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Wheat Information Service
Number 78: 21-23 (1994)


Identification of chlorophyll synthetic genes in three hexaploid wheat varieties

Dalmir Singh

Division of Genetics, Indian Agricultural Research Institute, New Delhi - 110012, India


Summary

Chromosome 3A of an Indian hexaploid wheat var. Pb. C591 carries a gene for chlorophyll synthesis (Singh and Joshi 1979). In the present study, F2 segregation of green and albino seedlings was studied in crosses between Pb. C591 monosomic 3A (female) and varieties Kundan, Oligo and Rht-8 (male). Two dominant genes in Oligo and Rht-8 and one in Kundan regulated chlorophyll synthesis. One of the two genes in Oligo and Rht-8 and a single gene in Kundan were located on chromosome 3A.


Introduction

Austin et al. (1986) reported a high rate of photosynthesis (Pmax) in the flag leaves of diploid species of wheat. Necessity of identification of genes controlling Pmax in diploid, tetraploid and hexaploid species and their transfer to hexaploid wheats have been suggested. Since chlorophyll content has been implicated in Pmax, it becomes necessary to identify chlorophyll synthetic gene(s) in both donor as well as in recipients to facilitate their effective and selective transfer. In the present study we identified chlorophyll synthetic genes in three hexaploid wheat varieties.


Materials and methods

A variety Pb. C591 carries one gene or gene complex for chlorophyll synthesis that is located on chromosome 3A (Singh and Joshi 1979). In the selfed progenies of Pb. C591 monosomic 3A, Joshi et al. (1979) observed an unusally high frequency of nullisomics (12.0%) manifested as albino seedilings. To facilitate the identification of chlorophyll synthetic gene(s), monosornic 3A of Pb. C591 (female) was crossed with the varieties Kundan, Oligo and Rht-8. The F1 hybrids were cytologically examined at first meiotic metaphase to determine the chromosome constitution. At maturity, F2 seeds were taken from all the hydrids separately. Seeds were germinated in petridishes for observing the seedling traits.


Results and discussion

At 8th day after imbibition, seedlings were second for the presence of chlorophyll in the F2 progenies obtained after crosses of monosomic 3A (Pb. C591) x three varieties. Data pertaining to the frequency of albino seedlings recorded (Table 1). All the disomic plants (2n = 42) from selfed monosomic 3A produced only green seedlings, while the monosomic plants (2n = 41) gave an albino frequency of 12.3%.

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