology. The primary goals of this review are to evaluate our current understanding of the physiology of nitrogen (N) and calcium (Ca) nutrition in blueberry. Nitrogen concentration in blueberry ranges from 0.4% to >2% across organs. Blueberry uses N in various forms (organic and inorganic), but it appears to display preference for ammonium (NH4 +) over nitrate (NO3 −). The roles of N acquisition, translocation and assimilation in determining N-source preference in blueberry are evaluated. Calcium plays important roles in determining fruit quality owing to its function in maintaining cell wall and membrane integrity. It is unique in its translocation characteristics being transported primarily via the xylem. Fruit [Ca2+] typically declines from around 0.2% during early development to <0.05% at ripening. Modes of Ca acquisition and transport to the fruit, and various approaches to improve fruit [Ca2+] are discussed. Areas where further research is warranted to improve our understanding of N and Ca physiology in blueberry are identified. Such knowledge is essential for sustainable nutrient management, improving productivity, and enhancing fruit quality in blueberry.
John Doyle; Savithri Nambeesan; Anish Malladi. Physiology of Nitrogen and Calcium Nutrition in Blueberry (Vaccinium sp.). Agronomy 2021, 11, 765 .
AMA StyleJohn Doyle, Savithri Nambeesan, Anish Malladi. Physiology of Nitrogen and Calcium Nutrition in Blueberry (Vaccinium sp.). Agronomy. 2021; 11 (4):765.
Chicago/Turabian StyleJohn Doyle; Savithri Nambeesan; Anish Malladi. 2021. "Physiology of Nitrogen and Calcium Nutrition in Blueberry (Vaccinium sp.)." Agronomy 11, no. 4: 765.
Potassium (K) plays a crucial role in multiple physiological and developmental processes in plants. Its deficiency is a common abiotic stress that inhibits plant growth and reduces crop productivity. A better understanding of the mechanisms involved in plant responses to low K could help to improve the efficiency of K use in plants. However, such responses remain poorly characterized in fruit tree species such as pears (Pyrus sp). We analyzed the physiological and transcriptome responses of a commonly used pear rootstock, Pyrus betulaefolia, to K-deficiency stress (0 mM). Potassium deprivation resulted in apparent changes in root morphology, with short-term low-K stress resulting in rapidly enhanced root growth. Transcriptome analyses indicated that the root transcriptome was coordinately altered within 6 h after K deprivation, a process that continued until 15 d after treatment. Potassium deprivation resulted in the enhanced expression (up to 5-fold) of a putative high-affinity K+ transporter, PbHAK5 (Pbr037826.1), suggesting the up-regulation of mechanisms associated with K+ acquisition. The enhanced root growth in response to K-deficiency stress was associated with a rapid and sustained decrease in the expression of a transcription factor, PbMYB44 (Pbr015309.1), potentially involved in mediating auxin responses, and the increased expression of multiple genes associated with regulating root growth. The concentrations of several phytohormones including indoleacetic acid (IAA), ABA, ETH, gibberellin (GA3), and jasmonic acid (JA) were higher in response to K deprivation. Furthermore, genes coding for enzymes associated with carbon metabolism such as SORBITOL DEHYDROGENASE (SDH) and SUCROSE SYNTHASE (SUS) displayed greatly enhanced expression in the roots under K deprivation, presumably indicating enhanced metabolism to meet the increased energy demands for growth and K+ acquisition. Together, these data suggest that K deprivation in P. betulaefolia results in the rapid re-programming of the transcriptome to enhance root growth and K+ acquisition. These data provide key insights into the molecular basis for understanding low-K-tolerance mechanisms in pears and in other related fruit trees and identifying potential candidates that warrant further analyses.
Han Yang; Yan Li; Yumeng Jin; Liping Kan; Changwei Shen; Anish Malladi; Savithri Nambeesan; Yangchun Xu; Caixia Dong. Transcriptome Analysis of Pyrus betulaefolia Seedling Root Responses to Short-Term Potassium Deficiency. International Journal of Molecular Sciences 2020, 21, 8857 .
AMA StyleHan Yang, Yan Li, Yumeng Jin, Liping Kan, Changwei Shen, Anish Malladi, Savithri Nambeesan, Yangchun Xu, Caixia Dong. Transcriptome Analysis of Pyrus betulaefolia Seedling Root Responses to Short-Term Potassium Deficiency. International Journal of Molecular Sciences. 2020; 21 (22):8857.
