Infection and Root-Nodule Development in<i>Stylosanthes</i>Species by<i>Rhizobium</i>

Chandler, Muriel R.; Date, R. A.; Roughley, R. J.

doi:10.1093/jxb/33.1.47

Cited by 119 publications

(66 citation statements)

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“…In S. rostrata, root nodule meristems are induced simultaneously with infection in middle and inner cortical cell layers. Thus, for this tropical legume, root nodules originate at the same histological level as indeterminate nodules of temperate legumes (11,19,26,34,36) and not from the root outer cortex, as for most tropical legumes (2,6,7,26,39). Moreover, by showing that nodule meristematic centers can be detected during the very first hours following inoculation, before infection has progressed beyond the outermost plant cells, our results suggest that the meristem is induced at a distance (35,36).…”

Section: Discussionsupporting

confidence: 51%

“…In legumes such as Arachis hypogaea and Stylosanthes spp., microsymbionts infect their hosts by "crack entry," i.e., intercellularly between adjacent cells without the formation of infection threads (1,6,7,33). In other tropical legumes, such as Glycine max (26,39), the infection process proceeds as in temperate legumes, i.e., by the formation of infection threads through root hairs.…”

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confidence: 99%

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Root nodulation of Sesbania rostrata

et al. 1994

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The tropical legume Sesbania rostrata can be nodulated by Azorhizobium caulinodans on both its stem and its root system. Here we investigate in detail the process of root nodulation and show that nodules develop exclusively at the base of secondary roots. Intercellular infection leads to the formation of infection pockets, which then give rise to infection threads. Concomitantly with infection, cortical cells of the secondary roots dedifferentiate, forming a meristem which has an "open-basket" configuration and which surrounds the initial infection site. Bacteria are released from the tips of infection threads into plant cells via "infection droplets," each containing several bacteria. Initially, nodule differentiation is comparable to that of indeterminate nodules, with the youngest meristematic cells being located at the periphery and the nitrogen-fixing cells being located at the nodule center. Because of the peculiar form of the meristem, Sesbania root nodules develop uniformly around a central axis. Nitrogen fixation is detected as early as 3 days following inoculation, while the nodule meristem is still active. Two weeks after inoculation, meristematic activity ceases, and nodules then show the typical histology of determinate nodules. Thus, root nodule organogenesis in S. rostrata appears to be intermediate between indeterminate and determinate types.

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Section: Discussionsupporting

confidence: 51%

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confidence: 99%

Root nodulation of Sesbania rostrata

et al. 1994

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“…However, the anomalous nodulation of subterranean clover by R. leguminosarum 1020 differs from other modes of rhizobial infection with Arachis hypoguea (Allen & Allen, 1940;Chandler, 1978), Stylosanthes spp. (Ranga Rao, 1977 ;Chandler et al, 1982) and Aeschynomene indica (Arora, 1954) where infection threads have not been found in the root hairs or nodules. Also, a R .…”

Section: Discussionmentioning

confidence: 99%

Characterization of the Anomalous Infection and Nodulation of Subterranean Clover Roots by Rhizobium leguminosarum 1020

Hrabak

Truchet

Dazzo³

et al. 1985

Microbiology

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Anomalous nodulation of Trifblium subterraneum (subterranean clover) roots by Rhizobium leguminosarum 1020 was examined as a model of modified host-specificity in a Rhizobiumlegume symbiosis. Consistent with previous reports, these nodules (i) appeared most often at sites of secondary root emergence, (ii) were ineffective in nitrogen fixation and (iii) were as numerous as nodules formed by an effective Rhizobium trifolii strain. R. leguminosarum 1020, grown on agar plates or in the clover root environment, did not bind the white clover lectin, trifoliin A. This strain did not attach in high numbers, and did not induce shepherd's crooks or infection threads, in subterranean clover root hairs. However, R . leguminosarum 1020 did cause branching, moderate curling and other deformations of root hairs. The bacteria probably entered the clover root through breaks in the epidermis at sites of lateral root emergence. The anomalous nodulation was inhibited by nitrate. Only trace amounts of leghaemoglobin were detected in the nodules by Western blot analysis. The nodules were of the meristematic type and initially contained well-developed infection, bacteroid and senescent zones. Infection threads were readily found in the infection zone of the nodule. However, the bacteroid-containing tissue senesced more rapidly than in the effective symbiosis between subterranean clover and R. trifolii 0403. This anomalous nodulation of subterranean clover by R. leguminosarum 1020 suggests a naturally-occurring alternative route of infection that allows Rhizobium to enlarge its host range.

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“…In other legumes, such as Aeschynomene sp and Stylosanthes sp, rhizobia move through the cortex intercellularly. During this process, they induce the collapse of cortical cells, leading to the formation of an "infection strand," which the bacteria use to reach the primordium (Chandler et al, 1982;de Faria et al, 1988;Alazard and Duhoux, 1990). The collapse of cortical cells shows that the bacteria display characteristics of pathogens in this phase of the interaction.…”

Section: Lnfectionmentioning

confidence: 99%

“…During intercellular infection, rhizobia can penetrate through the gaps in the epidermis that can form where lateral roots or adventitious roots emerge from the main root or the stem, respectively (Chandler et al, 1982;James et al, 1992). This…”

Section: Intercellular Infectionmentioning

confidence: 99%