scholarly journals Evaluation of Growth Regulator Inhibitors for Controlling Postbloom Fruit Drop (PFD) of Citrus Induced by the Fungus Colletotrichum acutatum

HortScience ◽  
2006 ◽  
Vol 41 (5) ◽  
pp. 1317-1321 ◽  
Author(s):  
Hui-Qin Chen ◽  
Katherine L. Dekkers ◽  
Lihua Cao ◽  
Jacqueline K. Burns ◽  
L. W. Timmer ◽  
...  
Keyword(s):  
Systemic Acquired Resistance ◽  
Auxin Transport ◽  
Sweet Orange ◽  
Acquired Resistance ◽  
Colletotrichum Acutatum ◽  
Yield Losses ◽  
Commercial Products ◽  
Young Fruit ◽  
Factors Associated ◽  
Fruit Drop

Postbloom fruit drop (PFD) of citrus is incited by the fungus Colletotrichum acutatum J. H. Simmonds and may result in young fruit drop and severe yield losses. Previous studies suggested that imbalance of growth regulators such as auxin, ethylene, and jasmonic acid (JA) plays an essential role in young fruit abscission. In this work, we determined the factors associated with fungal-induced fruit drop by testing compounds inhibitory to hormonal transport or biosynthesis. As assessed on sweet orange (Citrus sinensis Osbeck) and grapefruit (C. paradisi Macf.) for 4 years, we found that many auxin transport and action inhibitors such as 2,3,5-triiodobenzolic acid (TIBA), 2-(4-chlorophenoxy)-2-methyl-propionic acid (clofibrate), or quercetin and JA biosynthesis inhibitors such as salicylic acid (SA) and aspirin (methyl-SA) applied 7 d after C. acutatum infection resulted in higher percentages of young fruit retention compared with the water controls. The commercial products ReZist and Actigard, widely used as systemic acquired resistance (SAR) agents, also improved fruit retention. Furthermore, application of gibberellic acid (GA3) on sweet orange, regardless of C. acutatum infection, significantly increased fruit retention. These commercial products may be very useful in managing this destructive disease of citrus in the field.

scholarly journals Genes for Hormone Biosynthesis and Regulation Are Highly Expressed in Citrus Flowers Infected with the Fungus Colletotrichum acutatum, Causal Agent of Postbloom Fruit Drop

2003 ◽  
Vol 128 (4) ◽  
pp. 578-583 ◽  
Author(s):  
Wei Li ◽  
Rongcai Yuan ◽  
Jacqueline K. Burns ◽  
L.W. Timmer ◽  
Kuang-Ren Chung
Keyword(s):  
Sweet Orange ◽  
Acc Oxidase ◽  
Colletotrichum Acutatum ◽  
Cdna Clones ◽  
Gene Expressions ◽  
Cell Wall Modification ◽  
Young Fruit ◽  
Fruit Drop ◽  
Genes Encoding ◽  
Differential Gene

Colletotrichum acutatum J. H. Simmonds infects citrus flower petals, causing brownish lesions, young fruit drop, production of persistent calyces, and leaf distortion. This suggests that hormones may be involved in symptom development. To identify the types of hormones, cDNA clones encoding proteins related to ethylene and jasmonate (JA) biosynthesis, indole-3-acetic acid (IAA) regulation, cell-wall modification, signal transduction, or fruit ripening were used to examine differential gene expressions in calamondin (Citrus madurensis Lour) and/or `Valencia' sweet orange (Citrus sinensis Osbeck) after C. acutatum infection. Northern-blot analyses revealed that the genes encoding 1-aminocyclopropane-1-carboxylate (ACC) oxidase and 12-oxophytodienoate required for ethylene and JA biosynthesis, respectively, were highly up-regulated in both citrus species. Both gene transcripts increased markedly in petals, young fruit and stigmas, but not in calyces. The transcripts of the genes encoding IAA glucose transferase and auxin-responsive GH3-like protein, but not IAA amino acid hydrolyase, also markedly increased in both species 5 days after inoculation. The expansin and chitinase genes were slightly up-regulated, whereas the senescence-induced nuclease and ß-galactosidase genes were down-regulated in calamondin. No differential expression of transcripts was detected for the genes encoding expansin, polygalacturonase, and serine-threonine kinase in sweet orange. As compared to the water controls, infection of C. acutatum increased ethylene and IAA levels by 3- and 140-fold. In contrast, abscisic acid (ABA) levels were not significantly changed. Collectively, the results indicate that infection by C. acutatum of citrus flowers triggered differential gene expressions, mainly associated with IAA, ethylene, and JA production and regulation, and increased hormone concentrations, consistent with the hypothesis of the involvement of phytohormones in postbloom fruit drop.

