Tapetal development and abiotic stress: a centre of vulnerability

2012 ◽  
Vol 39 (7) ◽  
pp. 553 ◽  
Author(s):  
Roger W. Parish ◽  
Huy A. Phan ◽  
Sylvana Iacuone ◽  
Song F. Li
Keyword(s):  
Cell Wall ◽  
Abiotic Stress ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Pollen Abortion ◽  
Cell Wall Invertase ◽  
Developmental Program ◽  
Specific Effects ◽  
Hexose Sugars ◽  
Microspore Stage

Many self-fertilising crops are particularly sensitive to abiotic stress at the reproductive stage. In rice (Oryza sativa L.) and wheat (Triticum aestivum L.), for example, abiotic stress during meiosis and the young microspore stage indicates the tapetum is highly vulnerable and that the developmental program appears to be compromised. Tapetal hypertrophy can occur as a consequence of cold and drought stress, and programmed cell death (PCD) is delayed or inhibited. Since the correct timing of tapetal PCD is essential for pollen reproduction, substantial losses in grain yield occur. In wheat and rice, a decrease in tapetal cell wall invertase levels is correlated with pollen abortion and results in the amount of hexose sugars reaching the tapetum, and subsequently the developing microspores, being severely reduced (‘starvation hypothesis’). ABA and gibberellin levels may be modified by cold and drought, influencing levels of cell wall invertase(s) and the tapetal developmental program, respectively. Many genes regulating tapetal and microspore development have been identified in Arabidopsis thaliana (L.) Heynh. and rice and the specific effects of abiotic stresses on the program and pathways can now begin to be assessed.

scholarly journals The Major Factors Causing the Microspore Abortion of Genic Male Sterile Mutant NWMS1 in Wheat (Triticum aestivum L.)

2019 ◽  
Vol 20 (24) ◽  
pp. 6252 ◽  
Author(s):  
Junchang Li ◽  
Jing Zhang ◽  
Huijuan Li ◽  
Hao Niu ◽  
Qiaoqiao Xu ◽  
...  
Keyword(s):  
Triticum Aestivum ◽  
Male Sterility ◽  
Genetic Research ◽  
Triticum Aestivum L ◽  
Anther Development ◽  
Sucrose Metabolism ◽  
Male Sterile ◽  
Pollen Abortion ◽  
Microspore Stage ◽  
Regulation Model

Male sterility is a valuable trait for genetic research and production application of wheat (Triticum aestivum L.). NWMS1, a novel typical genic male sterility mutant, was obtained from Shengnong 1, mutagenized with ethyl methane sulfonate (EMS). Microstructure and ultrastructure observations of the anthers and microspores indicated that the pollen abortion of NWMS1 started at the early uninucleate microspore stage. Pollen grain collapse, plasmolysis, and absent starch grains were the three typical characteristics of the abnormal microspores. The anther transcriptomes of NWMS1 and its wild type Shengnong 1 were compared at the early anther development stage, pollen mother cell meiotic stage, and binucleate microspore stage. Several biological pathways clearly involved in abnormal anther development were identified, including protein processing in endoplasmic reticulum, starch and sucrose metabolism, lipid metabolism, and plant hormone signal transduction. There were 20 key genes involved in the abnormal anther development, screened out by weighted gene co-expression network analysis (WGCNA), including SKP1B, BIP5, KCS11, ADH3, BGLU6, and TIFY10B. The results indicated that the defect in starch and sucrose metabolism was the most important factor causing male sterility in NWMS1. Based on the experimental data, a primary molecular regulation model of abnormal anther and pollen developments in mutant NWMS1 was established. These results laid a solid foundation for further research on the molecular mechanism of wheat male sterility.

Molecular cloning and expression analysis of the cell-wall invertase gene family in rice (Oryza sativa L.)

