Down‐regulation of plant V‐type H⁺‐ATPase genes after light‐induced inhibition of growth

Abstract

Cell extension growth in the mesocotyl tip of darkgrown Zea mays L. seedlings is dependent on vacuole enlargement and massive flux of ER and Golgi vesicles. Water flow into the expanding vacuole is driven by ion accumulation, which in turn is energized by the vacuolar H+-ATPase (V-ATPase). The V-ATPase energizes the secondary ion transport into the expanding vacuole. As light exposure leads to a strong inhibition of extension growth, the effect of light on transcript levels for subunits A and c of the V-ATPase was analyzed. Partial homologous cDNAs for subnnit A and two isoforms of snbunit c were cloned by RT-PCR. In dark-grown seedlings transcript levels for both subnnits were much higher in the growing mesocotyl tip than in the fully differentiated mesocotyl tissue. Only in the tip region did light exposure lead to a strong and coordinate down-regulation of both mRNAs whereas in the differentiated mesocotyl only a slight decrease was observed. The results indicate that expression of the 'housekeeping' V-type H +-ATPase is strongly regulated in response to growth rate. maize seedlings was chosen as a well defined experimental system. Here, elongation is the result of directional cell extension and is inhibited by light exposure [10][11][12]. In the etiolated seedling, cell division and elongation in the mesocotyl tip (5 mm) are dependent on intense traffic of ER and Golgi vesicles and vacuole expansion [13]. These processes are in turn dependent on luminal acidification by V-ATPase and, possibly, H---PPiase, which resides on the same membrane [14]. We have studied the expression of V-ATPase genes coding for the catalytic subunit A (part of the peripheral Vl-complex) and the proton channel forming subunit c (part of the membrane-integral Vo-complex) [1]. Transcript levels of both subunits were analyzed in the growing mesocotyl tip (0-5 mm) and the mesocotyl base (5-70 mm) of 6-day-old etiolated Zea mays seedlings before and after light exposure. The results indicate that expression of V-ATPase genes is strongly correlated with extension growth.

Energization of Plant Cell Membranes by H+-Pumping ATPases: Regulation and Biosynthesis

“…The expression of V o and V 1 subunits therefore appears to be coordinately regulated. Transcript levels of both subunit A and subunit c are downregulated in response to light, which inhibits growth of the mesocotyl (Viereck et al, 1996).…”

Salt stress induces an increased expression of V-type H+-ATPase in mature sugar beet leaves

“…1) [10,12]. At the DNA level identities with the corresponding partial cDNA sequences of subunit c from Daucus carota, Zea mays and Avena sativa were 82.5% (R. L6w, unpublished), 75.4% [26], and 74.6% [12], respectively. Southern blot analysis indicated the presence of at least two genes (Fig.…”

“…Based on northern blot analysis [14,15] Figure 1. Protein and DNA sequence of the partial eDNA of Beta vulgaris V-ATPase subunit c, and alignment with the corresponding DNA sequences from Avena sativa [ 12], Daucus carota (R. L6w, unpublished) and Zea mays [26]. The partial eDNA was cloned by RT-PCR [ 13, 15l The non-radioactive procedures are described [14,15].…”

“…3). A down-regulation of subunit c expression in mature non-growing leaves has been recently observed in M e s e m b r y a n t h e m u m crystallinum [ 13], and a correlation of subunit c expression with cell expansion growth has been reported for several plant species [10,13,19,26]. It follows that any stress-induced changes of subunit c expression in intact plants have to be related to plant development.…”

Plant regeneration andAgrobacterium-mediated transformation of Vacuolar H+-ATPase c Subunit Gene in hybrid poplarpopulus davidianaDode ×P. bollenaLauche

“…Vacuolar H + -ATPase c Subunit Gene (VHA-c) was isolated from Puccinellia chinampoensis, which was used to transformation in the study. Several researchs and informations about VHA have been published including structure, function and regulation mechanism [11][12][13][14]. Vacuolar H + -ATPase c Subunit Gene has been studied in Mesembryanthemum crystallinum [15], sugar beet [16], Arabidosis thaliana [17,18] and tobacco [19].…”