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To study the effects of high temperature on the meiosis of pollen mother cells (PMCs) and to determine their relationship with grain set, two in situ experiments were conducted between 2010 and 2012 on four wheat cultivars, Kauz, Montana, M6 and Chamran, under normal (normal cultivation) and terminal heat stress (late cultivation) conditions. Due t...
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... (Table 4). The average of genotypes for meiotic abnormalities is presented in Table 5. The results showed that the varieties were significantly different from each other regarding the percentage of these anomalies; the M6 and Montana varieties had the most quantity of abnormalities with respective means of 21.1 and 12%, and had a significant difference (p ≤ 0.05) with other varieties. ...Similar publications
Cytogenetical studies have been undertaken to assess the consequences of induced colchiploids and its reflection on meiotic index (MI) and pollen viability (PV) in Brassica campestris L. during microsporogenesis. Colchiploids of Brassica obtained at 0.3%-0.5% doses were administered as meiotically stable since they possessed MI and PV between 90%-1...
Citations
... Fruit and seeds, major edible organs of many crops, are mainly derived from sexual reproduction. However, the reproductive process as well as the development of floral organs, particularly pollen (Muller and Rieu, 2016; Frontiers in Plant Science 02 frontiersin.org Smith, 2019), are very sensitive to high temperature (Hoshikawa et al., 2021). ...
... For long-term heat stress, high temperature induces premature degeneration of the tapetal cell layer, inhibits pollen development by restricting the supply of nutrients, enzymes, and precursors from tapetum (Baron et al., 2012;Omidi et al., 2014;Qi et al., 2018). It is known that reactive oxygen species (ROS) are important factors regulating tapetal degeneration in Arabidopsis, rice and tomato (Hu et al., 2011;Luo et al., 2013;Xie et al., 2014;Yu et al., 2017). ...
... High temperature greatly affects pollen development and pollen growth in plants, leading to tremendous loss in fruit quality and yield of many crops (Muller and Rieu, 2016;Smith, 2019;Hoshikawa et al., 2021). In this study, we showed that short-term heat stress-induced pollen growth defects and long-term heat stress-induced pollen developmental defects were both alleviated by ZNC pretreatment. ...
High temperature negatively affects reproductive process significantly, leading to tremendous losses in crop quality and yield. Zhinengcong (ZNC), a crude extract from the endophytic fungus Paecilomyces variotii , has been shown to improve plant growth and resistance to biotic and abiotic stresses. We show here that ZNC can also alleviate heat stress-induced reproductive defects in Solanum lycopersicum , such as short-term heat-induced inhibition on pollen viability, germination and tube growth, and long-term heat stress-induced pollen developmental defects. We further demonstrated that ZNC alleviates heat stress by downregulating the expressions of ROS production-related genes, RBOHs, and upregulating antioxidant related genes and the activities of the corresponding enzymes, thus preventing the over accumulation of heat-induced reactive oxygen species (ROS) in anther, pollen grain and pollen tube. Furthermore, spraying application of ZNC onto tomato plants under long-term heat stress promotes fruit and seed bearing in the field. In summary, plant endophytic fungus extract ZNC promotes the reproductive process and yield of tomato plants under heat stress and presents excellent potential in agricultural applications.
... AIL between 3 and 6 cm has been associated with this sensitive stage (Bokshi et al., 2021;Erena et al., 2021). Brief heat exposure during this sensitive period resulted in abnormal meiosis behavior (Omidi et al., 2014;Draeger and Moore, 2017) and a significant reduction in pollen fertility (Prasad and Djanaguiraman, 2014;Begcy et al., 2018;Browne et al., 2021). A few studies have examined the natural variation in pollen viability under heat stress and its association with yield, as booting usually occurs during the cooler time of the cropping season and it is difficult to apply precise stagespecific heat stress (Bheemanahalli et al., 2019;Bokshi et al., 2021). ...