2005 ◽  
Vol 24 (4) ◽  
pp. 225-236 ◽  
Author(s):  
Jung-Il Cho ◽  
Sang-Kyu Lee ◽  
Seho Ko ◽  
He-Kyung Kim ◽  
Sung-Hoon Jun ◽  
...  
Keyword(s):  
Cell Wall ◽  
Oryza Sativa ◽  
Gene Family ◽  
Molecular Cloning ◽  
Expression Analysis ◽  
Oryza Sativa L ◽  
Cloning And Expression ◽  
Cell Wall Invertase ◽  
Invertase Gene

Study of the Changes in Insoluble Polysaccharides during Pollen Development in Rice (Oryza sativa L.) by Microscopic Multispectral Imaging

2010 ◽  
Vol 16 (4) ◽  
pp. 488-501 ◽  
Author(s):  
Shunan Liu ◽  
Lei Pan ◽  
Qiongshui Wu ◽  
Yaojun Hu ◽  
Xiaojun Chen ◽  
...  
Keyword(s):  
Pollen Development ◽  
Multispectral Imaging ◽  
Oryza Sativa L ◽  
Periodic Acid ◽  
Pollen Abortion ◽  
Periodic Acid Schiff ◽  
Steep Decrease ◽  
Multispectral Analysis ◽  
Microspore Stage ◽  
Insoluble Polysaccharides

AbstractMultispectral analysis combined with the Periodic Acid-Schiff method was used to investigate cytological features of insoluble polysaccharides and changes in total insoluble polysaccharide content (TPC) during pollen development in rice, including four cytoplasmic male sterility lines (MSLs) and their corresponding fertility-maintaining lines (FMLs). The multispectral curves of the relative transmittance value (RTV) and the images of developing pollen cells were obtained across a range of successive wavelengths (400–720 nm). A minimum RTV was found near 550 nm indicating an absorption peak of the TPC. Thus, the TPC was measured using the RTV of 550 nm. In the four FMLs, the minimum TPC of developing pollen cells occurred at the late microspore stage, while the maximum TPC occurred at the mature pollen grain stage. The TPC levels of pollen cells were significantly higher in the four FMLs than in their corresponding MSLs during and after pollen abortion. Notably, a steep decrease of multispectral curves at 420 nm appeared before the occurrence of abortion, implying a marker associated with pollen abortion in rice. Our results will be helpful for exploring the changes in TPC during pollen ontogenesis in rice and provide a novel method for the study of bio-macromolecules.

scholarly journals Genome-level identification of cell wall invertase genes in wheat for the study of drought tolerance

2012 ◽  
Vol 39 (7) ◽  
pp. 569 ◽  
Author(s):  
Hollie Webster ◽  
Gabriel Keeble ◽  
Bernard Dell ◽  
John Fosu-Nyarko ◽  
Y. Mukai ◽  
...  
Keyword(s):  
Cell Wall ◽  
Drought Tolerance ◽  
Aegilops Tauschii ◽  
Sequence Divergence ◽  
Wheat Chromosome ◽  
Triticum Aestivum L ◽  
Pollen Sterility ◽  
Cell Wall Invertase ◽  
D Genome ◽  
Specific Expression

In wheat (Triticum aestivum L.) drought-induced pollen sterility is a major contributor to grain yield loss and is caused by the downregulation of the cell wall invertase gene IVR1. The IVR1 gene catalyses the irreversible hydrolysis of sucrose to glucose and fructose, the essential energy substrates which support pollen development. Downregulation of IVR1 in response to drought is isoform specific and shows variation in temporal and tissue-specific expression. IVR1 is now prompting interest as a candidate gene for molecular marker development to screen wheat germplasm for improved drought tolerance. The aim of this study was to define the family of IVR1 genes to enable: (1) individual isoforms to be assayed in gene expression studies; and (2) greater accuracy in IVR1 mapping to the wheat genetic map and drought tolerance QTL analysis. Using a cell wall invertase-specific motif as a probe, wheat genomics platforms were screened for the presence of unidentified IVR1 isoforms. Wheat genomics platforms screened included the IWGSC wheat survey sequence, the wheat D genome donor sequence from Aegilops tauschii Coss, and the CCG wheat chromosome 3B assembly: contig506. Chromosome-specific sequences homologous to the query motif were isolated and characterised. Sequence annotation results showed five previously unidentified IVR1 isoforms exist on multiple chromosome arms and on all three genomes (A, B and D): IVR1–3A, IVR1–4A, IVR1–5B, IVR1.2–3B and IVR1-5D. Including three previously characterised IVR1 isoforms (IVR1.1–1A, IVR1.2–1A and IVR1.1–3B), the total number of isoform gene family members is eight. The IVR1 isoforms contain two motifs common to cell wall invertase (NDPN and WECPDF) and a high degree of conservation in exon 4, suggesting conservation of functionality. Sequence divergence at a primary structure level in other regions of the gene was evident amongst the isoforms, which likely contributes to variation in gene regulation and expression in response to water deficit within this subfamily of IVR1 isoforms in wheat.

