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King Abdullah University of Science and Technology (KAUST) 2022

Effect of heat stress on in vitro pollen germination and pollen tube elongation of Chenopodium quinoa and wild relatives

Morris, Angel

Titre : Effect of heat stress on in vitro pollen germination and pollen tube elongation of Chenopodium quinoa and wild relatives

Auteur : Morris, Angel

Université de soutenance : King Abdullah University of Science and Technology (KAUST)

Grade : Master of Science (MS) 2022

Résumé
Climate change is one of the biggest challenges facing agriculture today. Transient or prolonged heat stress can be detrimental to plant reproductive development. The male gametophyte, pollen, is particularly sensitive to heat stress, resulting in sterile pollen (pre-anthesis) or deformed/stunted pollen tubes (post-anthesis).

Quinoa (Chenopodium quinoa Willd.) has recently seen a rise in global interest due to its nutritional qualities, but global expansion of quinoa is partially hindered by its susceptibility to heat. It has been hypothesized that introgression of heat tolerance traits from wild relatives that occupy warmer environments can increase thermotolerance in quinoa. The goal of this research was to investigate the effect of heat stress on mature pollen grains from quinoa and its wild relatives, C. berlandieri and C. hircinum.

To answer this question, several experiments were performed : 1. The nuclear number of the pollen of wild relatives was assessed to determine whether mature pollen grains were released at the trinucleate stage. All pollen was found to be trinucleate. 2. Pollen germination medium was optimized for four accessions : C. quinoa (QQ74 ; PI 614886), C. berlandieri var. zschackei (CB ; BYU14118), and C. hircinum (CHA ; Hircinum-069 and CHC ; BYU17105). Optimal sucrose and PEG concentrations were determined to be : 5% sucrose/20% PEG for QQ74 and CB ; 20% sucrose/0% PEG for CHA ; and 10% sucrose/20% PEG for CHC. 3. Temperature optima for pollen germination for QQ74 was 32°C-36°C ; CB was 30°C-34°C ; CHA was 36°C ; and CHC was 32°C -34°C. Overall, pollen from wild relatives was not found to be more heat-tolerant than pollen from domesticated quinoa. 4. Pollen tube elongation over time was observed for all four accessions at 34°C and 38°C, with CHA and QQ74 having the lowest decrease in rate at 38°C (35 and 45%, respectively).

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Page publiée le 14 décembre 2022