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הספר "אוצר וולקני"
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קהילה:
אסיף מאגר המחקר החקלאי
פותח על ידי קלירמאש פתרונות בע"מ -
לימוד הבקרה של גנים המעורבים בנשירת פרחים ועלים בצמחי עגבנייה (Lycopersicon esculentum Mill.).‏
שנה:
2010
מקור הפרסום :
הפקולטה לחקלאות
מחברים :
סונדארסאן, סריוויגנש
;
.
כרך :
מחברים נוספים:
מנחים :
מאיר, שמעון
;
.
מעמוד:
0
עד עמוד:
0
(
סהכ עמודים:
1
)
תקציר:

supervision by: Meir Shimon, Riov Joseph

Abscission, the separation of organs from the parent plant, results in pre-harvest and postharvest losses of quality and longevity in many fresh produce. To overcome this problem, many crops are treated after harvest with various chemicals to delay or prevent abscission. The abscission process is initiated by changes in the auxin gradient across the abscission zone (AZ), is triggered by ethylene, and may be accelerated by postharvest stresses. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the molecular and biochemical basis of the increased AZ sensitivity to ethylene. The molecular mechanisms that drive the acquisition of abscission competence and its modulation by auxin gradients are still unknown. Organ abscission is accompanied by a modified expression of various types of genes, including ethylene-inducible, auxin-responsive, pathogen-related (PR) genes, as well as genes encoding for cell-wall degrading enzymes. Our study used leaf and flower AZs of tomato (Solanum lycopersicum Mill, cvs. 'Shiran 1335' and 'VF-36') as a model system, to examine the spatial and temporal expression pattern of the genes, which control molecular mechanisms regulating the abscission process, in the flower AZ (FAZ) and in the leaf AZ (LAZ). We examined, using semi-quantitative (sq) and quantitative (q) PCR, transcriptome changes in tomato flower and leaf AZs during the acquisition of ethylene sensitivity following flower removal or leaf deblading, which deplete the AZs from auxin. In addition, we have followed pedicel or petiole abscission induced by flower removal or leaf deblading, respectively. We have studied changes in gene expression in the tomato FAZ and LAZ, as compared to flower non-AZ (FNAZ) and leaf non-AZ (LNAZ), during 0, 2, 4, 8, and 14 h after flower removal or during 0, 12, 24, 48, and 72 h after leaf deblading. In addition, we examined the expression the various genes in other plant tissues, such as young and mature shoots, young and mature leaves and roots. Based on these expression studies, we selected some genes for stable transformation into tomato plants. For this purpose, the RNAi (hpRNA) vectors, PGSA 1285 and pHANNIBAL, driven by the CaMV 35S constitutive promoter or by the isolated tissue-specific TAPG4 promoter, were used to silence the selected genes for their further functional analysis. The present study was performed according to the following stages: 1) We have validated the microarray (Affymetrix Tomato GeneChip) transcriptome results in the FAZ and FNAZ by means of sq-PCR and qPCR. The genes encoding for abscission related cell-wall hydrolases, TAPG1, TAPG2, TAPG4, Cel1, XET-BR1, were examined in order to validate the abscission system. The genes which were highly regulated shortly (within 2 h) after flower removal were also selected, including ethylene signal transduction-related genes - ERF2, ERF1c, ERT10, JERF3; regulatory genes – Protein phosphatase-like; early-modified transcription factors (TFs) - MybSt1; novel AZ-specific genes - PHANTASTICA, TAGL12 (MADS-box), Knotted protein - TKN4, OVATE, KD1, and TPRP-F1. The results of the sq-PCR and qPCR analyses were in full agreement with the microarray results except for MybSt1. This shows that the microarray results truly reflect the events occurring in the FAZ and FNAZ. 2) The above-mentioned genes showed different kinetics of expression levels in the LAZ and LNAZ following leaf deblading, as well as in the other plant tissues examined to study their tissue specificity. 3) We have studied the kinetics of petiole abscission in response to leaf deblading (auxin removal) and exogenous ethylene. The results indicate that ethylene was effective in inducing petiole abscission only in debladed plants. 4) We identified potential candidate genes from the validated genes tested above, that might regulate abscission of tomato flowers or leaves for their detailed functional analysis by silencing their expression by means of RNA interference-based gene silencing (RNAi) in transgenic tomato plants. The selection was based on genes, which were specifically and significantly up- or down-regulated in the FAZ within 2 h after flower removal, or in the LAZ within 24 h after leaf deblading. 5) We have used the RNAi (hpRNA) vectors, PGSA 1285 and pHANNIBAL, driven by the CAMV 35S promoter, to silence the following six selected genes in the entire plant system for studying their functional role: ERF2, Protein phosphatase-like, JERF3, and TKN4, Proline-rich protein (TPRP-F1), and KD1. These genes are currently in the stage of transforming into plants (Phase V), and their modified phenotypes will be examined within few months. 6) We have isolated the TAPG4 promoter from the genomic DNA and cloned it into the pGEMT vector by modifying the restriction sites to suit our vectors. We assembled the RNAi constructs, driven by TAPG4 as a promoter, to induce tissue-specific silencing in the FAZ, rather than silencing the entire plant system by using the constitutive CaMV 35S promoter. The constructs for two genes, JERF3 and TKN4, with the TAPG4 promoter, are ready, they are currently at Phase V. Similar constructs for TPRP-F1, and KD1 genes are in Phase IV. Hence, we expect to see phenotypes within in a few months. The findings of this study will shed light on the molecular mechanisms that drive the acquisition of abscission competence, and will facilitate novel approaches to the control and manipulation of abscission in horticultural and agricultural crops, in order to improve their postharvest quality.

