Knock-down the expression of TaH2B-7D using virus-induced gene silencing reduces wheat drought tolerance

Abstract

Background: Drought is a major abiotic stress affecting global wheat (Triticum aestivum L.) production. Exploration of drought-tolerant genes is essential for the genetic improvement of drought tolerance in wheat. Previous studies have shown that some histone encoding genes are involved in plant drought tolerance. However, whether the H2B family genes are involved in drought stress response remains unclear.

Methods: Here, we identified a wheat histone H2B family gene, TaH2B-7D, which was significantly up-regulated under drought stress conditions. Virus-induced gene silencing (VIGS) technology was used to further verify the function of TaH2B-7D in wheat drought tolerance. The phenotypic and physiological changes were examined in the TaH2B-7D knock-down plants.

Results: In the TaH2B-7D knock-down plants, relative electrolyte leakage rate and malonaldehyde (MDA) content significantly increased, while relative water content (RWC) and proline content significantly decreased compared with those in the non-knocked-down plants under drought stress conditions. TaH2B-7D knock-down plants exhibited severe sagging, wilting and dwarf phenotypes under drought stress conditions, but not in the non-knocked-down plants, suggesting that the former were more sensitive to drought stress.

Conclusion: These results indicate that TaH2B-7D potentially plays a vital role in conferring drought tolerance in wheat.

Keywords: Drought; Knock-down; TaH2B-7D; Triticum aestivum L..

Fig. 1

Relative expression level of TaH2B-7D under drought stress, low nitrogen and salt stress conditions. a, b drought stress; c, d low nitrogen stress; e, f salt stress. a, c, e Real-time PCR analysis of TaH2B-7D using TaActin as reference gene. b, d, f Real-time PCR analysis of TaH2B-7D using TaActin as reference gene. NS non-stress; DS drought stress; LN low nitrogen; SS salt stress. Each bar shows the mean ± standard errors (SE). Double asterisk indicate significant differences at P ≤ 0.01 levels

Fig. 2

Detection of the expression levels of TaH2B-7D in the gene knock-down and control plants. NS, non-stress; DS, drought stress. BSMV₀, negative control of the VIGS system; BSMV_TaH2B-7D, TaH2B-7D-knock down plants; BSMV_TaH2B-7D-1, BSMV_TaH2B-7D-2, BSMV_TaH2B-7D-3 and BSMV_TaH2B-7D-4 are four independent TaH2B-7D-knock down plants. The expression level of TaH2B-7D in the TaH2B-7D-knock down plants was detected under DS conditions. Different letters above the columns indicate significant differences at P ≤ 0.01 levels

Fig. 3

The phenotypes of TaH2B-7D-knock down plants. a Leaf; b, c whole plants; b non-stress treatment (NS); c drought stress treatment (DS). BSMV₀ represents the negative control of VIGS system; BSMV_PDS represents the positive control monitoring time course of VIGS; BSMV_TaH2B-7D represents TaH2B-7D-knock down plants

Fig. 4

The changes in the physiological indices of the TaH2B-7D-knock-down plants. a Relative water content; b rate of relative electrolyte leakage; c MDA content; d proline content. NS, non-stressed plants; DS, drought-stressed plants; BSMV₀, negative control of the VIGS system; BSMV_TaH2B-7D, TaH2B-7D-knock-down plants. Each bar shows the mean ± standard errors (SE) for three biological replicates