Water-wise responses in the shoot meristem region of rice

REYNOSO MAURICIO ALBERTO; ENDANG SEPTININGSIH; GERMAIN PAULUZZI; MATT PRIOR; YUYA LIANG; JULIA BAILEY-SERRES; MIGUEL A. LOPEZ; SEAN CABANLIT; ALEK KETTENBERG

Conferencia; Plant Biology 2019; 2019

American Society of Plant Biologists

The cultivation of rice in rain-fed lowlands accounts for ~30% of world rice production. Paddy rice often endures too little or too much water due to climatic extremes, leading to yield instability. Through international efforts, beneficial genes of traditional landraces have been identified that enable rice to be seeded directly underwater to limit weed competition or to tolerate full submergence during vegetative development. One of these genes, SUBMERGENCE1A (SUB1A), provides metabolic and developmental plasticity that increases yield stability. The ethylene responsive transcription factor SUB1A maintains viability by limiting GA-promoted leaf elongation during submergence and by ROS production and dehydration upon desubmergence. Rice that is transiently submerged or water deprived can recover as long as axillary (tiller) meristems remain viable. SUB1A can significantly increases re-establishment through tiller growth after a sub-lethal water extreme. This motivated us to explore the impact of submergence and water-deficit on gene regulation within the shoot tip of rice. For non-Sub1 rice, we used INTACT (Isolation of Nuclei TAgged in specific Cell Types) and TRAP (Translating Ribosome Affinity Purification). We profiled chromatin accessibility, nuclear RNA and the translatome of cells defined by three promoters: CaMV 35S (near-constitutive), RSS1 (dividing cells), OSH1 (vegetative meristem). We also monitored the shoot tip transcriptome in near-isogenic lines varying at SUB1A in an indica and japonica variety. The results expose significant (i) regulation at the chromatin, transcriptional and posttranscriptional levels, (ii) distinctions between water extreme responses in genes associated with metabolism and cell division, and (iii) a general resilience of the shoot meristem region based on a rapid return to homeostasis. Funded by NSF IOS-1238243, IOS-1810468 and USDA NIFA 2017-67013-26194.