The present invention includes modified Arabidopsis Nucleoside
Di-Phosphate Kinase 2 (NDPK2) nucleic acid molecules whose enzymatic
activity have been increased (i.e. hyperactive). NDPKs are ubiquitous
housekeeping enzymes that catalyze the transfer of .gamma.-phosphoryl
group from a nucleoside triphosphate (NTP) to a nucleoside diphosphate
(NDP), and also multifunctional proteins that regulate a variety of
eukaryotic cellular activities, including cell proliferation,
development, and differentiation. In plants, NDPKs are reported to play a
key role in the signaling of both stress and light. Among three NDPKs
(NDPK1, NDPK2, NDPK3) in a model plant, Arabidopsis thaliana, NDPK2 was
reported as a positive signal transducer of phytochrome-mediated plant
light signaling and to regulate cellular redox state, which enhances
multiple stress tolerance in transgenic plants. Thus, the plants with the
hyperactive NDPK2 are expected to possess higher efficiency of light
utilization and enhanced tolerance to various environmental stresses such
as cold, salt, and oxidative stresses. Since abiotic stress is one of the
most important factors to limit the productivity of many crops, the
hyperactive NDPK2 can be used for the development of high-yielding
multiple stress tolerant plants with higher efficiency of light
utilization. In this invention, several hyperactive NDPK2 were generated
by C-terminal deletion and site-directed mutagenesis. Therefore, the
present invention can be utilized to develop multiple stress tolerant and
efficiently light-utilizing plants, which can eventually increase crop
yields. The invention also includes plants having at least one cell
expressing the modified NDPK2, vectors comprising at least one portion of
the modified NDPK2 nucleic acids, and methods using such vectors for
producing plants with enhanced light sensitivity and stress tolerance.