K. A. Timiriasev Institute of Plant Physiology

Use of tissue culture to test plant resistance to abiotic stresses

--Y. I. Dolgykh, S. N. Larina and Z. B. Shamina

The possibility of testing plant tolerance to abiotic stresses using maize tissue culture was examined.

All plant material was obtained from Dr. V. S. Sherbak, VS (Krasnodar Research Institute of Agriculture). Seeds of four maize inbreds which differed in drought resistance were germinated in NaCl (2%) or PEG (25%) solutions, the number of germinated seeds was counted and the size of shoots and roots was measured. Leaves of 2-week-old seedlings were used to determine the ratio of physiologically bounded and free water. Embryo-produced calli of these lines were grown on Murashige-Skoog medium supplemented with 0.5-2.5% NaCl or 5-30% PEG.

Callus growth on PEG-containing media and energy of seed germination under osmotic stress were found to be similar for each of the genotypes (Fig. 1). Distribution of inbreds according to their water-bounding capacity and callus sensitivity was the same with the exception of line Gn118. This line is likely to have other mechanisms of drought resistance.

 Tested inbreds did not show significant difference in callus growth and energy of seed germination under NaCl stress (Fig. 2).

The sensitivity of seeds and callus culture to NaCl could not be related to their sensitivity to PEG--the genotypes most tolerant to NaCl could be the most sensitive to PEG. Salt tolerance of tested inbreds is apparently determined by resistance to toxic effect of ions, but not to osmotic stress.

The fact that stress sensitivity of callus was positively correlated with stress sensitivity of intact plants allows employment of tissue culture for screening salt and drought resistant variants.

Several tolerant cell lines were selected from 8 inbreds and hybrids of maize on media supplemented with 1.5% NaCl or 25% PEG. Callus viability on NaCl medium was 20-30% and did not depend on genotype. Callus viability on PEG medium fluctuated from 7 to 76% for different genotypes. 167 PEG-tolerant plants, 69 NaCl-tolerant plants and 11 plants tolerant to both factors were regenerated from selected calli. Field resistance of these plants will be tested in 1992.

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