Chicago/Turabian StyleHan Yang; Yan Li; Yumeng Jin; Liping Kan; Changwei Shen; Anish Malladi; Savithri Nambeesan; Yangchun Xu; Caixia Dong. 2020. "Transcriptome Analysis of Pyrus betulaefolia Seedling Root Responses to Short-Term Potassium Deficiency." International Journal of Molecular Sciences 21, no. 22: 8857.
Blueberry fruit are perishable after harvesting due to fruit softening, water loss and susceptibility to pathogens. Light, especially blue light, increases the accumulation of anthocyanins and reduces postharvest decay in some fruits, but the effect of blue light on postharvest fruit quality attributes in blueberries is unknown. In this study, we evaluated the effect of blue light on fruit quality, anthocyanin accumulation and disease development during postharvest cold storage (2 °C–4 °C) in two experiments with southern highbush blueberry ‘Star’ and rabbiteye blueberry ‘Alapaha’. Overall, diurnal blue light did not affect postharvest fruit quality attributes, such as visual defects, fruit compression, skin puncture, total soluble solid content and titratable acidity, in the two cultivars compared with their respective controls (diurnal white light or continuous darkness). Further, there was no effect of blue light on fruit color and anthocyanin accumulation. Fruit disease incidence in ‘Star’ ranged from 19.0% to 27.3% after 21 days and in ‘Alapaha’ from 44.9% to 56.2% after 24 days in postharvest storage, followed by 4 days at room temperature, but blue light had no consistent effect on postharvest disease incidence for either cultivar. Disease progression following artificial inoculations with Alternaria tenuissima and Colletotrichum acutatum in ‘Star’ was not influenced by light treatment prior to inoculation and during fruit storage. In a separate experiment, we tested the effect of blue light on color development in ‘Farthing’, a southern highbush blueberry cultivar with fruit prone to non-uniform ripening, whereby the stem-end remains green as the rest of the fruit turns blue. Although green stem-end spots turned blue over time, there was no statistically significant effect of the blue light treatment. Overall, these data indicate that blue light does not affect fruit quality attributes or disease development in ripe blueberry fruit during postharvest storage in the conditions investigated here.
Yi-Wen Wang; Helaina Ludwig; Harald Scherm; Marc van Iersel; Savithri Nambeesan. Blue Light Does Not Affect Fruit Quality or Disease Development on Ripe Blueberry Fruit During Postharvest Cold Storage. Horticulturae 2020, 6, 59 .
AMA StyleYi-Wen Wang, Helaina Ludwig, Harald Scherm, Marc van Iersel, Savithri Nambeesan. Blue Light Does Not Affect Fruit Quality or Disease Development on Ripe Blueberry Fruit During Postharvest Cold Storage. Horticulturae. 2020; 6 (4):59.
Chicago/Turabian StyleYi-Wen Wang; Helaina Ludwig; Harald Scherm; Marc van Iersel; Savithri Nambeesan. 2020. "Blue Light Does Not Affect Fruit Quality or Disease Development on Ripe Blueberry Fruit During Postharvest Cold Storage." Horticulturae 6, no. 4: 59.
Background Expansins (EXPs) facilitate non-enzymatic cell wall loosening during several phases of plant growth and development including fruit growth, internode expansion, pollen tube growth, leaf and root development, and during abiotic stress responses. In this study, the spatial and temporal expression patterns of C. annuum α- EXPANSIN (CaEXPA) genes were characterized. Additionally, fruit-specific CaEXPA expression was correlated with the rate of cell expansion during bell pepper fruit development. Results Spatial expression patterns revealed that CaEXPA13 was up-regulated in vegetative tissues and flowers, with the most abundant expression in mature leaves. Expression of CaEXPA4 was associated with stems and roots. CaEXPA3 was expressed abundantly in flower at anthesis suggesting a role for CaEXPA3 in flower development. Temporal expression analysis revealed that 9 out of the 21 genes were highly expressed during fruit development. Of these, expression of six genes, CaEXPA5, CaEXPA7, CaEXPA12, CaEXPA14 CaEXPA17 and CaEXPA19 were abundant 7 to 21 days after anthesis (DAA), whereas CaEXPA6 was strongly expressed between 14 and 28 DAA. Further, this study revealed that fruit growth and cell expansion occur throughout bell pepper development until ripening, with highest rates of fruit growth and cell expansion occurring between 7 and 14 DAA. The expression of CaEXPA14 and CaEXPA19 positively correlated with the rate of cell expansion, suggesting their role in post-mitotic cell expansion-mediated growth of the bell pepper fruit. In this study, a ripening specific EXP transcript, CaEXPA9 was identified, suggesting its role in cell wall disassembly during ripening. Conclusions This is the first genome-wide study of CaEXPA expression during fruit growth and development. Identification of fruit-specific EXPAs suggest their importance in facilitating cell expansion during growth and cell wall loosening during ripening in bell pepper. These EXPA genes could be important targets for future manipulation of fruit size and ripening characteristics.
