Transpiration efficiency (TE), the biomass produced per unit of water transpired, is a key trait for crop performance under limited water. As water becomes scarce, increasing TE would contribute to increase crop drought tolerance. This study is a first step to explore pearl millet genotypic variability for TE on a large and representative diversity panel. We analyzed TE on 537 pearl millet genotypes, including inbred lines, test-cross hybrids, and hybrids bred for different agroecological zones. Three lysimeter trials were conducted in 2012, 2013 and 2015, to assess TE both under well-watered and terminal-water stress conditions. We recorded grain yield to assess its relationship with TE. Up to two-fold variation for TE was observed over the accessions used. Mean TE varied between inbred and testcross hybrids, across years and was slightly higher under water stress. TE also differed among hybrids developed for three agroecological zones, being higher in hybrids bred for the wetter zone, underlining the importance of selecting germplasm according to the target area. Environmental conditions triggered large Genotype x Environment (GxE) interactions, although TE showed some high heritability. Transpiration efficiency was the second contributor to grain yield after harvest index, highlighting the importance of integrating it into pearl millet breeding programs. Future research on TE in pearl millet should focus (i) on investigating the causes of its plasticity i.e. the GxE interaction (ii) on studying its genetic basis and its association with other important physiological traits.
- MeSH
- biomasa MeSH
- genetická variace MeSH
- genotyp * MeSH
- období sucha MeSH
- Pennisetum * genetika fyziologie růst a vývoj MeSH
- šlechtění rostlin metody MeSH
- transpirace rostlin * fyziologie MeSH
- voda metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- voda MeSH
Δ1-pyrroline-5-carboxylate synthetase (P5CS) is one of the key regulatory enzymes involved in the proline biosynthetic pathway. Proline acts as an osmoprotectant, molecular chaperone, antioxidant, and regulator of redox homeostasis. The accumulation of proline during stress is believed to confer tolerance in plants. In this study, we cloned the complete CDS of the P5CS from pearl millet (Pennisetum glaucum (L.) R.Br. and transformed into tobacco. Three transgenic tobacco plants with single-copy insertion were analyzed for drought and heat stress tolerance. No difference was observed between transgenic and wild-type (WT) plants when both were grown in normal conditions. However, under heat and drought, transgenic plants have been found to have higher chlorophyll, relative water, and proline content, and lower malondialdehyde (MDA) levels than WT plants. The photosynthetic parameters (stomatal conductance, intracellular CO2 concentration, and transpiration rate) were also observed to be high in transgenic plants under abiotic stress conditions. qRT-PCR analysis revealed that the expression of the transgene in drought and heat conditions was 2-10 and 2-7.5 fold higher than in normal conditions, respectively. Surprisingly, only P5CS was increased under heat stress conditions, indicating the possibility of feedback inhibition. Our results demonstrate the positive role of PgP5CS in enhancing abiotic stress tolerance in tobacco, suggesting its possible use to increase abiotic stress-tolerance in crops for sustained yield under adverse climatic conditions.
- Klíčová slova
- Pennisetum glaucum, Functional validation, Gene P5CS, Proline, Transgenic,
- MeSH
- chlorofyl metabolismus MeSH
- fotosyntéza genetika MeSH
- fyziologický stres * genetika MeSH
- geneticky modifikované rostliny * genetika růst a vývoj MeSH
- období sucha * MeSH
- Pennisetum genetika metabolismus MeSH
- prolin * metabolismus MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné proteiny genetika metabolismus MeSH
- tabák * genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorofyl MeSH
- prolin * MeSH
- rostlinné proteiny MeSH
