TY - JOUR
T1 - Post-transcriptional Regulation of FLOWERING LOCUS T Modulates Heat-Dependent Source-Sink Development in Potato
AU - Lehretz, Günter G.
AU - Sonnewald, Sophia
AU - Hornyik, Csaba
AU - Corral, José M.
AU - Sonnewald, Uwe
N1 - This research was part of
the ERA-CAPS HotSol project supported by grants from Deutsche Forschungsgemeinschaft (DFG) SO 300/20-1 to U.S. and SO 1002/3-1 to S.S.
Copyright © 2019 Elsevier Ltd. All rights reserved.
PY - 2019/5/20
Y1 - 2019/5/20
N2 - Understanding tuberization in the major crop plant potato (Solanum tuberosum L.) is of importance to secure yield even under changing environmental conditions. Tuber formation is controlled by a homolog of the floral inductor FLOWERING LOCUS T, referred to as SP6A. To gain deeper insights into its function, we created transgenic potato plants overexpressing a codon-optimized version of SP6A, SP6Acop, to avoid silencing effects. These plants exhibited extremely early tuberization at the juvenile stage, hindering green biomass development and indicating a tremendous shift in the source sink balance. The meristem identity was altered in dormant buds of transgenic tubers. This strong phenotype, not being reported so far for plants overexpressing an unmodified SP6A, could be due to post-transcriptional regulation. In fact, a putative SP6A-specific small regulatory RNA was identified in potato. It was effectively repressing SP6A mRNA accumulation in transient assays as well as in leaves of young potato plants prior to tuber formation. SP6A expression is downregulated under heat, preventing tuberization. The molecular mechanism has not been elucidated yet. We showed that this small RNA is strongly upregulated under heat. The importance of the small RNA was demonstrated by overexpression of a target mimicry construct, which led to an increased SP6A expression, enabling tuberization even under continuous heat conditions, which abolished tuber formation in the wild-type. Thus, our study describes an additional regulatory mechanism for SP6A besides the well-known pathway that integrates both developmental and environmental signals to control tuberization and is therefore a promising target for breeding of heat-tolerant potato.
AB - Understanding tuberization in the major crop plant potato (Solanum tuberosum L.) is of importance to secure yield even under changing environmental conditions. Tuber formation is controlled by a homolog of the floral inductor FLOWERING LOCUS T, referred to as SP6A. To gain deeper insights into its function, we created transgenic potato plants overexpressing a codon-optimized version of SP6A, SP6Acop, to avoid silencing effects. These plants exhibited extremely early tuberization at the juvenile stage, hindering green biomass development and indicating a tremendous shift in the source sink balance. The meristem identity was altered in dormant buds of transgenic tubers. This strong phenotype, not being reported so far for plants overexpressing an unmodified SP6A, could be due to post-transcriptional regulation. In fact, a putative SP6A-specific small regulatory RNA was identified in potato. It was effectively repressing SP6A mRNA accumulation in transient assays as well as in leaves of young potato plants prior to tuber formation. SP6A expression is downregulated under heat, preventing tuberization. The molecular mechanism has not been elucidated yet. We showed that this small RNA is strongly upregulated under heat. The importance of the small RNA was demonstrated by overexpression of a target mimicry construct, which led to an increased SP6A expression, enabling tuberization even under continuous heat conditions, which abolished tuber formation in the wild-type. Thus, our study describes an additional regulatory mechanism for SP6A besides the well-known pathway that integrates both developmental and environmental signals to control tuberization and is therefore a promising target for breeding of heat-tolerant potato.
KW - Base Sequence
KW - Gene Expression Regulation, Plant
KW - Hot Temperature
KW - Plant Proteins/genetics
KW - Plant Tubers/genetics
KW - Plants, Genetically Modified/genetics
KW - RNA, Plant/genetics
KW - Solanum tuberosum/genetics
U2 - 10.1016/j.cub.2019.04.027
DO - 10.1016/j.cub.2019.04.027
M3 - Article
C2 - 31056391
SN - 0960-9822
VL - 29
SP - 1614-1624.e3
JO - Current biology : CB
JF - Current biology : CB
IS - 10
ER -