Andrés Mayorga-Gómez; Savithri U. Nambeesan. Temporal expression patterns of fruit-specific α- EXPANSINS during cell expansion in bell pepper (Capsicum annuum L.). BMC Plant Biology 2020, 20, 1 -12.
AMA StyleAndrés Mayorga-Gómez, Savithri U. Nambeesan. Temporal expression patterns of fruit-specific α- EXPANSINS during cell expansion in bell pepper (Capsicum annuum L.). BMC Plant Biology. 2020; 20 (1):1-12.
Chicago/Turabian StyleAndrés Mayorga-Gómez; Savithri U. Nambeesan. 2020. "Temporal expression patterns of fruit-specific α- EXPANSINS during cell expansion in bell pepper (Capsicum annuum L.)." BMC Plant Biology 20, no. 1: 1-12.
With the growing popularity of blueberries and the associated increase in blueberry imports and exports worldwide, delivering fruit with high quality, longer shelf-life, and meeting phytosanitary requirements has become increasingly important. The objective of this study was to determine the effects of electron beam irradiation using a new Electronic Cold-PasteurizationTM (ECPTM) technology on fruit quality, microbial safety, and postharvest disease development in two southern highbush blueberry cultivars, ‘Farthing’ and ‘Rebel’. Fruit packed in clamshells were subjected to four levels of ECPTM irradiation (0, 0.15, 0.5, and 1.0 kGy) and evaluated for fruit quality attributes, surface microbial load, and postharvest disease incidence during various storage times after treatment and cold storage. Overall, there was no effect of irradiation on visual fruit quality in either cultivar. Fruit firmness and skin toughness in ‘Farthing’ was reduced following irradiation at 1.0 kGy, but no such effect was observed in ‘Rebel’. Other fruit quality characteristics such as fruit weight, total soluble solids content, or titratable acidity were not affected. Irradiation at 1.0 kGy significantly reduced total aerobic bacteria and yeast on the fruit surface, and in the case of ‘Rebel’, also levels of total coliform bacteria. There was no significant effect of irradiation on postharvest disease incidence in these trials. Overall, data from this study suggests that an irradiation dose lower than 1.0 kGy using ECPTM can be useful for phytosanitary treatment in blueberry fruit while avoiding undesirable effects on fruit quality in a cultivar-dependent manner.
Savithri U. Nambeesan; John W. Doyle; Helaina D. Capps; Chip Starns; Harald Scherm. Effect of Electronic Cold-PasteurizationTM (ECPTM) on Fruit Quality and Postharvest Diseases during Blueberry Storage. Horticulturae 2018, 4, 25 .
AMA StyleSavithri U. Nambeesan, John W. Doyle, Helaina D. Capps, Chip Starns, Harald Scherm. Effect of Electronic Cold-PasteurizationTM (ECPTM) on Fruit Quality and Postharvest Diseases during Blueberry Storage. Horticulturae. 2018; 4 (3):25.
Chicago/Turabian StyleSavithri U. Nambeesan; John W. Doyle; Helaina D. Capps; Chip Starns; Harald Scherm. 2018. "Effect of Electronic Cold-PasteurizationTM (ECPTM) on Fruit Quality and Postharvest Diseases during Blueberry Storage." Horticulturae 4, no. 3: 25.
