Abstract
Plant root systems are essential for the uptake of water and nutrients from soil and are positively correlated to yield in many crops including the sweetpotato, Ipomoea batatas (L.) Lam. Here, we isolated and functionally characterized IbRAP2.4, a novel nuclear-localized gene encoding the AP2/ERF transcription factor, from sweetpotato. IbRAP2.4 was responsive to NaCl, PEG8000, ethylene, and Indole 3-acetic acid treatments. As revealed by electrophoretic mobility shift assay and dual luciferase assay, IbRAP2.4 could bind to both DRE and GCC-box elements and acted as a transcription activator. IbRAP2.4 overexpression significantly promoted lateral root formation and enhanced the drought tolerance in Arabidopsis thaliana, while it inhibited storage root formation in transgenic sweetpotato by comprehensively upregulating lignin biosynthesis pathway genes. Results suggested that IbRAP2.4 may be a useful potential target for further molecular breeding of high yielding sweetpotato.
Highlights
Plants sense a wide array of stressors in their environment, including dehydration, which adversely affect their growth and yields
As the protein showed the highest similarity with AtRAP2.4 from Arabidopsis (At1g78080), which was classified into the DREB subfamily (Lin et al, 2008), we named it IbRAP2.4 (Figure 1A)
A phylogenetic tree was constructed with the amino acid sequences of IbRAP2.4 and DREB proteins from other plants
Summary
Plants sense a wide array of stressors in their environment, including dehydration, which adversely affect their growth and yields. To ensure plants’ survival in changing environments, root systems develop various adaptive traits governed through a complicated mechanism. Plant root systems develop from the root apical meristem initiated during embryogenesis and possibly from multiple non-root-borne adventitious root apical meristems (Motte et al, 2019). The model plant, Arabidopsis thaliana, has a tap-root system consisting of a central primary root and lateral roots (LRs), whereas several tuber and corm crops such as sweetpotato [Ipomoea batatas (L.) Lam.], IbRAP2.4 Affects Root Development develop an adventitious root system that emerges from diverse non-root organs after the embryonic stage (Belehu et al, 2004; Guan et al, 2019; Wei et al, 2019). The sweetpotato root system includes “thick” pigmented storage roots (SRs), “thick” pigmented pencil roots (PRs), and white fibrous roots (FRs) (Wilson and Lowe, 1973; Belehu et al, 2004)
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