Mutations affecting nodulation in grain legumes and their potential in sustainable cropping systems

Bhatia, C.R. and Nichterlein, K. and Maluszynski, M. (2001) Mutations affecting nodulation in grain legumes and their potential in sustainable cropping systems. Euphytica, 120 (3). pp. 415-432.

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Abstract

Many spontaneous and a large number of induced mutants that show altered nodulation patterns have been isolated in pea, soyabean, common bean, faba bean, chickpea, groundnut and pigeon pea. Available information on nodulating mutants in these crops is summarized. The importance of nodulation mutants in basic studies on plant-microbe symbiotic interactions, nitrogen fixation and breeding of cultivars with higher yield and nitrogen fixation rate are examined. The nodulation mutants, after inoculation with specific bacterial strains or a number of different strains, exhibited any of the following: no nodulation (nod-), few nodules (nod+/-), ineffective nodulation (fix-), hypernodulation (nod++) or hypernodulation even in the presence of otherwise inhibitory nitrate levels (nts). No spontaneous hypernodulation or nts mutants have been found, all have been induced in independent experiments using different cultivars of pea, soyabean and common bean after mutagenizing the seeds. Most nodulation mutants showed monogenic recessive inheritance, though semi-dominant and dominant inheritance is also reported. Nodule number is controlled by a process known as autoregulation: hypernodulating mutants showed relaxed autoregulation. By grafting shoots of hypernodulating soyabean mutants on normal nodulating soyabean, mung bean and hyacinth bean, presence of a common, translocatable signal has been shown. Nodulation mutants have contributed to the understanding of the genetic regulation of host-symbiont interactions, nodule development and N fixation. Initially, the hypernodulating mutants had poor yields. Using the induced hypernodulating mutant, a new soyabean cultivar 'Nitrobean 60', has been released in Australia. This cultivar is reported to have given 15% higher yield over cv. Bragg, and contributed a higher amount of fixed N to the cereal crops in rotation. Prospects of using the nodulation mutants in developing grain legume cultivars that combines high yield with high residual N within the bioenergetic constraints, for developing sustainable cropping systems are examined.

Item Type: Article
Uncontrolled Keywords: Inheritance, Nodulation mutants, Nitrogen fixation, Symbiotic interaction
Author Affiliation: Plant Breeding and Genetics Section, Joint FAO/IAEA Division, Austria.
Subjects: Plant Production
Crop Improvement
Divisions: Chickpea
Common Bean
Groundnut
Pigeonpea
Depositing User: Mr Arbind Seth
Date Deposited: 19 Feb 2013 14:35
Last Modified: 19 Feb 2013 14:35
Official URL: http://dx.doi.org/10.1023/A:1017550319206
URI: http://eprints.icrisat.ac.in/id/eprint/9615

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