Ripening in blueberry fruit is irregular and occurs over an extended period requiring multiple harvests, thereby increasing the cost of production. Several phytohormones contribute to the regulation of fruit ripening. Certain plant growth regulators (PGRs) can alter the content, perception, or action of these phytohormones, potentially accelerating fruit ripening and concentrating the ripening period. The effects of three such PGRs—ethephon, abscisic acid, and methyl jasmonate—on fruit ripening were evaluated in the rabbiteye blueberry (Vaccinium virgatum) cultivars ‘Premier’ and ‘Powderblue’. Application of ethephon, an ethylene-releasing PGR, at 250 mg L−1 when 30–40% of fruit on the plant were ripe, accelerated ripening by increasing the proportion of blue (ripe) fruit by 1.5–1.8-fold within 4 to 7 days after treatment in both cultivars. Ethephon applications did not generally alter fruit quality characteristics at harvest or during postharvest storage, except for a slight decrease in juice pH at 1 day of postharvest storage and an increase in fruit firmness and titratable acidity after 15 days of postharvest storage in Powderblue. In Premier, ethephon applications decreased the proportion of defective fruit at 29 days of postharvest storage. Abscisic acid (600–1000 mg L−1) and methyl jasmonate (0.5–1 mM) applications did not alter the proportion of ripe fruit in either cultivar. These applications also had little effect on fruit quality characteristics at harvest and during postharvest storage. None of the above PGR applications affected the development of naturally occurring postharvest pathogens during storage. Together, data from this study indicated that ethephon has the potential to accelerate ripening in rabbiteye blueberry fruit, allowing for a potential decrease in the number of fruit harvests.
Yi-Wen Wang; Anish Malladi; John W. Doyle; Harald Scherm; Savithri U. Nambeesan. The Effect of Ethephon, Abscisic Acid, and Methyl Jasmonate on Fruit Ripening in Rabbiteye Blueberry (Vaccinium virgatum). Horticulturae 2018, 4, 24 .
AMA StyleYi-Wen Wang, Anish Malladi, John W. Doyle, Harald Scherm, Savithri U. Nambeesan. The Effect of Ethephon, Abscisic Acid, and Methyl Jasmonate on Fruit Ripening in Rabbiteye Blueberry (Vaccinium virgatum). Horticulturae. 2018; 4 (3):24.
Chicago/Turabian StyleYi-Wen Wang; Anish Malladi; John W. Doyle; Harald Scherm; Savithri U. Nambeesan. 2018. "The Effect of Ethephon, Abscisic Acid, and Methyl Jasmonate on Fruit Ripening in Rabbiteye Blueberry (Vaccinium virgatum)." Horticulturae 4, no. 3: 24.
Shoot branching is an important determinant of plant architecture and influences various aspects of growth and development. Selection on branching has also played an important role in the domestication of crop plants, including sunflower (Helianthus annuus L.). Here, we describe an investigation of the genetic basis of variation in branching in sunflower via association mapping in a diverse collection of cultivated sunflower lines. Detailed phenotypic analyses revealed extensive variation in the extent and type of branching within the focal population. After correcting for population structure and kinship, association analyses were performed using a genome-wide collection of SNPs to identify genomic regions that influence a variety of branching-related traits. This work resulted in the identification of multiple previously unidentified genomic regions that contribute to variation in branching. Genomic regions that were associated with apical and mid-apical branching were generally distinct from those associated with basal and mid-basal branching. Homologs of known branching genes from other study systems (i.e., Arabidopsis, rice, pea, and petunia) were also identified from the draft assembly of the sunflower genome and their map positions were compared to those of associations identified herein. Numerous candidate branching genes were found to map in close proximity to significant branching associations. In sunflower, variation in branching is genetically complex and overall branching patterns (i.e., apical vs. basal) were found to be influenced by distinct genomic regions. Moreover, numerous candidate branching genes mapped in close proximity to significant branching associations. Although the sunflower genome exhibits localized islands of elevated linkage disequilibrium (LD), these non-random associations are known to decay rapidly elsewhere. The subset of candidate genes that co-localized with significant associations in regions of low LD represents the most promising target for future functional analyses.
Savithri U Nambeesan; Jennifer R Mandel; John E Bowers; Laura F Marek; Daniel Ebert; Jonathan Corbi; Loren H Rieseberg; Steven J Knapp; John M Burke. Association mapping in sunflower (Helianthus annuus L.) reveals independent control of apical vs. basal branching. BMC Plant Biology 2015, 15, 84 .
AMA StyleSavithri U Nambeesan, Jennifer R Mandel, John E Bowers, Laura F Marek, Daniel Ebert, Jonathan Corbi, Loren H Rieseberg, Steven J Knapp, John M Burke. Association mapping in sunflower (Helianthus annuus L.) reveals independent control of apical vs. basal branching. BMC Plant Biology. 2015; 15 (1):84.
Chicago/Turabian StyleSavithri U Nambeesan; Jennifer R Mandel; John E Bowers; Laura F Marek; Daniel Ebert; Jonathan Corbi; Loren H Rieseberg; Steven J Knapp; John M Burke. 2015. "Association mapping in sunflower (Helianthus annuus L.) reveals independent control of apical vs. basal branching." BMC Plant Biology 15, no. 1: 84.