Peas (Pisum sativum L.) with strain specificity for Rhizobium leguminosarum

Treatment of Pisum sativum (L.) cv. 'Sparkle' with ethyl methanesulfonic acid (EMS) produced a stable mutant, E135F, which forms small, white, ineffective nodules. These nodules exhibit histological zonation typical of an indeterminant nodule, e.g. meristematic, early symbiotic, late symbiotic, and senescent zones. Compared with the nitrogen fixing nodules of the parent, the zones are smaller and the nodules senesce prematurely. Bacteroids in E135F are less elongated and less differentiated than those in 'Sparkle.' The E135F mutant forms ineffective nodules when inoculated with nine different effective strains of Rhizobium leguminosarum and also when grown in a soil containing effective strains. The ineffective phenotype of E135F is under monogenic recessive control; the gene is designated sym 13. sym 13 was located on chromosome 2 by linkage with genes for shikimic dehydrogenase and esterase-2. The original selection E135F carried another mutation in heterozygous form at a separate locus, yielding some homozygous recessive nonnodulating progeny, E135N, in (14) with ineffective nodules have been discovered in breeding programs. In addition, ineffective lines of chickpea (Cicer arietinum L.) (1), faba bean (Vicia faba L.) (4), and pea (Pisum sativum L.) (3, 15) have been obtained by induced mutagenesis.This report describes an ineffective mutant of pea obtained

Section: Resultsmentioning

confidence: 99%

Section: Materials and Methods Plant Culturementioning

confidence: 99%

sym 13—A Gene Conditioning Ineffective Nodulation in Pisum sativum

Kneen¹,

LaRue²,

Hirsch³

et al. 1990

“…Sweet clover (Melilotus alba, U389) and soybean (Glycine max L. cv Ransom) were inoculated with R. meliloti strain 1021 and Bradyrhizobium japonicum strain 61A92, respectively. Plants were inoculated with rhizobia on planting or 2 DAP, and were subirrigated with nutrient solution containing 5 mM nitrate (10). Plants were grown under highpressure sodium vapor and metal halide lamps (550 ,umol m-2 s-' PPFD) in a 16/8 h, 20/150C light/dark regime.…”

Section: Methodsmentioning

confidence: 99%

Exogenous Ethylene Inhibits Nodulation of Pisum sativum L. cv Sparkle

Lee

LaRue²

1992

143

105

Exogenous ethylene inhibited nodulation on the primary and lateral roots of pea, Pisum sativum L. cv Sparkle. Ethylene was more inhibitory to nodule formation than to root growth; nodule number was reduced by half with only 0.07 ML/L ethylene applied continually to the roots for 3 weeks. The inhibition was overcome by treating roots with 1 gM Ag', an inhibitor of ethylene action.Exogenous ethylene also inhibited nodulation on sweet clover (Melilotus alba) and on pea mutants that are hypernodulating or have ineffective nodules. Exogenous nodulation of intact plants seemed warranted, testing it on young plants at the stage when nodules are initiated.We have been using the pea cv Sparkle and a family of its near-isogenic symbiosis mutants to study the formation and function of nodules (3,8). In mutants at sym-5, there are few cortical cell divisions or nodule primordia in advance of the infection thread. However, nodules form (3, 7) if the roots are treated with inhibitors of ethylene formation (AVG)2 (16) or action (Ag+) (2). Another pea mutant E107 (brz) takes up excess ions and forms few nodules. Its nodule number is increased, though not to normal, by treatment of roots with Ag+ (8). Thus, ethylene may be involved in decreasing nodulation of these mutants. Similarly, the inhibition of nodulation by light may be mediated by ethylene (13).In this report, we establish that nodulation of intact plants is extremely sensitive to low concentrations of exogenous ethylene applied during the time of nodule initiation. We also determine the developmental stage at which exogenous ethylene inhibits nodule development on pea. MATERIALS AND METHODSSeeds were planted individually in coarse vermiculite in conical pots ('conetainers') that had 16 small holes in the upper 10 cm. Pea (Pisum sativum) cv Sparkle, its mutant line E135F (11), cv Rondo, and its mutant line nod-3 (9) were inoculated with Rhizobium leguminosarum bv. viciae strain 128C53. Sweet clover (Melilotus alba, U389) and soybean (Glycine max L. cv Ransom) were inoculated with R. meliloti strain 1021 and Bradyrhizobium japonicum strain 61A92, respectively. Plants were inoculated with rhizobia on planting or 2 DAP, and were subirrigated with nutrient solution containing 5 mM nitrate (10). Plants were grown under highpressure sodium vapor and metal halide lamps (550 ,umol m-2 s-' PPFD) in a 16/8 h, 20/150C light/dark regime.For treatment with exogenous ethylene, conetainers were placed in 10-L chambers so that the roots were continually exposed to air containing ethylene (12). Air was scrubbed of ethylene by passage through Purafil (Purafil Inc., Atlanta, GA) and pumped to a four-outlet manifold. To three of the outlets, ethylene was added via micro valves (Nupro Co. Plant Physiol. Vol. 100, 1992 At harvest, nodules on the upper 10-cm region of pea roots and on whole roots of sweet clover and soybean were counted. The length of the primary and the longest lateral roots, and the dry weight of roots and shoots were also recorded. In some trials, the upperm...

“…Unless otherwise stated, seeds were individually planted in coarse vermiculite in various sizes of conical pots ('Conetainers'; Ray Leach Conetainer Nursery, Canby, OR) and subirrigated with nutrient solution containing 5 mn-m NO3- (9). When necessary, plants were inoculated at planting with R. leguminosarum strain 128C53 (Nitragin Co., Milwaukee, WI) grown as described previously (9 …”

Section: Plant Culturementioning

confidence: 99%

“…When necessary, plants were inoculated at planting with R. leguminosarum strain 128C53 (Nitragin Co., Milwaukee, WI) grown as described previously (9 …”

Section: Plant Culturementioning

confidence: 99%

Pleiotropic Effects of sym-17

Lee¹,

LaRue²

1992

R82 (sym-1 7), a stable mutant of Pisum sativum L. cv Sparkle, is described. The shoot growth of the mutant was less than that of its parent under light or dark growth conditions. Gibberellic acid treatment did not normalize the shoot growth of R82. The mutant had thick and short roots. It formed few nodules, but the specific nitrogenase activity was not affected. R82 produced and contained more ethylene than Sparkle. It also contained more free 1-aminocyclopropane-1-carboxylic acid than did its parent in both the shoot and the root. The root tip of R82 had a lower activity of ethylene-forming enzyme than that of Sparkle, whereas the whole shoot of R82 had a similar activity. The sensitivity of R82 to exogenous ethylene was not more than that of Sparkle. Exogenous ethylene treatments did not make Sparkle mimic R82, and inhibitors of ethylene biosynthesis or action did not normalize the phenotype of R82. The data suggest that the primary effect of sym-17 is not the enhanced ethylene production.