Physiological factors limit fruit set of tomato (Lycopersicon esculentum Mill.) under chronic, mild heat stress

Abstract

The effects of chronic, mild heat stress on fruit set, fruit production, release of pollen grains, photosynthesis, night respiration and anther dehiscence were examined in tomatoes (Lycopersicon esculentum Mill.) differing in high-temperature sensitivity. Plants were grown under three temperature regimes: (1) 28/22 or 26/22 °C (optimal temperature); (2) 32/26 °C (high temperature); and (3) 32/26 °C day/night temperatures relieved at 28/22 °C for 10 d before anthesis, then returned to 32/26 °C (relieving treatment). FLA 7156 was the only cultivar with fruit set at 32/26 °C. All five cultivars, however, had fruit set under the relieving treatment (RT). The longer the relief, the higher the percentage of fruit set. Longer periods of relief also increased the number of pollen grains released, and linear regression analysis showed a significant relationship between the number of pollen grains released and the percentage of fruit set. Germination of pollen grains was also lowered in high-temperature-grown plants. The number of pollen grains produced, photosynthesis and night respiration did not limit fruit set under chronic, mild heat stress, however. This suggested that cultivar differences in pollen release and germination under heat stress are the most important factors determining their ability to set fruit.

Exploring the natural variation for reproductive thermotolerance in wild tomato species

“…Given the previously reported correlation between PV and fruit set under LTMH (e.g. Dane et al 1991;Sato et al 2000;Xu et al 2017b), we conclude that wild germplasm might indeed be a valuable resource to enrich domesticated germplasm for reproductive thermotolerance.…”

“…The reduction in tomato yield under long-term mild heat (LTMH) may be attributed to the plant's vulnerability during reproductive development, resulting in a lower number of pollen per flower (PN) and pollen viability (PV) (Dane et al 1991;Firon et al 2006;Kinet and Peet 1997;Levy et al 1978;Peet et al 1998;Pressman 2002;Pressman et al 2006;Sato et al 2000Sato et al , 2006Xu et al 2017b). In this study, we analysed the natural variation of reproductive thermotolerance in wild tomato species, which may serve as gene sources for cultivated tomato.…”

“…As an alternative approach, it might be more effective to analyse the various contributing sub-traits individually and combine them afterwards in a breeding context. For example, decreases in tomato fruit set under long-term mildly elevated temperatures has been shown to correlate with a decrease in pollen viability (Dane et al 1991;Firon et al 2006;Kinet and Peet 1997;Levy et al 1978;Peet et al 1998;Pressman 2002;Pressman et al 2006;Sato et al 2000Sato et al , 2006Xu et al 2017b). Also, style protrusion may affect reproductive success under high temperature (Charles and Harris 1972;Dane et al 1991;Rick and Dempsey 1969;Rudich et al 1977;Saeed et al 2007;Xu et al 2017b).…”

HsfA2 Controls the Activity of Developmentally and Stress-Regulated Heat Stress Protection Mechanisms in Tomato Male Reproductive Tissues

“…Anther dehiscence that leads to pollen release is a complex process requiring successive cell differentiation and degeneration of specific tissues (Sato et al, 2000). The cell wall was the highest represented functional category among the 76 HsfA2-regulated genes, including genes encoding for enzymes related to cell wall remodeling, such as pectin methylesterases, pectin acetylesterases, and pectate lyases (Supplemental Table S6).…”

Sensitivity of flowering plant gametophytes to temperature fluctuations

“…In a different series of experiments carried out in common bean (Phaseolus vulgaris L.) (Prasad et al, 2002) and groundnut (Arachis hypogaea L.) (Prasad et al, 2003), and characterizing the Page 7 of 24 A c c e p t e d M a n u s c r i p t 7 combined effect of high temperatures and CO2, the beneficial effect of CO2 increase on vegetative growth and photosynthesis was not sufficient to offset the negative effects of high temperature on reproductive processes and yield. In tomato, although moderately elevated temperature stress (METS; 32/26ºC) did not cause significant changes in biomass, photosynthesis, and night respiration, fruit set was significantly reduced (Sato et al, 2000). In some studies of floral abortion under temperature stress, the observed reduction in carbohydrate supply to the reproductive tissues was attributed rather to reduction in sink demand (e.g.…”