Evaluation of fungicide applications to sweet orange at different flowering stages for control of postbloom fruit drop caused by Colletotrichum acutatum

2008 ◽  
Vol 27 (1) ◽  
pp. 71-76 ◽  
Author(s):  
A. de Goes ◽  
R.B.O. Garrido ◽  
R.F. Reis ◽  
R.B. Baldassari ◽  
M.A. Soares
Keyword(s):  
Sweet Orange ◽  
Colletotrichum Acutatum ◽  
Fruit Drop

scholarly journals Induction of Phytohormones and Differential Gene Expression in Citrus Flowers Infected by the Fungus Colletotrichum acutatum

2004 ◽  
Vol 17 (12) ◽  
pp. 1394-1401 ◽  
Author(s):  
Katherine A. Lahey ◽  
Rongcai Yuan ◽  
Jacqueline K. Burns ◽  
Peter P. Ueng ◽  
L. W. Timmer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Differential Gene Expression ◽  
Acc Oxidase ◽  
Acc Synthase ◽  
Colletotrichum Acutatum ◽  
Young Fruit ◽  
Fruit Drop ◽  
Significant Difference ◽  
Genes Encoding ◽  
Differential Gene

Colletotrichum acutatum infects citrus petals and induces premature fruit drop and the formation of persistent calyces. The accumulation of hormones and other growth regulators, and differential gene expression in affected flowers and young fruit, was examined following fungal infection. Ethylene evolution increased threefold and indole-3-acetic acid (IAA) accumulation was as much as 140 times. Abscisic acid (ABA) levels showed no significant response. After infection, both trans- and cis-12-oxo-phytodienoic acid increased 8- to 10-fold. No significant difference of trans-jasmonic acid (JA) was observed in citrus flower petals or pistils. However, a fivefold increase of cis-JA was detected. The amount of salicylic acid (SA) was elevated twofold in affected petals, but not in pistils. Northern blot analyses revealed that the genes encoding ACC oxidase or ACC synthase, and 12-oxo-phytodienoic acid (12-oxo-PDA) reductase, were highly expressed in affected flowers. The genes encoding auxin-related proteins also were upregulated. Application of 2-(4-chlorophenoxy)-2-methyl-propionic acid (clofibrate; a putative auxin inhibitor), 2,3,5-triiodobenzolic acid (an auxin transport inhibitor), or SA after inoculation significantly decreased the accumulation of the gene transcripts of auxin-responsive, GH3-like protein and 12-oxo-PDA reductase, but resulted in higher percentages of young fruit retention. The results indicate that imbalance of IAA, ethylene, and JA in C. acutatum-infected flowers may be involved in symptom development and young fruit drop.

scholarly journals Postbloom Fruit Drop of Citrus and Key Lime Anthracnose Are Caused by Distinct Phylogenetic Lineages of Colletotrichum acutatum

2008 ◽  
Vol 98 (3) ◽  
pp. 345-352 ◽  
Author(s):  
N. A. Peres ◽  
S. J. MacKenzie ◽  
T. L. Peever ◽  
L. W. Timmer
Keyword(s):  
Sweet Orange ◽  
Sequence Data ◽  
Geographic Area ◽  
The United States ◽  
Internal Transcribed Spacers ◽  
Colletotrichum Acutatum ◽  
Gene Encoding ◽  
Fruit Drop ◽  
Key Lime ◽  
Phylogenetic Lineages

