Isolation and characterization of three families of auxin down-regulated cDNA clones

Abstract

Five cDNA clones (ADR6, ADR11-1, ADR11-2, ADR12-1 and ADR12-2), representing three families of auxin down-regulated (ADR) genes were isolated and characterized. These were isolated by screening a lambda Zap cDNA library with the partial cDNA clones p6, p11 and p12, isolated earlier (Baulcombe and Key, J Biol Chem 255: 8907-8913, 1980). Hybrid-select translation of ADR6, ADR11-2 and ADR12-2 clones produced polypeptides of 33 kDa 22.5 kDa and a 6 and 7 kDa respectively, when analyzed by SDS-PAGE. ADR6 and ADR12-2 gave one and two spots, respectively, on an IEF-SDS 2D gel. ADR11-2 probably encodes a basic protein as it was only resolved on non-equilibrium pH gradient gel electrophoresis (NEPHGE). Genomic Southern blot analysis of ADR6, ADR11 and ADR12 suggests that each represents a small multigene family. The RNA levels corresponding to ADR6, ADR11 and ADR12 decrease in response to applied auxin by 100-, 15- and 10-fold, respectively (Baulcombe and Key, 1980). Runoff transcription, done in the presence and absence of auxin, showed that the rate of transcription of the genes corresponding to ADR6, ADR11-2 and ADR12-2 was reduced in the presence of auxin, but the decrease was small relative to the decrease in the cytoplasmic levels of these mRNAs, in response to auxin. A comparative analysis of the influence of auxin on in vitro transcription and steady state RNA levels corresponding to these ADR cDNAs suggests that the decrease in rate of transcription due to auxin is not enough to account for the auxin-induced decrease in the steady state levels. Northern analysis showed developmental and organ/tissue-specific response of these ADR genes. Furthermore, the expression of the genes corresponding to ADR6 and ADR12-1 appears to be up-regulated by light, whereas the gene corresponding to ADR11 appears to be down-regulated by light.

Clustering of Microarray Data Reveals Transcript Patterns Associated with Somatic Embryogenesis in Soybean,

“…The timing of their increase (14 d for leginsulin or 21 d for the others) in the adaxial side coincides with the decline in abundance of transcripts associated with oxidative stress, a time when the availability of reducing thiol compounds such as glutathione might become less important, and sulfur reserves can be replenished. The clustering of Bowman-Birk and leginsulin genes with ADR12-2, a small polypeptide characterized by its negative regulation by auxin (Datta et al, 1993), suggests that they might be down regulated by auxin or the ensuing oxidative burst and is consistent with our hypothesis.…”

“…This suggest that in soybean, the beginning of embryogenesis (up to the globular phase) can occur on auxin, but as in other systems the expression of the genes associated with embryogeesis might be delayed until partial depletion of auxin in the medium (after 14 d). The hypothesis of a depletion of the medium in auxin overtime is supported by the decrease in mRNA abundance between 7 and 14 d of GH1 and Monopteros, two genes participating in the auxin response (Guilfoyle et al, 1993;Ulmasov et al, 1997) and by the increase in steady-state RNA of the auxin down-regulated gene ADR12-2 (Datta et al, 1993) between 14 and 21 d and 21 and 28 d (Table III).…”

The classical Ubisch bodies carry a sporophytically produced structural protein (RAFTIN) that is essential for pollen development

“…12 A) and Ͼ90% identical to ESTs from inflorescences of various cereal species. All other significant ''hits'' (E value of Ͻ10 Ϫ4 ) were also only from plant accessions, but generally they had only Ϸ35% identity and included the following BURP domain proteins (29): a seed protein of faba bean (30); the ␤ subunit of polygalacturonase isoenzyme 1 from the developing fruit of tomato (31); an desiccation-induced protein of Arabidopsis (32); an auxin down-regulated protein (33) and an aluminum up-regulated protein (34) from soybean hypocotyl and roots, respectively; microspore embryo development-related protein from Brassica napus (29); an apomixisspecific gene product from the flower buds of guinea grass (35) that showed Ϸ45% aa sequence identity over the entire carboxydomain; and a seed coat protein found in developing soybean seed coats (36).…”

β-Alanine N-Methyltransferase of Limonium latifolium. cDNA Cloning and Functional Expression of a Novel N-Methyltransferase Implicated in the Synthesis of the Osmoprotectant β-Alanine Betaine

“…4B). Genes that are up-regulated by light and downregulated by auxin are known in other plants (Datta et al, 1993). Further studies on the physiological significance of this regulation are in progress.…”