Simultaneous expression of regulatory genes associated with specific drought‐adaptive traits improves drought adaptation in peanut

Abstract

Adaptation of crops to drought-prone rain-fed conditions can be achieved by improving plant traits such as efficient water mining (by superior root characters) and cellular-level tolerance mechanisms. Pyramiding these drought-adaptive traits by simultaneous expression of genes regulating drought-adaptive mechanisms has phenomenal relevance in improving stress tolerance. In this study, we provide evidence that peanut transgenic plants expressing Alfalfa zinc finger 1 (Alfin1), a root growth-associated transcription factor gene, Pennisetum glaucum heat-shock factor (PgHSF4) and Pea DNA helicase (PDH45) involved in protein turnover and protection showed improved tolerance, higher growth and productivity under drought stress conditions. Stable integration of all the transgenes was noticed in transgenic lines. The transgenic lines showed higher root growth, cooler crop canopy air temperature difference (less CCATD) and higher relative water content (RWC) under drought stress. Low proline levels in transgenic lines substantiate the maintenance of higher water status. The survival and recovery of transgenic lines was significantly higher under gradual moisture stress conditions with higher biomass. Transgenic lines also showed significant tolerance to ethrel-induced senescence and methyl viologen-induced oxidative stress. Several stress-responsive genes such as heat-shock proteins (HSPs), RING box protein-1 (RBX1), Aldose reductase, late embryogenesis abundant-5 (LEA5) and proline-rich protein-2 (PRP2), a gene involved in root growth, showed enhanced expression under stress in transgenic lines. Thus, the simultaneous expression of regulatory genes contributing for drought-adaptive traits can improve crop adaptation and productivity under water-limited conditions.

Stress Inducible Overexpression of AtHDG11 Leads to Improved Drought and Salt Stress Tolerance in Peanut (Arachis hypogaea L.)

“…The resulted phenotypic data clearly indicates that stress regulated expression of AtHDG11 is sufficient enough to obtain tolerant phenotype only under stress conditions, but not under ideal growth conditions. Analog phenotypes were observed in peanut transgenic carrying transgens under rd29A regulation (Kasuga et al, 2004 ; Bhatnagar-Mathur et al, 2007 ; Vadez et al, 2007 ; Devi et al, 2011 ; Jagana et al, 2012 ; Sarkar et al, 2014 ; Ramu et al, 2016 ).…”

“…Using the identified stress-responsive genes with putative regulatory roles (transcription factors) from the model plants to develop stress resilient crops has proven to be an efficient strategy compared to traditional breeding (Molinar, 2012 ; Basu et al, 2016 ). The effective use of transcription factors (TFs) for the development of stress-resilient peanut crop have already been witnessed in previous studies such as heterologous overexpression of individual TFs AtDREB1A (Bhatnagar-Mathur et al, 2007 ; Sarkar et al, 2016 ), MuNAC4 (Pandurangaiah et al, 2014 ), and simultaneous expression of AtDREB2A , AtHB7 , and AtABF3 (Pruthvi et al, 2014 ); Alfin1, PgHSF4 , and PDH45 (Ramu et al, 2016 ). Though drought and salt tolerance mechanisms share common genes, few genes were found specifically involve in salt tolerance.…”

DNA methylation as a possible mechanism affecting ability of natural populations to adapt to changing climate

“…First, We expected that DNA demethylation may modify species adaptation potential by activation of epigenetically silenced genes (Feng et al 2010) or transpositions of epigenetically silenced transposons (Reinders et al 2009, Johannes et al 2009, Griffin et al 2016. Both these mechanisms may, however, lead to both deactivation and activation of the genes promoting drought adaptation as effects of such genes depend on function of many other related genes (Golldack et al 2011, Ramu et al 2016. Thus, in contrast to our initial expectation that the genes related to drought adaptation get deactivated by demethylation, they may have become activated instead.…”

An Alfin-like gene from Atriplex hortensis enhances salt and drought tolerance and abscisic acid response in transgenic Arabidopsis

“…As transcription regulators, AL family should function through controlling the expression of different target genes. Alfalfa Alfin1 was first identified to regulate the expression of MsPRP2 gene which encodes a putative proline-rich cell wall protein and positively regulate plant salt and drought resistance 23 , 25 , 43 . Constitutive expression of GmPHD2 in Arabidopsis inhibited the expression of CBF2/DREB1C , STRS1 , STRS2 , SIS8 , and three other negative regulator genes.…”