Colletotrichum acutatum causes two diseases of citrus, postbloom fruit drop (PFD) and Key lime anthracnose (KLA). PFD is a disease restricted to flowers of sweet orange and most other citrus, and symptoms include petal necrosis, abscission of developing fruit, and the formation of persistent calyces. KLA is a disease of foliage, flowers, and fruits of Key lime only, and symptoms include necrotic lesions on leaves, fruits, twigs, flowers, and blight of entire shoots. The internal transcribed spacers 1 and 2 and the gene encoding the 5.8S ribosomal RNA subunit within the nuclear ribosomal cluster (ITS) and intron 2 of the glyceraldehyde-3-phosphate dehydrogenase gene (G3PD) were sequenced for isolates from PFD-affected sweet orange and KLA-affected Key limes collected in the United States (Florida), Brazil (São Paulo), Mexico, Belize, Costa Rica, and the Dominican Republic to determine if there are consistent genetic differences between PFD and KLA isolates over the geographic area where these diseases occur. Based on the sequence data, isolates clustered into two well-supported clades with little or no sequence variation among isolates within clades. One clade (PFD clade) contained PFD isolates from all countries sampled plus a few isolates from flowers of Key lime in Brazil. The other clade (KLA clade) contained KLA isolates from Key lime foliage from all countries sampled and one isolate from flowers of sweet orange in Mexico. In greenhouse inoculations with PFD and KLA isolates from Florida, isolates from both clades produced PFD symptoms on Orlando tangelo flowers, but KLA-clade isolates produced significantly less severe symptoms. PFD-clade isolates were not pathogenic to Key lime foliage, confirming previous studies. The differentiation of PFD and KLA isolates into two well-supported clades and the pathogenicity data indicate that PFD and KLA are caused by distinct phylogenetic lineages of C. acutatum that are also biologically distinct. PFD is a recently described disease (first reported in 1979) relative to KLA (first reported in 1912) and it had been proposed that strains causing PFD evolved from strains causing KLA eventually losing pathogenicity to Key lime foliage. We reject the hypothesis that PFD strains have diverged from KLA strains recently based on estimated divergence times of haplotypes and it appears that PFD and KLA strains have been dispersed throughout the Americas independently in association with each host.

Probenazole induces systemic acquired resistance in Arabidopsis with a novel type of action

2001 ◽  
Vol 25 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Keiko Yoshioka ◽  
Hideo Nakashita ◽  
Daniel F. Klessig ◽  
Isamu Yamaguchi
Keyword(s):  
Systemic Acquired Resistance ◽  
Acquired Resistance

scholarly journals Pre-harvest field application of enhanced freshness formulation reduces yield loss in orange

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Jaspa Samwel ◽  
Theodosy Msogoya ◽  
Abdul Kudra ◽  
Hosea Dunstan Mtui ◽  
Anna Baltazari ◽  
...  
Keyword(s):  
Yield Loss ◽  
Sweet Orange ◽  
New Technology ◽  
Significant Negative Correlation ◽  
Field Application ◽  
Yield Losses ◽  
Factorial Experiments ◽  
Marketable Yield ◽  
Pest Damage ◽  
Marketable Fruit

Abstract Background Orange (Citrus sinensis L.) production in Tanzania is constrained by several pre-harvest factors that include pests. Hexanal, sprayed as Enhanced Freshness Formulation (EFF) is a relatively new technology that has been reported to reduce pre-harvest loss in fruits. However, the effects of hexanal on pre-harvest yield loss of orange are not known. We studied the effects of hexanal as EFF on yield losses of three sweet orange cultivars namely, Early Valencia, Jaffa, and Late Valencia. Factorial experiments tested the effects of EFF concentration, variety, and time of EFF application on number of dropped fruit, percentage of non-marketable fruit and incidence of pest damage. Results Results showed significant negative correlation (p < 0.001) between EFF and the percentage of dropped fruit, non-marketable yield, and incidence of pest damage. An increase in hexanal concentration by 1%, is expected to reduce number of dropped fruit by 50, percentage of non-marketable by 35.6, and incidences of pest damage by 36.5% keeping other factors constant. Results also show significant association (p < 0.001) between time of hexanal application and non-marketable yield. Percentage of dropped fruit is expected to increase by 1 for each day away from harvest, keeping other factors constant. Conclusion Pre-harvest application of hexanal as EFF can significantly reduce number of dropped fruits, percentage of non-marketable fruit and incidence of pest damage.

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