Rising temperatures due to climate change threaten agricultural crop productivity. As
a cool-season crop, wheat is heat-sensitive, but often exposed to high temperatures
during the cultivation period. In the current study, a bread wheat panel of spring
wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes,
was exposed to a 5-day mild (34�C/28�C, day/night) or extreme (37�C/27�C) heat
stress during the sensitive pollen developmental stage. Worsening effects on anther
morphology were observed, as heat stress increased from mild to extreme. Even under
mild heat, a significant decrease in pollen viability and number of grains per spike
from primary spike was observed compared with the control (21�C/15�C), with Sunstar
and two CIMMYT breeding lines performing well. A heat-specific positive correlation
between the two traits indicates the important role of pollen fertility for grain setting.
Interestingly, both mild and extreme heat induced development of new tillers after
the heat stress, providing an alternative sink for accumulated photosynthates and
significantly contributing to the final yield. Measurements of flag leaf maximum potential
quantum efficiency of photosystem II (Fv/Fm) showed an initial inhibition after the heat
treatment, followed by a full recovery within a few days. Despite this, model fitting using
chlorophyll soil plant analysis development (SPAD) measurements showed an earlier
onset or faster senescence rate under heat stress. The data presented here provide
interesting entry points for further research into pollen fertility, tillering dynamics, and leaf
senescence under heat. The identified heat-tolerant wheat genotypes can be used to
dissect the underlying mechanisms and breed climate-resilient wheat.
... AIL between 3 and 6 cm has been associated with this sensitive stage (Bokshi et al., 2021;Erena et al., 2021). Brief heat exposure during this sensitive period resulted in abnormal meiosis behavior (Omidi et al., 2014;Draeger and Moore, 2017) and a significant reduction in pollen fertility (Prasad and Djanaguiraman, 2014;Begcy et al., 2018;Browne et al., 2021). A few studies have examined the natural variation in pollen viability under heat stress and its association with yield, as booting usually occurs during the cooler time of the cropping season and it is difficult to apply precise stagespecific heat stress (Bheemanahalli et al., 2019;Bokshi et al., 2021). ...
Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop, wheat is heat-sensitive, but often exposed to high temperatures during the cultivation period. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34°C/28°C, day/night) or extreme (37°C/27°C) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed, as heat stress increased from mild to extreme. Even under mild heat, a significant decrease in pollen viability and number of grains per spike from primary spike was observed compared with the control (21°C/15°C), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll soil plant analysis development (SPAD) measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics, and leaf senescence under heat. The identified heat-tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat.
... This was the most important reason for the great number of dyads (as a result of the fused or parallel spindle) and triad (result of the tripolar spindle) found in that genotype. Similar disturbances during the second meiotic division, a consequence of abiotic stress have been described in the work of a number of authors in different crops [14][15][16][17] ]. ...
The meiotic behaviour of pollen mother cells has a key role in the male gametophyte development and realizing the production in the vegetable crops. Due to that reason, the investigation of the microsporogenesis response towards the abiotic stress takes more and more central role in nowadays breeding. The current study includes cytological analysis of the PMCs meiosis that could serve for evaluation of the drought tolerance achieved through decreasing the watering standard by 50% in eight pepper Capsicum annuum L. genotypes. It was found that the water deficit influences negatively over the nuclear restitution in the studied genotypes as in 62.8% of all studied PMCs were found disturbances from type: non-oriented chromosome with irregularities in the division spindles and lagged chromosomes. The disturbances in the chromosome segregation as a result of drought lead to formation of heterogeneous populations of microspores including 17.8% average dyads and triads, 38.9% polyads and 43.2% tetrads. The results obtained will help for not only better understanding of the meiotic division mechanisms and disturbances that occur as a result of the abiotic stress but also contribute for development of economically appropriate germplasm that could respond to the nowadays climate challenges.
