MS-desi, a desiccation-related protein in the floral nectar of the evergreen velvet bean (Mucuna sempervirens Hemsl): molecular identification and characterization

Abstract

Plant desiccation-related proteins (DRPs) were first identified as pcC13-62 from the resurrection plant Craterostigma plantagineum and it has been suggested they are involved in plant desiccation tolerance. We identified and characterized a plant DRP, which we called MS-desi, in the floral nectar of a subtropical bean species, Mucuna sempervirens (MS). MS-desi is a major nectar protein (nectarin) of the bean plant and expresses exclusively in the stylopodium, where the nectary is located. The full-length MS-desi gene encodes for a protein of 306 amino acids with a molecular mass of 33,248 Da, and possesses a ferritin-like domain and a signal peptide of 30 amino acids. Structural and phylogenetic analysis demonstrated MS-desi has high similarity to members of the plant DRPs, including pcC 13-62 protein. MS-desi has a similar hydropathy profile to that of pcC13-62 with a grand average of hydropathy index of 0.130 for MS-desi and 0.106 for pcC13-62 protein, which is very different from those of dehydrins and late embryogenesis abundant proteins. The protein's secondary structures, both predicted from the amino acid sequence and directly analysed by far UV circular dichroism, showed that MS-desi is mainly composed of alpha helices and is relatively temperature dependent. The structure change is reversible within a wide range of temperatures. Purified MS-desi and raw MS floral nectar showed dose-dependent citrate synthase inhibition activity, but insensitivity to lactate dehydrogenase, suggesting that, unlike dehydrins, it does not act as a chaperone. The overall results constitute, to our knowledge, the first study on a desiccation-related protein in plant floral nectar.

LEA polypeptide profiling of recalcitrant and orthodox legume seeds reveals ABI3-regulated LEA protein abundance linked to desiccation tolerance

“…Furthermore, two desiccation-related polypeptides (spots 82 and 88) were detected with homology to Lb_13-62 and PCC13-62. These genes are up-regulated in the desiccation-tolerant resurrection plants Craterostigma plantagineum and Lindernia brevidens (Phillips et al , 2008) and were also recently detected in floral nectar of the evergreen velvet bean ( Mucuna sempervirens Hemsl) (Zha et al , 2013). …”

Quantitative proteomic analysis of Araucaria angustifolia (Bertol.) Kuntze cell lines with contrasting embryogenic potential

“…The second protein that did not fall within a select functional group has sequence homology to plant desiccation-related proteins (pcc 13-62), which have been implicated in processes related to cell water availability [96]. Pcc 13-62 was first identified in the resurrection plant Craterostigma plantagineum [97], and is normally found in plants subjected to dehydration [98], or during late stages of seed development [99].…”

Peer Review #1 of "Different expression pattern of flowering pathway genes contribute to male or female organ development during floral transition in the monoecious weed Ambrosia artemisiifolia L. (Asteraceae) (v0.2)"

“…The homolog of desiccation-related protein, GO:no terms) showed the highest RPKM value, 1126.37, which is activated during the drought stress in the pollen, seeds, and vegetative organs in succulent plants (Giarola V et al 2018). It was expressed exclusively in the stylopodium of the hermaphrodite flower in Mucona sempervivens, where the nectary is located (Zha H-G et al 2013). Since the male flower pistillodium is a modified pistil with a function to help dispensing the pollen from staminate flowers in A. artemisiifolia (Payne WW 1963), the anatomical presence of this transcript may be explained.…”