Structural and functional analyses of the wheat genomes based on expressed sequence tags (ESTs) related to abiotic stresses

Genome ◽  
2006 ◽  
Vol 49 (10) ◽  
pp. 1324-1340 ◽  
Author(s):  
J. Ramalingam ◽  
M.S. Pathan ◽  
O. Feril ◽  
Miftahudin ◽  
K. Ross ◽  
...  
Keyword(s):  
Abiotic Stress ◽  
Oryza Sativa L ◽  
Triticum Aestivum L ◽  
Binding Activity ◽  
Homoeologous Chromosome ◽  
D Genome ◽  
B Genome ◽  
Group 4 ◽  
Group 2 ◽  
And Function

To gain insights into the structure and function of the wheat (Triticum aestivum L.) genomes, we identified 278 ESTs related to abiotic stress (cold, heat, drought, salinity, and aluminum) from 7671 ESTs previously mapped to wheat chromosomes. Of the 278 abiotic stress related ESTs, 259 (811 loci) were assigned to chromosome deletion bins and analyzed for their distribution pattern among the 7 homoeologous chromosome groups. Distribution of abiotic stress related EST loci were not uniform throughout the different regions of the chromosomes of the 3 wheat genomes. Both the short and long arms of group 4 chromosomes showed a higher number of loci in their distal regions compared with proximal regions. Of the 811 loci, the number of mapped loci on the A, B, and D genomes were 258, 281, and 272, respectively. The highest number of abiotic stress related loci were found in homoeologous chromosome group 2 (142 loci) and the lowest number were found in group 6 (94 loci). When considering the genome-specific ESTs, the B genome showed the highest number of unique ESTs (7 loci), while none were found in the D genome. Similarly, considering homoeologous group-specific ESTs, group 2 showed the highest number with 16 unique ESTs (58 loci), followed by group 4 with 9 unique ESTs (33 loci). Many of the classified proteins fell into the biological process categories associated with metabolism, cell growth, and cell maintenance. Most of the mapped ESTs fell into the category of enzyme activity (28%), followed by binding activity (27%). Enzymes related to abiotic stress such as β-galactosidase, peroxidase, glutathione reductase, and trehalose-6-phosphate synthase were identified. The comparison of stress-responsive ESTs with genomic sequences of rice (Oryza sativa L.) chromosomes revealed the complexities of colinearity. This bin map provides insight into the structural and functional details of wheat genomic regions in relation to abiotic stress.

Cereal Callus Cultures: Control of Headspace Gases Can Optimise the Conditions for Callus Proliferation

1992 ◽  
Vol 40 (6) ◽  
pp. 737 ◽  
Author(s):  
SW Adkins
Keyword(s):  
Oryza Sativa L ◽  
Petri Dish ◽  
Triticum Aestivum L ◽  
Callus Cultures ◽  
Gaseous Atmosphere ◽  
Callus Growth ◽  
Culture Vessel ◽  
Rice Callus ◽  
Incubation Temperatures ◽  
Wheat Callus