... Heat stress post-anthesis reduced grain yield due to a reduction in average individual grain weight [33][34][35][36], but heat stress ≥30 • C at meiosis (or before anthesis) reduced grain yield due to a reduction in grain number [12,24,28,[37][38][39]. Heat stress at meiosis results in unbalanced gametes or unviable gametes due to irregular chromosome segregation (laggards), failure of spindle fiber formation and decreased chiasmata formation [32,[40][41][42]. Deformed or shriveled anthers and ovules, and abnormal pollen, stigma and style development are often observed; thus, heat stress at meiosis affects both male and female fertility [24,43]. ...
... Meiosis in wheat begins around two weeks before anthesis, and most studies evaluate heat stress tolerance during anthesis or seed filling stages [19,22,50]. In this study, we focus on moderate heat stress at meiosis which follows the precedent set in previous studies at meiosis [23,42] and also matches predictions of heat stress during meiosis in the Sirius wheat model [28,29]. We assess the impact of moderate heat stress at meiosis in a diverse range of wheat cultivars previously reported to be heat-tolerant or sensitive. ...
... Omidi et al. [42] reported that heat stress affected meiosis in pollen mother cells, resulting in meiotic abnormalities and decreased PV, which they claimed reduced GN. However, in our study with moderate heat stress at meiosis, PV did not decline much under heat stress and PV was not associated with GN reduction (Figure 4). ...
Meiosis is the least explored stage for thermotolerance in wheat. We evaluated the impact of 5 d of moderate transient daily heat stress during meiosis in the main stem spike on physiological and grain yield traits in 30 diverse wheat cultivars which vary widely in heat tolerance and sensitivity. We found that a moderate heat stress event during meiosis in the main stem spike had lasting impacts on plant growth and reproduction in heat sensitive, but not heat tolerant, wheat cultivars. Heat-tolerant cultivars maintained grain yield, grain number and individual grain weight in the main stem spike and also total plant grain yield and biomass in the heat stress treatment relative to the control. Heat-sensitive cultivars responded to heat stress by producing fewer and smaller grains per spikelet on the main stem, fewer tillers, lower biomass and lower total plant grain yield in the high temperature treatment relative to the control. Heat-sensitive cultivars produced higher flag leaf chlorophyll content in the high temperature treatment relative to the control than heat-tolerant cultivars during the first 3 d of heat treatment. There was small reduction in pollen viability from 98% to 96% following heat stress during meiosis which was unrelated to heat tolerance or sensitivity. Moderate transient heat stress during meiosis did not greatly reduce the production of viable male gametes, but had long-lasting negative impacts on fertilization and subsequent seed production in heat-sensitive cultivars.
... AIL between 3 and 6 cm has been associated with this sensitive stage (Bokshi et al., 2021;Erena et al., 2021). Brief heat exposure during this sensitive period resulted in abnormal meiosis behavior (Omidi et al., 2014;Draeger and Moore, 2017) and a significant reduction in pollen fertility (Prasad and Djanaguiraman, 2014;Begcy et al., 2018;Browne et al., 2021). A few studies have examined the natural variation in pollen viability under heat stress and its association with yield, as booting usually occurs during the cooler time of the cropping season and it is difficult to apply precise stagespecific heat stress (Bheemanahalli et al., 2019;Bokshi et al., 2021). ...
Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop wheat is heat sensitive, but often exposed to high temperatures during cultivation. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34oC/28oC, day/night) or extreme (37oC/27oC) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed as heat stress increased from mild to extreme. Even under mild heat a significant decrease in pollen viability and grain number per spike from primary spike was observed compared with the control (21oC/15oC), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of Photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll SPAD measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics and leaf senescence under heat. The identified tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat.
... Moderately high temperature (30/25°C) causes aberrant mitochondria, ER, and nuclear membranes in PMCs (Oshino et al., 2007). Moreover, abnormal meiosis occurred in PMCs in heat-stressed wheat (Omidi et al., 2014). Recently, abnormal cross-over was observed in Arabidopsis male meiocytes under high temperature (De Storme and Geelen, 2020). ...
