Temperature related instability of a naturally induced cytoplasmic male sterility in industrial chicory (Cichorium intybus L.)

Abstract

Natural alloplasmic cytoplasmic male sterile (CMS) clones of industrial chicory were obtained after crossing wild chicory with selected breeding lines. We investigated the CMS stability of 10 clones in various environmental growing conditions. CMS was stable under cool growing conditions in most of them. Fertility restoration, based on pollen production scores, was observed in all clones after a period of hot temperatures. The early flower bud stage was sensitive, resulting in fertile flowers 12-17 days after exposure to high temperatures. Experiments under controlled growing conditions at 15°C demonstrated that a heat shock of 2 days at 25 or 30°C was sufficient to restore fertility. Sterile flowers were formed when plants were again grown at lower temperatures. Significant differences between individual clones were observed, indicating the potential of genetic selection to obtain stable CMS parent lines. K E Y W O R D Salloplasmic male sterility, cytoplasmic male sterility, fertility, heat shock, pollen production

Industrial chicory genome gives insights into the molecular timetable of anther development and male sterility

“…For transcriptome and morphological analysis of flower buds, an industrial chicory clone (K1337) and an inbred line (L8018) were used as fertile control lines with normal pollen production (referred to as ‘fertile’), in addition to CMS clones 12-712-30 (CMS30) and 12-712-36 (CMS36). Both CMS clones can become fertile under favorable environmental circumstances, such as elevated temperatures during anther development, but CMS30 shows more stable male sterility, while CMS36 shows full fertility restoration (Van der Veken, Vandermoere et al 2018). All plants were kept on the field protected by a plastic cover during winter for vernalization and grown on a container field until bolting.…”

“…The response time between heat shock and fertility restoration was three weeks, suggesting that early stage flower buds (size between 2 mm and 4 mm) are most responsive to fertility restoration. CMS30 male sterility was more robust as only few pollen were produced after a heat shock, whereas in CMS36 full fertility restoration was observed (Van der Veken, Vandermoere et al 2018).…”

“…Here, we studied two chicory CMS clones; CMS36 and CMS30. These CMS clones were developed by crossing a wild chicory genotype with an inbred line of industrial chicory (Van der Veken, Vandermoere et al 2018). In subsequent backcrosses with industrial chicory progressively fewer pollen was produced until no pollen was present in the third and fourth backcross generation.…”

“…While the cause and mechanism of male sterility is unknown in these clones, CMS may result from the incompatibility between wild chicory cytoplasm and industrial chicory nuclei. However, in both CMS clones fertility could be restored at elevated temperature (Van der Veken, Vandermoere et al 2018). The response time between heat shock and fertility restoration was three weeks, suggesting that early stage flower buds (size between 2 mm and 4 mm) are most responsive to fertility restoration.…”

Industrial chicory genome gives insights into the molecular timetable of anther development and male sterility

“…Late stage upregulation of CiVI coincides with vacuolization in chicory pollen (Figures 5F, G, 6). Such CiVI have been found to be highly upregulated during etiolated leaf growth in chicory and this is indicative of a growing sink tissue (Van den Ende et al, 2002). In addition, as VI produces large amounts of fructose and glucose, an osmotic effect is generated that could be the driving force behind pollen vacuolization (Van den Ende et al, 2002).…”