High Temperature Tolerance in a Novel, High-Quality Phaseolus vulgaris Breeding Line Is Due to Maintenance of Pollen Viability and Successful Germination on the Stigma
Author:
Rose Teresa1ORCID, Lowe Claudia1ORCID, Miret Javier A.2ORCID, Walpole Hannah1ORCID, Halsey Kirstie1ORCID, Venter Eudri1ORCID, Urban Milan O.3ORCID, Buendia Hector Fabio3, Kurup Smita1ORCID, O’Sullivan Donal Martin2ORCID, Beebe Steve3, Heuer Sigrid4ORCID
Affiliation:
1. Rothamsted Research, Harpenden AL5 2JQ, UK 2. Department of Crop Science, University of Reading, Whiteknights P.O. Box 217, Reading, Berkshire RG6 6AH, UK 3. Centro Internacional de Agricultura Tropical (CIAT), Kilometro 17, Recta Cali-Palmira, Apartado Aereo, Cali 6713, Colombia 4. National Institute of Agricultural Botany (NIAB), Lawrence Weaver Road, Cambridge CB3 0LE, UK
Abstract
The common bean (Phaseolus vulgaris L.) is an important nutritional source globally but is sensitive to high temperatures and thus particularly vulnerable to climate change. Derived from a breeding program at CIAT (Colombia), a heat-tolerant breeding line, named heat-tolerant Andean-type 4 (HTA4), was developed by a series of crosses of parents with a small-bean tepary genotype (Phaseolus acutifolius L.) in their pedigree, which might be the donor of heat stress (HS) tolerance. Importantly, in HTA4, the large, commercially desirable Andean-type beans was restored. To assess underlying tolerance mechanisms, HTA4, together with a heat-sensitive Colombian variety (Calima), was exposed to HS (31 °C/24 °C HS vs. 26 °C/19 °C day/night) under controlled environment conditions. Vegetative growth and photosynthetic performance were not negatively impacted by HS in either genotype, although senescence was delayed in Calima. HS during the reproductive stage caused an increase in pod number in Calima but with few fully developed seeds and many pods aborted and/or abscised. In contrast, HTA4 maintained a similar filled pod number under HS and a higher seed weight per plant. Pollen showed high sterility in Calima, with many non-viable pollen grains (24.9% viability compared to 98.4% in control) with a thicker exine and fewer starch granules under HS. Calima pollen failed to adhere to the stigma and germinate under HS. In HTA4, pollen viability was significantly higher than in Calima (71.1% viability compared to 95.4% under control), and pollen successfully germinated and formed pollen tubes in the style under HS. It is concluded that HTA4 is heat tolerant and maintains a high level of reproductive output due to its ability to produce healthy pollen that is able to adhere to the stigma.
Funder
Biotechnology and Biological Sciences Research Council of the United Kingdom Research Council UK—Centro Internacional de Agricultura Tropical (RCUK-CIAT) Newton Fund BBSRC National Institute of Agricultural Botany Gray Foundation
Subject
Plant Science,Ecology,Ecology, Evolution, Behavior and Systematics
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