A Lipid Transfer Protein Variant with a Mutant Eight-cysteine Motif Causes Photoperiod-thermo-sensitive Dwarfism in Rice.
Plant height is an important trait for plant architecture patterning and crop yield improvement. Although the pathways involving in gibberellins and brassinosteroid have been well studied, there are still many gaps in the picture of the networks controlling plant height. Here, we revealed that a dominant photoperiod- and thermo-sensitive dwarf mutant is caused by the active role of a mutated gene Ptd1, of which the wild-type gene encodes a non-specific lipid transfer protein (nsLTP). The Ptd1 plants showed severe dwarfism under long-day and low-temperature conditions, but grew nearly normal under short-day and high-temperature conditions; these phenotypic variations were associated with the Ptd1 mRNA level and its protein accumulation. Furthermore, we found that the growth inhibition in Ptd1 might result from the special protein conformation of Ptd1 due to loss of two disulfide bonds in the Eight-cysteine motif (8-CM) that is conserved among nsLTPs. Our findings give new insights into the understanding of the novel function of disulfide bonds in 8-CM, and provide a new strategy for regulation of cell development and plant height, by modifying the amino acid residues involved in protein conformation patterning.