Abstract
Most of the commercial papaya genotypes show susceptibility to water deficit stress and require high volumes of irrigation water to yield properly. To tackle this problem, we have collected wild native genotypes of Carica papaya that have proved to show better physiological performance under water deficit stress than the commercial cultivar grown in Mexico. In the present study, plants from a wild Carica papaya genotype and a commercial genotype were subjected to water deficit stress (WDS), and their response was characterized in physiological and molecular terms. The physiological parameters measured (water potential, photosynthesis, Fv/Fm and electrolyte leakage) confirmed that the papaya wild genotype showed better physiological responses than the commercial one when exposed to WDS. Subsequently, RNA-Seq was performed for 4 cDNA libraries in both genotypes (susceptible and tolerant) under well-watered conditions, and when they were subjected to WDS for 14 days. Consistently, differential expression analysis revealed that after 14 days of WDS, the wild tolerant genotype had a higher number of up-regulated genes, and a higher number of transcription factors (TF) that were differentially expressed in response to WDS, than the commercial genotype. Thus, six TF genes (CpHSF, CpMYB, CpNAC, CpNFY-A, CpERF and CpWRKY) were selected for further qRT-PCR analysis as they were highly expressed in response to WDS in the wild papaya genotype. qRT-PCR results confirmed that the wild genotype had higher expression levels (REL) in all 6 TF genes than the commercial genotype. Our transcriptomic analysis should help to unravel candidate genes that may be useful in the development of new drought-tolerant cultivars of this important tropical crop.
Highlights
Drought stress is worldwide considered as the single most common limitation for agricultural production and represents a great threat that may lead to malnutrition and famine [1]
Comparing the estimated expression levels by RNA-Seq and RT-qPCR, our results indicate that tolerant genotype have higher Relative Expression Levels (REL) than the susceptible genotype for CpHSF, CpMYB, CpNAC, CpNFY-A, CpERF and CpWRKY genes after 14 d.p.t. of water deficit stress (WDS) (Fig 8A–8F). [72] reported that DREB, ERF, MYB, NAC and WRKY transcription factors (TF) genes play an important role in engineering drought tolerance in transgenic plants
The superior drought tolerance of the wild genotype may have resulted from its ability to maintain lower Electrolyte leakage (EL), higher Fv/FM values and higher stomatal conductance than its commercial counterpart when subjected to WDS
Summary
The aim of the present study was to elucidate some of the physiological and molecular mechanisms that allow wild papayas to better tolerate WDS than their commercial counterparts
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