In flowering plants, male reproductive development is highly susceptible to heat stress. In this mini-review, we summarized different anomalies in tapetum, microspores, and pollen grains during anther development under heat stress. We then discussed how epigenetic control, particularly DNA methylation, is employed to cope with heat stress in male reproduction. Further understanding of epigenetic mechanisms by which plants manage heat stress during male reproduction will provide new genetic engineering and molecular breeding tools for generating heat-resistant crops.
... Heat stress causes reduction in microspore and pollen cell development (a), reduces pollen dispersal due to abnormal pollen mother cell (b), results in poor pollen production due to nonviable and reduced pollen tube growth (c) and reduces stigma receptivity owing to the disorganized ovary (d) incomplete cellular organization (Saini et al., 1983). Terminal heat stress in wheat causes meiosis abnormalities (micronuclei, absence of metaphase plate, abnormal tetrad, laggard chromosomes, abnormal cytokines, pyknosis and cytomixis) in pollen mother cells (Omidi et al., 2014). In summary, heat stress at the gametophyte stage causes abnormalities in male and female reproductive organs in wheat. ...
Climate change is adversely affecting wheat yields as the associated rising temperatures damage its reproductive physiology. Heat stress affects wheat at various stages of growth, but flowering and reproductive phases are the most sensitive to high temperatures as flower opening usually occurs in cooler environments. Heat stress at meiosis causes ovule and pollen sterility along with anther dehiscence. During pollen development, temperatures >30°C cause pollen abortion. At anthesis, heat stress limit resource translocation to developing grain, resulting in small grain and low yields. During grain development, heat stress shortens the grain-filling duration and decreases starch and protein accumulation due to reduced activity of grain biosynthesis enzymes and impaired flag leaf assimilatory efficiency and stem reserve mobilization. The development of heat-tolerant wheat genotypes through screening, selection, and breeding using genetic engineering, exogenous application of osmoprotectants, and agronomic approaches is a high priority. This review discusses the impact of heat stress on flower development and fertilization, grain development, and reproductive failure in wheat and outlines strategies (i.e., breeding and selection, genetic engineering, molecular breeding, and management) to improve heat tolerance in wheat.
... In addition to genetic causes, environmental factors can lead to fragmentation of genetic material and a high micronucleus index (Diegues et al., 2015). Variation in humidity and increase in temperature can lead to a greater number of meiotic alterations changes (Omidi et al., 2014;Spósito et al., 2015). ...
... Our current Dyad and triad formation at the tetrad stage is a typical outcome of altered chromosome segregation patterns, cell cycle arrest resulting in meiotic restitution, or defects in cytokinesis, which is commonly observed in the anthers of plants grown under adverse temperatures in both dicots (e.g. rose (Pécrix et al. 2011), poplar , and Arabidopsis (De Storme and Geelen 2020)) and monocots (e.g. wheat (Omidi et al. 2014), and barley (Pao and Li 1945)). The ratio and number of dyad and triad formation upon high temperature exposure vary among monocot and dicot species: while Arabidopsis produces primarily triads, rose and poplar produce mainly dyads (De Storme and Geelen 2020; Pécrix et al. 2011;Wang et al. 2017). ...
Key message
Short-term heat stress during male meiosis causes defects in crossover formation, meiotic progression and cell wall formation in the monocot barley, ultimately leading to pollen abortion.
Abstract
High temperature conditions cause a reduction of fertility due to alterations in meiotic processes and gametogenesis. The male gametophyte development has been shown to be particularly sensitive to heat stress, and even short-term and modest temperature shifts cause alterations in crossover formation. In line with previous reports, we observed that male meiosis in the monocot barley exposed for 24–45 h to heat stress (32–42 °C) partially or completely eliminates obligate crossover formation and causes unbalanced chromosome segregation and meiotic abortion. Depending on the severity of heat stress, the structure and organization of the chromosomes were altered. In addition to alterations in chromosome structure and dynamics, heat treatment abolished or reduced the formation of a callose wall surrounding the meiocytes and interrupted the cell cycle progression leading to cytokinesis defects and microspore cell death.
