معرفي روشي آسان جهت تعيين سطح پلوييدي با استفاده از شمارش كلروپلاستهاي سلولهاي نگهبان روزنه در جنس شبدر

A simple technique for determination of ploidy level using chloroplast number in stomatal guard cells of Trifolium plants

Trib Trifoleae from Fabacea family consists of four genera: Trifolium Medicago, Melilotus and Trigonela. Trifolium is major crop plant of this tribe. Determination of ploidy level is requierd for studying interspecific relationships, developing interspecies hybrids, genetic studying of transgenic plants and plant breeding programs. All species of this genus have small chromosomes, making die conventional chromosom count in root tip cells a difficult task. Therefore an efficient alternative ploidy determination technique is requierd for this group of plants. The relationship between ploidy level and the number of chloroplasts in stomatal guard cells, was studied in 24 populations of 8 species of Trifolium. Three randomly selected middle leaves of greenhouse grown plants were used for chloroplast counting in twenty pairs of stomatal guard cells per each leaf. Chromosome number were also determined in root tip of studied plants. The ploidy level was highly correlated with the number of chloroplasts in stomatal guard cells. Number of chloroplasts in tetraploid population of T. fragiferum was approximately twice as many diploid species : T. spumosum , T. campestre, T. bullatum, T. tomentosume, T. resupinatum and T. physodes. These results suggested that counting chloroplast number in the leaf stomatal guard cells is an efficient alternative technique for determination of ploidy level in the genus Trifolium.