Transcriptional reprogramming of genes related to bud dormancy, outgrowth, and hormones for tiller development due to drought preconditioning in Lolium perenne

Drought-preconditioned plants may recover quickly from mild stress upon rewatering, but the mechanisms of tiller regeneration from stressed plants are not well understood. The objective of this study was to elucidate the mechanism underlying the promotive effects of mild drought stress or drought preconditioning on tiller development during rewatering. Perennial ryegrass plants were subjected to three treatments: 1) well-watered control of plants irrigated regularly (W); 2) drought preconditioning of plants exposed to mild drought stress through the withholding of irrigation for 5 d and then rewatering for 3 d (D5 + W3), then withholding water for 5 d and rewatering for 11 d; or 3) by withholding irrigation for 13 d and rewatering for 11 d (D13 + W). Both bud initiation and outgrowth were accelerated in plants that underwent drought preconditioning (D5 + W3 treatment). Transcriptional profiling revealed an alteration in genes related to bud dormancy (LpDRM1 and LpARP), bud activity (LpPCNA and LpCycD2), axillary bud initiation (LpMOC1, LpLAX1, and LpLAX2), and bud outgrowth (LpTB1 and LpD3) in the crowns of the W-, D5 + W3-, and D13 + W-treated plants, suggesting that these factors played significant roles in the promotion of tiller bud initiation and outgrowth processes. In addition, abscisic acid (ABA), jasmonic acid (JA), and cytokinin (CK) participated in the enhancement of axillary bud initiation and outgrowth. This research enriched our knowledge of the mechanisms of drought preconditioning. The methods of water management employed in this study are of great importance for increasing crop production in circumstances of water shortage.