Short tandem target mimic rice lines uncover functions of miRNAs in regulating important agronomic traits
Saturday, 2017/05/20 | 12:13:19
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Hui Zhang, Jinshan Zhang, Jun Yan, Feng Gou, Yanfei Mao, Guiliang Tang, José Ramón Botella, and Jian-Kang Zhu SignificancePlant microRNAs (miRNAs) control intricate gene regulatory networks and have been implicated in important developmental switches and stress responses. Plant miRNAs have recently emerged as promising targets for crop improvement because they can control complex agronomic traits; however, functional studies using reverse genetics have been hampered by practical difficulties. We have silenced 35 miRNA families in rice to generate a resource for discovering new functions of miRNAs and targets of agronomic improvements. As a proof of concept, we show that manipulation of a promising miRNA, miRNA398, leads to important yield improvements. Our findings also reveal important agronomic roles for several miRNAs. AbstractImprovements in plant agricultural productivity are urgently needed to reduce the dependency on limited natural resources and produce enough food for a growing world population. Human intervention over thousands of years has improved the yield of important crops; however, it is increasingly difficult to find new targets for genetic improvement. MicroRNAs (miRNAs) are promising targets for crop improvement, but their inactivation is technically challenging and has hampered functional analyses. We have produced a large collection of transgenic short tandem target mimic (STTM) lines silencing 35 miRNA families in rice as a resource for functional studies and crop improvement. Visual assessment of field-grown miRNA-silenced lines uncovered alterations in many valuable agronomic traits, including plant height, tiller number, and grain number, that remained stable for up to five generations. We show that manipulation of miR398 can increase panicle length, grain number, and grain size in rice. In addition, we discovered additional agronomic functions for several known miRNAs, including miR172 and miR156. Our collection of STTM lines thus represents a valuable resource for functional analysis of rice miRNAs, as well as for agronomic improvement that can be readily transferred to other important food crops.
See http://www.pnas.org/content/114/20/5277.abstract.html?etoc PNAS May 16 2017; vol.114; no.20: 5277–5282
Fig. 1. miR398 controls rice panicle and seed development and can be manipulated for rice improvement. (A) Gross morphologies of WT (Nipponbare) and STTM398 plants at maturity. (Scale bar, 10 cm.) (B) Panicle morphologies of WT and STTM398 plants. (Scale bar, 5 cm.) (C) Grain width of WT and STTM398 plants. (Scale bar, 1 cm.) (D) Grain length of WT and STTM398 plants. (Scale bar, 1 cm.) Plant height (E), main panicle length (F), grain number per panicle (G), and 1,000-grain weight (H) of WT and STTM398 plants are shown. (I) Expression levels of miR398 in WT and STTM398 plants detected using Northern blotting. U6 was used as a loading control. (J) Expression levels of miR398 predicted targets in WT and STTM398 plants determined by qRT-PCR. (K) Gross morphologies of WT, OX-miR398a, and mOs07g46990 plants at maturity. (Scale bar, 10 cm.) (L) Panicle morphologies of WT, OX-miR398a, and mOs07g46990 plants at maturity. (Scale bar, 5 cm.) Plant height (M), main panicle length (N), grain number per panicle (O), and 1,000-grain weight (P) of WT, OX-miR398a, and mOs07g46990 plants are shown. Data are presented as mean ± SD [n = 15 replicates in E and M; n = 30 replicates in F, G, N, and O; n = 10 (>120 seeds for each biological replicate) replicates in H and P; n = 3 in replicates in J]. *P < 0.05, **P < 0.01; two-tailed, two-sample t test. NS, not significant. |
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