Abstract:Imazapyr (IM) treatment applied at early reproductive developmental stages have been associated with induced male sterility in sunflower (Helianthus annuus L.). The aim of this work was to determine the effects induced by two different doses of IM-treatment (1X and 2X; 80 and 160 g a.i.•ha -1 ) on pollen grain yield, pollen viability and on the exine surface, in an intermediate resistant (I) and a completely resistant (R) genotype. An anatomical analysis of some stages during the microsporogenesis and microgam… Show more
“…However, the biological and molecular mechanisms involved in sunflower CIMS are still under study. Our previous reports have provided the first evidence of the gametocidal effect of imazapyr in resistant sunflower and have shown sporogenous tissue damage in both treated R and I genotypes (HA425 and 1058‐1 genotypes, respectively), but accelerated pollen development has been associated only with treated I plants (Ochogavía et al., 2020). We proposed a hypothetical mechanism in which AHAS inhibition induces amino acid starvation, leading to plastid destruction and autophagic cell death in microsporogenous tissue (Ochogavía et al., 2020).…”
Section: Discussionmentioning
confidence: 98%
“…Our previous reports have provided the first evidence of the gametocidal effect of imazapyr in resistant sunflower and have shown sporogenous tissue damage in both treated R and I genotypes (HA425 and 1058‐1 genotypes, respectively), but accelerated pollen development has been associated only with treated I plants (Ochogavía et al., 2020). We proposed a hypothetical mechanism in which AHAS inhibition induces amino acid starvation, leading to plastid destruction and autophagic cell death in microsporogenous tissue (Ochogavía et al., 2020). This mechanism has also been related to the cytocidal effects of sublethal doses of AHAS‐inhibiting herbicides in susceptible plants of rapeseed and Arabidopsis (Zhao et al., 2015; Liu et al., 2017).…”
Section: Discussionmentioning
confidence: 98%
“…Chemical induced male sterility is a valuable tool for timing optimization in hybrid crop breeding. In sunflower, imidazolinones have been proven to be promising AHAS‐inhibitory hybridization agents since the application of these herbicides such as imazethapyr or imazapyr during the early reproductive developmental stages induces male sterility in resistant sunflower lines (Sala & Bulos, 2012; Ochogavía et al., 2018, 2020). However, the biological and molecular mechanisms involved in sunflower CIMS are still under study.…”
Section: Discussionmentioning
confidence: 99%
“…This method, known as chemically induced male sterility (CIMS), represents a promising alternative that could allow breeders to test the combining ability of sunflower maintainer lines during early stages of development, to promote heterosis and outcrossing, with minimal prebreeding requirements. We have previously found that treatment of Imisun sunflower with the field recommended dose of imazapyr allows obtaining partial CIMS and that treated plants show a significant reduction of pollen yield and seed production, associated with pollen development alterations and sporogenous tissue damage (Ochogavía et al., 2018; 2020).…”
Section: Introductionmentioning
confidence: 99%
“…Based on all the above, the aim of this work was to characterize the molecular mechanisms of the CIMS system through imazapyr treatment during early reproductive stages in two Imisun sunflower lines: a completely resistant, HA425, and an intermediate resistant line, 1058‐1 (Bruniard & Miller, 2001; Miller & Al‐Khatib, 2002). The comparative transcript profiling analysis between treated and control plants was achieved by complementary DNA amplified fragment‐length polymorphism (cDNA‐AFLP) on the three most informative dates during the development of the sporogenous tissue (Ochogavía et al., 2018; 2020). To confirm the cytocidal effect of the treatment at physiological and anatomical levels, the pollen physiology was evaluated and the development of the sporogenous tissue was analyzed by Differential Interference Contrast (DIC) microscopy.…”
Chemically induced male sterility (CIMS) is a valuable tool for hybrid breeding in crops. In this context, the acetohydroxyacid synthase (AHAS)‐inhibiting imazapyr has been proposed to induce male sterility in Imisun sunflower (Helianthus annuus L.) when applied during early reproductive development in a two‐fold higher than recommended field dose. This study aimed to perform a comparative transcriptomic analysis to find out the molecular bases of the gametocidal effect of imazapyr on two Imisun genotypes differing in their herbicide resistance level: completely resistant and intermediate resistant. The CIMS of treated plants was confirmed at physiological and anatomical levels. A total of 948 differentially expressed transcript‐derived fragments (TDFs) were identified by complementary DNA amplified fragment‐length polymorphism (cDNA‐AFLP) analysis at the three most informative developmental stages of anther development. Several genes related to xenobiotic metabolism and stress, including cytochrome P450 monooxygenases and ATP‐binding cassette transporters, were identified in the completely resistant genotype. Interestingly, a group of genes, including protein kinases, sulfonylurea receptor 1, aspartic signal peptide‐peptidase, and specific membrane transporters, were recognized from the differential TDFs simultaneously detected in both genotypes. Some of these transcripts were validated by quantitative real‐time polymerase chain reaction (qPCR) in both genotypes. Therefore, these transcripts could be exclusively related to the CIMS in sunflower. Based on the results, we suggest a probable model of action for the gametocidal effect of imazapyr. Our research provides new insights into the molecular mechanisms of male sterility induction in sunflower.
