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Arabidopsis thaliana nicotinate/nicotinamide mononucleotide adenyltransferase (AtNMNAT) is required for pollen tube growth
Author(s) -
Hashida Shinnosuke,
Takahashi Hideyuki,
KawaiYamada Maki,
Uchimiya Hirofumi
Publication year - 2007
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2006.02989.x
Subject(s) - nicotinamide mononucleotide , nad+ kinase , nicotinamide adenine dinucleotide , biochemistry , mutant , arabidopsis thaliana , pollen tube , biology , pollen , gene , chemistry , enzyme , botany , pollination
Summary While mammals and fungi possess nicotinate/nicotinamide mononucleotide adenyltransferase (NMNAT) isoforms, Arabidopsis thaliana only contains a single NMNAT gene, AtNMNAT (At5g55810). We analyzed the enzymatic activity of the AtNMNAT ‐encoded protein to determine the role of AtNMNAT in plant development. AtNMNAT catalyzed the synthesis of nicotinate adenine dinucleotide (NaAD) from nicotinate mononucleotide (NaMN) in the Preiss–Handler‐dependent pathway, and of nicotinamide adenine dinucleotide (NAD) from nicotiamide mononucleotide (NMN) in the Preiss–Handler‐independent pathway. Prominent AtNMNAT expression was detected in the male gametophyte. Moreover, AtNMNAT expression was spatio‐temporally regulated during microspore development and pollen tube growth. Disruption of the AtNMNAT gene ( atnmnat mutant) was characterized by a decrease in NAD content in pollen. Cytological examinations revealed that the atnmnat mutant was gametophytically impaired in in vivo and in vitro pollen tube growth. Our results suggest that metabolic fulfillment via the NAD pathway is indispensable for normal pollen growth and subsequent normal seed production.