NtKRP, a kinesin-12 protein, regulates embryo/seed size and seed germination via involving in cell cycle progression at the G2/M transition

Abstract

Kinesins comprise a superfamily of microtubule-based motor proteins involved in essential processes in plant development, but few kinesins have been functionally identified during seed development. Especially, few kinesins that regulate cell division during embryogenesis have been identified. Here we report the functional characterization of NtKRP, a motor protein of the kinesin-12 family. NtKRP is predominantly expressed in embryos and embryonic roots. NtKRP RNAi lines displayed reductions in cell numbers in the meristematic zone, in embryonic root length, and in mature embryo and seed sizes. Furthermore, we also show that CDKA;1 binds to NtKRP at the consensus phosphorylation sites and that the decreased cell numbers in NtKRP-silenced embryos are due to a delay in cell division cycle at the G2/M transition. In addition, binding between the cargo-binding tail domain of NtKRP and CDKA; 1 was also determined. Our results reveal a novel molecular pathway that regulates embryo/seed development and critical role of kinesin in temporal and spatial regulation of a specific issue of embryo developmental.

Ribosomal protein NtRPL17 interacts with kinesin-12 family protein NtKRP and functions in the regulation of embryo/seed size and radicle growth

“…NtKRP was located in the cytoplasm and NtRPL17 was both in the cytoplasm and nucleus. CDKB1-1 is a nuclear and cytoplasmic protein ( Boruc et al , 2010 ; Tian et al , 2016 ). SPYCE-NtKRP, SPYNE-NtRPL17, co-expression combinations of SPYCE-NtKRP+SPYNE-CDKB1-1 and SPYNE-NtRPL17+the empty vector SPYCE were used as negative controls.…”

“…The paraffin blocks were cut into 8 µm thick sections. The reaction results of in situ hybridization signals were detected as a dark purple color by adding the substrates nitroblue tetrazolium/5-bromo-4-chloro-3-indolyl-phosphate (NBT/BCIP) ( Tian et al , 2016 ). The hybridization signals were observed with an OLYMPUS IX71 microscope.…”

“…SGL, (short grain length), a kinesin-like protein, regulates grain length and plant height in rice ( Wu et al , 2014 ). In our previous study ( Tian et al , 2016 ), a novel member of the kinesin-12 subfamily, NtKRP, was isolated from Nicotiana tabacum , which was shown to be expressed in tissues with actively dividing cells and in embryos at different developmental stages. We revealed that NtKRP plays a vital role in both cell cycle progression and cell expansion in embryonic and postembryonic development.…”

Genome wide analysis of kinesin gene family in Citrullus lanatus reveals an essential role in early fruit development

“…They play critical roles in the unidirectional transport of vesicles and organelles, cytokinesis, signal transduction, morphogenesis, cell division and cell growth in the plant development [40][41][42][43]. Furthermore, previous researches have revealed that the kinesin family genes also participated in plant reproductive development [29][30][31]44]. Especially, kinesin family genes have been proved to be essential for the regulation of early fruit development in Malus domestica and Cucumis sativus [15,17].…”

“…Moreover, other kinesin genes have been veri ed to possess different biological functions, including root, stem and leaf various vegetative tissues development genes (e.g., DBS1, BC12/GDD1, AtKINESIN-4A/FRA1) [25][26][27][28]; plus anther, male gametophyte, embryo, endosperm and seed development genes ( e.g., SRS3 and NtKRP) [29][30][31]. These works revealed the critical roles of plant kinesins in many essential processes in plant development, including not only plant vegetative growth but also plant reproductive process.…”