הערות:
הגישה לטקסט מלא – למשתמש מורשה בלבד
flower
Genes
leaf abscission
Lycopersicon esculentum Mill
tomato
נשירה
עוד תגיות
תוכן קשור
פרטים נוספים
מזהה עצם דיגיטלי :
מס' מאמר:
0
שיוך:
מאגר מידע:
סוג חומר:
דיסרטציה
;
.
שפה:
אנגלית
הערות לעורכים:
מזהה:
43311
עודכן לאחרונה:
02/03/2022 17:27
תאריך יצירה:
25/08/2019 09:24
אולי יעניין אותך גם
פרסום מדעי
לימוד הבקרה של גנים המעורבים בנשירת פרחים ועלים בצמחי עגבנייה (Lycopersicon esculentum Mill.).‏

supervision by: Meir Shimon, Riov Joseph

Abscission, the separation of organs from the parent plant, results in pre-harvest and postharvest losses of quality and longevity in many fresh produce. To overcome this problem, many crops are treated after harvest with various chemicals to delay or prevent abscission. The abscission process is initiated by changes in the auxin gradient across the abscission zone (AZ), is triggered by ethylene, and may be accelerated by postharvest stresses. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the molecular and biochemical basis of the increased AZ sensitivity to ethylene. The molecular mechanisms that drive the acquisition of abscission competence and its modulation by auxin gradients are still unknown. Organ abscission is accompanied by a modified expression of various types of genes, including ethylene-inducible, auxin-responsive, pathogen-related (PR) genes, as well as genes encoding for cell-wall degrading enzymes. Our study used leaf and flower AZs of tomato (Solanum lycopersicum Mill, cvs. 'Shiran 1335' and 'VF-36') as a model system, to examine the spatial and temporal expression pattern of the genes, which control molecular mechanisms regulating the abscission process, in the flower AZ (FAZ) and in the leaf AZ (LAZ). We examined, using semi-quantitative (sq) and quantitative (q) PCR, transcriptome changes in tomato flower and leaf AZs during the acquisition of ethylene sensitivity following flower removal or leaf deblading, which deplete the AZs from auxin. In addition, we have followed pedicel or petiole abscission induced by flower removal or leaf deblading, respectively. We have studied changes in gene expression in the tomato FAZ and LAZ, as compared to flower non-AZ (FNAZ) and leaf non-AZ (LNAZ), during 0, 2, 4, 8, and 14 h after flower removal or during 0, 12, 24, 48, and 72 h after leaf deblading. In addition, we examined the expression the various genes in other plant tissues, such as young and mature shoots, young and mature leaves and roots. Based on these expression studies, we selected some genes for stable transformation into tomato plants. For this purpose, the RNAi (hpRNA) vectors, PGSA 1285 and pHANNIBAL, driven by the CaMV 35S constitutive promoter or by the isolated tissue-specific TAPG4 promoter, were used to silence the selected genes for their further functional analysis. The present study was performed according to the following stages: 1) We have validated the microarray (Affymetrix Tomato GeneChip) transcriptome results in the FAZ and FNAZ by means of sq-PCR and qPCR. The genes encoding for abscission related cell-wall hydrolases, TAPG1, TAPG2, TAPG4, Cel1, XET-BR1, were examined in order to validate the abscission system. The genes which were highly regulated shortly (within 2 h) after flower removal were also selected, including ethylene signal transduction-related genes - ERF2, ERF1c, ERT10, JERF3; regulatory genes – Protein phosphatase-like; early-modified transcription factors (TFs) - MybSt1; novel AZ-specific genes - PHANTASTICA, TAGL12 (MADS-box), Knotted protein - TKN4, OVATE, KD1, and TPRP-F1. The results of the sq-PCR and qPCR analyses were in full agreement with the microarray results except for MybSt1. This shows that the microarray results truly reflect the events occurring in the FAZ and FNAZ. 2) The above-mentioned genes showed different kinetics of expression levels in the LAZ and LNAZ following leaf deblading, as well as in the other plant tissues examined to study their tissue specificity. 3) We have studied the kinetics of petiole abscission in response to leaf deblading (auxin removal) and exogenous ethylene. The results indicate that ethylene was effective in inducing petiole abscission only in debladed plants. 4) We identified potential candidate genes from the validated genes tested above, that might regulate abscission of tomato flowers or leaves for their detailed functional analysis by silencing their expression by means of RNA interference-based gene silencing (RNAi) in transgenic tomato plants. The selection was based on genes, which were specifically and significantly up- or down-regulated in the FAZ within 2 h after flower removal, or in the LAZ within 24 h after leaf deblading. 5) We have used the RNAi (hpRNA) vectors, PGSA 1285 and pHANNIBAL, driven by the CAMV 35S promoter, to silence the following six selected genes in the entire plant system for studying their functional role: ERF2, Protein phosphatase-like, JERF3, and TKN4, Proline-rich protein (TPRP-F1), and KD1. These genes are currently in the stage of transforming into plants (Phase V), and their modified phenotypes will be examined within few months. 6) We have isolated the TAPG4 promoter from the genomic DNA and cloned it into the pGEMT vector by modifying the restriction sites to suit our vectors. We assembled the RNAi constructs, driven by TAPG4 as a promoter, to induce tissue-specific silencing in the FAZ, rather than silencing the entire plant system by using the constitutive CaMV 35S promoter. The constructs for two genes, JERF3 and TKN4, with the TAPG4 promoter, are ready, they are currently at Phase V. Similar constructs for TPRP-F1, and KD1 genes are in Phase IV. Hence, we expect to see phenotypes within in a few months. The findings of this study will shed light on the molecular mechanisms that drive the acquisition of abscission competence, and will facilitate novel approaches to the control and manipulation of abscission in horticultural and agricultural crops, in order to improve their postharvest quality.

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