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HEAT STRESS TOLERANCE STUDIES IN CALLUS CULTURES OF GOSSYPIUM HIRSUTUML. CV. ACALA SJ2.

LAL HUSSAIN AKHTAR, JOHN GORHAM*, MASOOD AKHTAR, MUHAMMAD SAFDAR AND MUHAMMAD ASLAM

Abstract: Heat stress tolerance was studied in cotton (Gossypium hirsutum L.). Callus cultures of two cotton cultivars viz., Coker 312 (cotyledonary-derived) and Acala SJ2 (leaf and petiole-derived) showed significant stimulation in growth at stress temperature of 44 °C for 2 hours after 2 days of pre-incubation at 28 °C followed by 26 days of incubation at 28 °C. Reduction in callus growth at 47 and 50 °C was higher in Acala SJ2 compared to Coker 312. Petiole-derived callus exhibited more heat tolerance than leaf-derived callus. At 50 °C callus tissue turned brown. The relative significance of increases in growth rate at 44 °C and drastic reduction in growth rate at temperatures above 44 °C is discussed in the light of heat induced production of proline, glycinebetaine, heat-shock proteins and killing of some viruses which have been reported to protect plant tissues from damage caused by heat stress.

Regional Agricultural Resarch Institute, Bahawalpur, Pakistan.
Centre of Arid Zone Studies, University of Wales, Bangor, LL57 2UW, UK.