Resilience of rice (Oryza spp.) pollen germination and tube growth to temperature stress

Abstract

Resilience of rice cropping systems to potential global climate change will partly depend on the temperature tolerance of pollen germination (PG) and tube growth (PTG). Pollen germination of high temperature-susceptible Oryza glaberrima Steud. (cv. CG14) and Oryza sativa L. ssp. indica (cv. IR64) and high temperature-tolerant O. sativa ssp. aus (cv. N22), was assessed on a 5.6-45.4 °C temperature gradient system. Mean maximum PG was 85% at 27 °C with 1488 μm PTG at 25 °C. The hypothesis that in each pollen grain, the minimum temperature requirements (Tn ) and maximum temperature limits (Tx ) for germination operate independently was accepted by comparing multiplicative and subtractive probability models. The maximum temperature limit for PG in 50% of grains (Tx(50) ) was the lowest (29.8 °C) in IR64 compared with CG14 (34.3 °C) and N22 (35.6 °C). Standard deviation (sx ) of Tx was also low in IR64 (2.3 °C) suggesting that the mechanism of IR64's susceptibility to high temperatures may relate to PG. Optimum germination temperatures and thermal times for 1 mm PTG were not linked to tolerating high temperatures at anthesis. However, the parameters Tx(50) and sx in the germination model define new pragmatic criteria for successful and resilient PG, preferable to the more traditional cardinal (maximum and minimum) temperatures.

Resilience of Pollen and Post‐Flowering Response in Diverse Sorghum Genotypes Exposed to Heat Stress under Field Conditions

“…A similar differential response of pollen to calcium concentration was observed in three contrasting rice genotypes tested for viability and temperature stress resilience under a wide range of temperatures (Coast et al, 2016). A similar differential response of pollen to calcium concentration was observed in three contrasting rice genotypes tested for viability and temperature stress resilience under a wide range of temperatures (Coast et al, 2016).…”

“…In vitro pollen germination revealed SC155 to possess true heat-tolerant pollen, even under severe stress exposure. A significant positive relationship between seed set percentage and in vitro pollen germination has been documented in cereals including rice and sorghum ( Jagadish et al, 2010;Nguyen et al, 2013;Djanaguiraman et al, 2014;Singh et al, 2015;Coast et al, 2016). Sorghum, a dryland semiarid crop, is often grown in environments with mean day temperatures of 33 to 35°C (slightly higher than the optimum temperature for sorghum growth; Maiti, 1996), with the predicted increase in global temperatures pushing its cultivation to harsher conditions.…”

Quantifying the Impact of Heat Stress on Pollen Germination, Seed Set, and Grain Filling in Spring Wheat

“…Upon exposure to heat stress (34°C, daytime temperature), Fig. A similar negative impact of heat stress on pollen germination was documented in rice (Coast et al, 2016), sorghum , and peanut (Kakani et al, 2002). Phenotypic variability of spring wheat genotypes exposed to heat stress (34/16°C) during flowering (HS Flowering for 10 d in Exp.…”

“…Wheat has different optimum temperatures for both vegetative and reproductive stages, which vary between species and genotypes (Farooq et al, 2011). Pollen viability is a major determinant of reproductive success, and its genetic variability under heat stress exposure has been documented in rice (Oryza sativa L.; Coast et al, 2016), sorghum [Sorghum bicolor (L.) Moench; Sunoj et al, 2017], peanut (Arachis hypogaea L.; Kakani et al, 2002), and soybean [Glycine max (L.) Merr. Pollen viability is a major determinant of reproductive success, and its genetic variability under heat stress exposure has been documented in rice (Oryza sativa L.; Coast et al, 2016), sorghum [Sorghum bicolor (L.) Moench; Sunoj et al, 2017], peanut (Arachis hypogaea L.; Kakani et al, 2002), and soybean [Glycine max (L.) Merr.…”

Temporal Petal Closure Benefits Reproductive Development of Magnolia denudata (Magnoliaceae) in Early Spring

“…In this study, pollen dehiscence was delayed, pollen germination was low, and pollen tube growth was slow, when the floral chamber was disturbed in M. denudata . It has been demonstrated in plants with both thermogenic and non-thermogenic flowers that pollen function was considerably affected by temperature (Seymour et al, 2009b; Coast et al, 2016), which might involve regulation mediated by the GA pathway and Ca 2+ signals (Mähs et al, 2013; Sakata et al, 2014). Thus, retardance of heat loss by the floral chamber may also play a role in facilitating pollen function.…”