Comprehensive analysis of NAC transcription factor family uncovers drought and salinity stress response in pearl millet ( Pennisetum glaucum)

Abstract

Background: Pearl millet (Pennisetum glaucum) is a cereal crop that possesses the ability to withstand drought, salinity and high temperature stresses. The NAC [NAM (No Apical Meristem), ATAF1 (Arabidopsis thaliana Activation Factor 1), and CUC2 (Cup-shaped Cotyledon)] transcription factor family is one of the largest transcription factor families in plants. NAC family members are known to regulate plant growth and abiotic stress response. Currently, no reports are available on the functions of the NAC family in pearl millet. Results: Our genome-wide analysis found 151 NAC transcription factor genes (PgNACs) in the pearl millet genome. Thirty-eight and 76 PgNACs were found to be segmental and dispersed duplicated respectively. Phylogenetic analysis divided these NAC transcription factors into 11 groups (A-K). Three PgNACs (-073, -29, and -151) were found to be membrane-associated transcription factors. Seventeen other conserved motifs were found in PgNACs. Based on the similarity of PgNACs to NAC proteins in other species, the functions of PgNACs were predicted. In total, 88 microRNA target sites were predicted in 59 PgNACs. A previously performed transcriptome analysis suggests that the expression of 30 and 42 PgNACs are affected by salinity stress and drought stress, respectively. The expression of 36 randomly selected PgNACs were examined by quantitative reverse transcription-PCR. Many of these genes showed diverse salt- and drought-responsive expression patterns in roots and leaves. These results confirm that PgNACs are potentially involved in regulating abiotic stress tolerance in pearl millet.Conclusion: The pearl millet genome contains 151 NAC transcription factor genes that can be classified into 11 groups. Many of these genes are either upregulated or downregulated by either salinity or drought stress and may therefore contribute to establishing stress tolerance in pearl millet.

Root plasticity under abiotic stress

“…Another salt stress-responding MYB TF, SUBERMAN (MYB39) enhances suberin deposition in the endodermis ( Cohen et al, 2020 ). Other salt/drought stress induced TFs such as NACs ( Jeong et al, 2013 ; Dudhate et al, 2021 ) and WRKYs ( Krishnamurthy et al, 2020 ) have also been shown to stimulate the suberin biosynthesis pathway. ABA appears to promote suberization whereas ethylene represses this process ( Barberon et al, 2016 ).…”

Deciphering trait associated morpho-physiological responses in pearlmillet hybrids and inbred lines under salt stress

“…This could possibly be due to partial stomatal closure leading to reduction in intercellular CO 2 concentration or chlorophyll degradation or reduced enzymatic activities or down regulation of proteins required to maintain structural integrity of photosystems (Kumar et al, 2016). Dudhate et al (2018) also reported reduced photosynthesis due to decreased CC and SPAD values in pearl millet when exposed to drought stress. The genotypic differences and disturbed enzymes activities of ROS and photosynthetic pigments has also been reported earlier depicting their correlation with the presence or absence of a major terminal drought tolerance QTL (Kholova et al, 2011).…”

Genome‐wide miRNAs profiles of pearl millet under contrasting high vapor pressure deficit reveal their functional roles in drought stress adaptations

“…Numerous genes having implications on drought tolerance have been identified (Dudhate et al, 2021; Shinozaki & Yamaguchi‐Shinozaki, 2007). These genes mainly code for proteins involved in osmolyte biosynthesis (Umezawa et al, 2006), protective proteins (such as LEA, heat shock proteins, and dehydrins; Reddy et al, 2012; Reddy et al, 2016; Singh et al, 2015), ROS scavenging proteins (Chakradhar et al, 2017; Reddy et al, 2009), ABA homeostasis (Seiler et al, 2011), and water and ion transport proteins (Jarzyniak & Jasinski, 2014).…”