Glyphosate-induced anther indehiscence in cotton is partially temperature dependent and involves cytoskeleton and secondary wall modifications and auxin accumulation.
Yield reduction caused by late application of glyphosate to glyphosate-resistant cotton (Gossypium hirsutum; GRC) expressing CP4 5-enol-pyruvylshikmate-3-P synthase under the cauliflower mosaic virus-35S promoter has been attributed to male sterility. This study was aimed to elucidate the factors and mechanisms involved in this phenomenon. Western and tissue-print blots demonstrated a reduced expression of the transgene in anthers of GRC compared to ovules of the same plants. Glyphosate application to GRC grown at a high temperature regime after the initiation of flower buds caused a complete loss of pollen viability and inhibition of anther dehiscence, while at a moderate temperature regime only 50% of the pollen grains were disrupted and anther dehiscence was normal. Glyphosate-damaged anthers exhibited a change in the deposition of the secondary cell wall thickenings (SWT) in the endothecium cells, from the normal longitudinal orientation to a transverse orientation, and hindered septum disintegration. These changes occurred only at the high temperature regime. The reorientation of SWT in GRC was accompanied by a similar change in microtubule orientation. A similar reorientation of microtubules was also observed in Arabidopsis (Arabidopsis thaliana) seedlings expressing green fluorescent protein tubulin (tubulin alpha 6) following glyphosate treatment. Glyphosate treatment induced the accumulation of high levels of indole-3-acetic acid in GRC anthers. Cotton plants treated with 2,4-dichlorophenoxyacetic acid had male sterile flowers, with SWT abnormalities in the endothecium layer similar to those observed in glyphosate-treated plants. Our data demonstrate that glyphosate inhibits anther dehiscence by inducing changes in the microtubule and cell wall organization in the endothecium cells, which are mediated by auxin.
Yasuor
Hagai
H
R.H. Smith Institute of Plant Sciences and Genetics in Agriculture, Faculty of Agricultural, Food, and Environmental Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel. yasuor@agri.huji.ac.il
Abu-Abied
Mohamad
M
Belausov
Eduard
E
Madmony
Anat
A
Sadot
Einat
E
Riov
Joseph
J
Rubin
Baruch
B
D015084:2,4-Dichlorophenoxyacetic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D017796:Caulimovirus / Q000235:genetics; D002473:Cell Wall / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D035264:Flowers / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003368:Gossypium / Q000033:anatomy & histology / Q000187:drug effects* / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000032:analysis; D007210:Indoleacetic Acids / Q000378:metabolism*; D051479:Plant Infertility / Q000502:physiology; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D011058:Pollen / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012098:Reproduction / Q000187:drug effects; D012231:Rhizobium / Q000235:genetics; D013696:Temperature; D014404:Tubulin / Q000032:analysis / Q000378:metabolism; D000097797:Glyphosate
D015084:2,4-Dichlorophenoxyacetic Acid; D001426:Bacterial Proteins; D005998:Glycine; D049452:Green Fluorescent Proteins; D007210:Indoleacetic Acids; D011993:Recombinant Fusion Proteins; D014404:Tubulin; D000097797:Glyphosate