“…However, the biological and molecular mechanisms involved in sunflower CIMS are still under study. Our previous reports have provided the first evidence of the gametocidal effect of imazapyr in resistant sunflower and have shown sporogenous tissue damage in both treated R and I genotypes (HA425 and 1058‐1 genotypes, respectively), but accelerated pollen development has been associated only with treated I plants (Ochogavía et al., 2020). We proposed a hypothetical mechanism in which AHAS inhibition induces amino acid starvation, leading to plastid destruction and autophagic cell death in microsporogenous tissue (Ochogavía et al., 2020).…”
Section: Discussionmentioning
confidence: 98%
“…Our previous reports have provided the first evidence of the gametocidal effect of imazapyr in resistant sunflower and have shown sporogenous tissue damage in both treated R and I genotypes (HA425 and 1058‐1 genotypes, respectively), but accelerated pollen development has been associated only with treated I plants (Ochogavía et al., 2020). We proposed a hypothetical mechanism in which AHAS inhibition induces amino acid starvation, leading to plastid destruction and autophagic cell death in microsporogenous tissue (Ochogavía et al., 2020). This mechanism has also been related to the cytocidal effects of sublethal doses of AHAS‐inhibiting herbicides in susceptible plants of rapeseed and Arabidopsis (Zhao et al., 2015; Liu et al., 2017).…”
Section: Discussionmentioning
confidence: 98%
“…Chemical induced male sterility is a valuable tool for timing optimization in hybrid crop breeding. In sunflower, imidazolinones have been proven to be promising AHAS‐inhibitory hybridization agents since the application of these herbicides such as imazethapyr or imazapyr during the early reproductive developmental stages induces male sterility in resistant sunflower lines (Sala & Bulos, 2012; Ochogavía et al., 2018, 2020). However, the biological and molecular mechanisms involved in sunflower CIMS are still under study.…”
Section: Discussionmentioning
confidence: 99%
“…This method, known as chemically induced male sterility (CIMS), represents a promising alternative that could allow breeders to test the combining ability of sunflower maintainer lines during early stages of development, to promote heterosis and outcrossing, with minimal prebreeding requirements. We have previously found that treatment of Imisun sunflower with the field recommended dose of imazapyr allows obtaining partial CIMS and that treated plants show a significant reduction of pollen yield and seed production, associated with pollen development alterations and sporogenous tissue damage (Ochogavía et al., 2018; 2020).…”
Section: Introductionmentioning
confidence: 99%
“…Based on all the above, the aim of this work was to characterize the molecular mechanisms of the CIMS system through imazapyr treatment during early reproductive stages in two Imisun sunflower lines: a completely resistant, HA425, and an intermediate resistant line, 1058‐1 (Bruniard & Miller, 2001; Miller & Al‐Khatib, 2002). The comparative transcript profiling analysis between treated and control plants was achieved by complementary DNA amplified fragment‐length polymorphism (cDNA‐AFLP) on the three most informative dates during the development of the sporogenous tissue (Ochogavía et al., 2018; 2020). To confirm the cytocidal effect of the treatment at physiological and anatomical levels, the pollen physiology was evaluated and the development of the sporogenous tissue was analyzed by Differential Interference Contrast (DIC) microscopy.…”
Chemically induced male sterility (CIMS) is a valuable tool for hybrid breeding in crops. In this context, the acetohydroxyacid synthase (AHAS)‐inhibiting imazapyr has been proposed to induce male sterility in Imisun sunflower (Helianthus annuus L.) when applied during early reproductive development in a two‐fold higher than recommended field dose. This study aimed to perform a comparative transcriptomic analysis to find out the molecular bases of the gametocidal effect of imazapyr on two Imisun genotypes differing in their herbicide resistance level: completely resistant and intermediate resistant. The CIMS of treated plants was confirmed at physiological and anatomical levels. A total of 948 differentially expressed transcript‐derived fragments (TDFs) were identified by complementary DNA amplified fragment‐length polymorphism (cDNA‐AFLP) analysis at the three most informative developmental stages of anther development. Several genes related to xenobiotic metabolism and stress, including cytochrome P450 monooxygenases and ATP‐binding cassette transporters, were identified in the completely resistant genotype. Interestingly, a group of genes, including protein kinases, sulfonylurea receptor 1, aspartic signal peptide‐peptidase, and specific membrane transporters, were recognized from the differential TDFs simultaneously detected in both genotypes. Some of these transcripts were validated by quantitative real‐time polymerase chain reaction (qPCR) in both genotypes. Therefore, these transcripts could be exclusively related to the CIMS in sunflower. Based on the results, we suggest a probable model of action for the gametocidal effect of imazapyr. Our research provides new insights into the molecular mechanisms of male sterility induction in sunflower.
Prunus serotina Ehrh. is an alien invasive neophyte widespread in European forests. So far, no effective methods of its elimination have been developed. For this reason, the aim of our study was to determine how herbicides affect the morphological characteristics of pollen grains. This knowledge may be crucial to control this invasive species. The current study was carried out in a research area of 2.7 ha located in the Zielonka Forest near Poznań, Poland (N 52°31′58.016″, E 17°05′55.588″). We tested morphological differences among ten features of P. serotina pollen, based on the samples collected from 15 control trees compared to the 50 trees treated with five different herbicides. In total 1950 pollen grains were measured. We confirmed the adopted hypotheses of long-term herbicide influence on P. serotina pollen. Pollen grains from the control trees had a longer equatorial axis, were more elongated in shape and had the largest range of exine thickness compared to the pollen from the herbicide-treated samples. Exine thickness in the control sample was on average 0.74 µm, ranging from 0.42 to 1.19 µm. The average values and the ranges of this trait in the samples treated with herbicides were larger (e.g. average exine thickness was from 0.90 to 0.95 µm). There were differences in the P/E ranges of variability between the control and herbicide-treated samples. In the control sample the P/E ratio was 1.32–2.04 and elongated forms of pollen shapes prevailed, while in the herbicide-treated samples it ranged from 1.03 to 1.47. The share of deformed pollen grains in the herbicide-treated samples was lower than expected, ranging from 8.7 to 25.3%, while in the control samples it was 6%. Logo and Mustang turned out to be the most effective among the herbicides used in the described research. The two used application methods were found to have an effect on pollen quality.
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