The protective conditions under which callus cultures are grown to prevent microbial contamination and to reduce tissue desiccation cause the accumulation of volatiles in the vessel headspace and reduce the availability of oxygen for respiration. To demonstrate the importance of the gaseous atmosphere to culture growth a study was undertaken on non-morphogenic rice and wheat callus incubated under a number of environmental conditions. Changes in the gaseous atmosphere above rice (Oryza sativa L.) callus during routine culture in a petri dish suppressed growth and promoted necrosis. Incubating callus under a continuous flow of gas mixtures of known composition suggested that the inhibition of growth was caused by the accumulation of high levels of ethylene and to the rapid depletion of oxygen. In order to evaluate the importance of ethylene accumulation aminoethoxyvinyl glycine (AVG), I-aminocyclopropane-I-carboxylic acid (ACC) and silver nitrate (AgNO3) were added to the nutrient medium and ethylene was measured during callus culture. Ethylene restricted callus growth particularly under high (35°C) compared with moderate (25°C) incubation temperatures and under illuminated compared with dark incubation. Under illuminated incubation at 25°C, AVG ( 5 μM ) and AgNO3 (50 μM) improved rice callus growth by 69 and 54% respectively while ACC (100 μM) decreased growth by 15%. Furthermore, rice callus growth was better in large compared with small culture vessels since ethylene accumulation was reduced. In contrast, wheat (Triticum aestivum L.) callus grew well in the petri dish system and released very little ethylene into the culture vessel headspace. Growth was better under illuminated than darkened conditions and under moderate (25°C) compared with high (35°C) incubation temperatures. Furthermore, wheat callus growth was only marginally better in large compared with small culture vessels. Ethylene was not a restrictive factor of wheat callus growth since only low levels were detected in all conditions of incubation. Better control of ethylene and increased oxygen availability could be a way of increasing cell and tissue production for genetic engineering studies of otherwise recalcitrant species such as rice, and may be a way of improving manipulation of wheat.

Actin has multiple roles in the formation and architecture of zoospores of the oomycetes, Saprolegnia ferax and Achlya bisexualis

1992 ◽  
Vol 102 (3) ◽  
pp. 611-627 ◽  
Author(s):  
I. BRENT HEATH ◽  
RUTH L. HAROLD
Keyword(s):  
Cell Wall ◽  
Germ Tube ◽  
Multiple Roles ◽  
Rhodamine Phalloidin ◽  
Saprolegnia Ferax ◽  
Functional Changes ◽  
Specific Effects ◽  
Changing Patterns ◽  
Microtubular Root ◽  
Achlya Bisexualis

Very similar changing patterns of actin are described with rhodamine-phalloidin labelling during the zoosporic life cycle of the oomycetes, Saprolegnia ferax and Achlya bisexualis. By comparing the changes with previously described ultrastructural and functional changes, we show that actin functions in numerous previously unrecognized processes. Most spectacularly, the directed vesicle expansions of the cytokinetic system involve newly formed actin which outlines the developing zoospores. Disruption of this actin with cytochalasins leads to abnormal cleavage as witnessed by the formation of enlarged and irregular cysts. Prior to cytokinesis, two new types of organelle are synthesized and one, known as K bodies, clusters around the nuclei. These organdies are actin-rich during development and clustering, consistent with actin functioning in their positioning. In the zoospores, actin is concentrated around the water expulsion vacuoles, indicating that they are contractile, and permeates the cytoplasm, probably with a skeletal role. This concept is supported by the first demonstration of actin specifically associated with a microtubular root in the secondary zoospore. Upon encystment there is a dramatic increase in stained actin in the form of peripheral plaques associated with the newly synthesized cell wall. When the cysts germinate, a fibrillar actin cap, comparable to that previously described in hyphal tips, forms in the germ tube apex, but only after cell wall softening to permit germ tube protrusion. This sequence is consistent with the actin cap modulating turgor-driven expansion of the tip as previously discussed for hyphae. In addition to disrupting cleavage-associated actin, cytochalasins show developmental stage, dose and drug (CE≥CD≥CB) specific effects on zoosporulation-related actin, which indicates that, contrary to previous suggestions, rhodamine-phalloidin staining is a useful indicator of actin behaviour in response to cytochalasins. These responses include differential effects on adjoining actin arrays, some of which are transient in the continued presence of the drugs, indicating a mechanism of drug adaptation.

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