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| Author(s): |
Maria Dolores Pissolato
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2024-01-19 |
| Examining board members: |
Rafael Vasconcelos Ribeiro;
Sara Adrián López de Andrade;
Eduardo Caruso Machado;
Gustavo Maia Souza;
Neidiquele Maria Silveira
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| Advisor: | Rafael Vasconcelos Ribeiro |
| Abstract | |
The drought represents the most significant environmental stress limiting the growth of sugarcane and is expected to worsen due to climate changes. Many responses to environmental stresses involve molecular, metabolic, physiological, and structural changes in different plant organs. If these changes not only enable the plant to survive at the specific moment of exposure to the stressful event but also in future events, it constitutes a case of stress memory. Stress memory enhances plant tolerance to subsequent stresses and can persist in the current generation (somatic memory) as well as in its offspring (inter and transgenerational memory). Our objectives were: (a) to assess the development of drought memory at different phenological stages of two sugarcane genotypes, IACCTC07-8008 (drought-tolerant) and IACSP95-5000 (high productivity), through the analysis of primary metabolism and physiological responses. For this, plants of both genotypes were exposed to three cycles of water deficit (D1, 2, and 3) and rehydration during the tillering (T) or maturation (M) phase, with one group kept irrigated throughout the experimental period (W); (b) to assess the intergenerational memory of propagules obtained from stressed plants in T and M through physiological analyses and metabolomic profiling, and finally (c) to evaluate the final productivity and juice quality of stalks from propagules grown in the field and obtained from plants stressed in T or M. The results demonstrated that in D2 and D3, both genotypes stressed in T or M showed foliar accumulation of various metabolites compared to D1, such as amino acids (proline, glycine, valine, methionine, leucine, isoleucine, phenylalanine, asparagine. serine, ornithine), sugars (sucrose, fructose, glucose), polyols (glycerol, myo-inositol), and organic acids (succinate, fumarate, malate, threonate, glycerate). The identified metabolites were related to the better physiological performance of these plants in D2 and D3. Despite the reduction in CO2 assimilation in response to reduced soil water availability during the three water deficit cycles, plants exposed to D2 and D3 showed a less pronounced reduction in photosynthesis than when exposed to D1. We also observed greater intrinsic water use efficiency (WUEi) in D2 and D3 for the drought-tolerant genotype compared to D1 in T and M. The productive genotype showed significantly higher WUEi in D3 compared to D1 in T and M. Propagules from both genotypes obtained from T and M, when subjected to water deficit, exhibited faster photosynthetic recovery than propagules obtained from W plants, as well as being more water-use efficient. This better performance in physiological parameters resulted in greater shoot (SDM) and root (RDM) dry mass. We also observed the accumulation of primary foliar metabolites (similar to those found in the origin material) in propagules from both genotypes obtained from stressed plants in T and M, compared to propagules obtained from W. In the field, propagules from the drought-tolerant genotype obtained from M showed higher stalk yield, SDM, leaf area index (LAI), and sucrose content (POL%) compared to propagules obtained from T or W. For the productive genotype, we observed an increase in stalk yield, SDM, and LAI when obtained from T. A higher root volume was also found for propagules from both genotypes obtained from T and M. The vegetative propagation of sugarcane involves stalk segments containing a lateral bud, thus, it can be inferred that the inherited memory of plants is stored in the meristematic tissues of the buds. Our results confirm that drought memory is developed in sugarcane in both genotypes regardless of the phenological stage and that primary metabolites associated with energy balance and osmoregulation to maintain cell turgor and deal with free radicals are related to drought memory in these plants. Furthermore, the choice of origin material to be propagated has a significant impact on crop yield in the field (AU) | |
| FAPESP's process: | 19/27106-0 - Alterations in transcriptome, metabolome and physiological responses associated with sugarcane drought memory |
| Grantee: | Maria Dolores Pissolato |
| Support Opportunities: | Scholarships in Brazil - Doctorate |