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Wheat Information Service
Number 73: 30-32 (1991)

Identification and location of chlorophyll synthetic genes in a wheat variety Mara

Dalmir Singh

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


Summary

A study was undertaken to identify and locate gene(s) for chlorophyll synthesis on specific chromosomes in an Italian hexaploid dwarf wheat variety Mara. For this purpose a variety Mara was crossed as a male parent with a monosomic line 3A of a variety Pb. C591 which produce albino seedlings (nullisomics) upon selfing (Singh and Joshi, 1979). All the F1 hybrid plants were analysed cytologically at the first meiotic metaphase. Seeds were taken from all the F1 hybrids separately. Observations made on the F2 seedlings suggested that the variety Mara carries two independent genes which are involved in the biosynthesis of chlorophyll. One of the genes is located on chromosome 3A.


Introduction

It has been demonstrated that the flag leaves of wild species of wheat have higher photosynthetic capacity (Pmax) than those of the bread wheat varieties when expressed per unit leaf area or per unit mass of chlorophyll (Austin, et al., 1986) which indicates that chlorophyll content might be related to Pmax. It is necessary to identify genes for the higher photosynthetic efficiency in wild diploid wheat species in order to transfer them to bread wheat. In fact this kind of selective transfer in the absence of the knowledge of chlorophyll synthetic genes present in the recipient varieties may be difficult. Logically, along with the identification of the genes for higher photosynthetic capacity it is important to identify and locate chlorophyll synthetic gene(s) in the recipient varieties too. With this objective in mind, an Italian hexaploid dwarf wheat Mara was used to identify and locate the gene(s) for chlorophyll synthesis.


Materials and methods

To determine the chromosome(s) carrying genes involved in the biosynthesis of chlorophyll in the variety Mara, it was crossed as a male parent with a monosomic line 3A of a variety Pb. C591 which was reported to carry a gene for chlorophyll synthesis on chromosome 3A (Singh and Joshi, 1979). Seeds obtained from these crosses were planted in the field. All the F1 hybrid plants were analysed cytologically at the first meiotic metaphase (Table 1). Seeds were taken from all the hybrid plants separately and the presence or absence of chlorophyll was determined by germinating these F2 seeds in the petri dishes. The observations were made on the seedlings on individual hybrid plant population basis (Table 1). Observations were also recorded on the seedlings of all the parents involved in the experiment.

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