Transcriptomic analysis reveals key transcription factors associated to drought tolerance in a wild papaya (Carica papaya) genotype

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.

Papaya: The Versatile Tropical Fruit

“…Drought tolerant papaya was shown to have greater photosynthetic II (PSII) efficiency than susceptible ones. Susceptible plants displayed greater leaf abscission, less turgid shoots, and lower plant growth than those of more tolerant ones [30].…”

“…Drought susceptible plants displayed greater leaf abscission, less turgid shoots, and lower plant growth than those of tolerant papaya. Molecular analysis identified six transcription factors including CpHSF, CpMYB, CpNAC, CpNFY-A, CpERF, and CpWRKY that were highly expressed in tolerant papaya [30]. These genes were reportedly also involved in drought tolerance in rice and maize [31,32].…”

Brassinosteroids induced drought resistance of contrasting drought-responsive genotypes of maize at physiological and transcriptomic levels

“…Furthermore, all four sets of BRs showed that the “extracellular region” and “starch metabolic cycle,” showing two lines, included similar drought blockage components ( Zenda et al., 2018 ). PCA revealed the identical characteristics of both plants, including the relevance of numerous limitations ( Estrella-Maldonado et al., 2021 ). Each rate is shown with the eigenvalues in the PCA evaluation, indicating that these characteristics are accurate and connected to the other rates ( Table 3 ).…”

“…The maize plant has a simple structure, and its unique germplasm makes it a more valuable crop than other cereals ( Corso et al., 2015 ). Although significant progress has been made in investigating maize response to drought stress, previous studies have focused on physiological and metabolic or single-trait responses ( Estrella-Maldonado et al., 2021 ). The high-throughput sequencing frameworks that rely on the RNA level and their analysis results have profoundly changed our viewpoint on the extent and heterogeneity of the maize transcriptome to a substantial degree over the last decade ( Faghani et al, 2015 ).…”

Genomic Approaches for Improvement of Tropical Fruits: Fruit Quality, Shelf Life and Nutrient Content

“…On the other hand, 40 potential microRNAs related to salinity stress and their target transcripts were characterized in guava [ 103 ]. Transcription factors regulating drought stress tolerance were examined in papaya and belong to TF families such as CpHSF , CpMYB , CpNAC , CpNFY-A , CpERF and CpWRKY [ 63 , 191 ]. Though there is no genetic information on drought stress related mechanisms in jackfruit, SSR markers developed and QTLs identified for drought tolerant root traits in mulberry can be studied for assessing the jackfruit germplasm, as they showed 79.25% transferability to cross species [ 192 ].…”