甘藷無病毒苗之培育及病毒檢定

Abstract

感染毒素病葉部出現黃色斑點病徵之甘藷品種臺農63 號，經38~42℃ 熱處理30~90 天，切取莖頂5 cm 長，扦插於培養土或熱處理28 天以上，切取莖頂5 mm 長，培養於改良式Murashige and Skoog 培養基，均不能去除病毒。熱處理28 天以上，切取莖頂0.3-0.6 mm 培養於含BAP ( 6-benzylaminopurine ) 4-8 ppm 及IAA ( Indole-3 -acetic acid ) l ~2 ppm 之改良式MS 培養基，溫度維持25士1 ℃ ，光度0~150 lux，經30~50 天後移置於不含生長素或含Kinetin 2 ppm 之相同培養基，每日光照16 小時，光度3300 lux 以上，照光時溫度在28~32℃ 之間，未照光時溫度為25士1℃ ，於65~120 天可生長成一完全之小苗。以指示植物I ponoea nil 採用機械傳播及嫁接法檢定，66.7% ( 16/24）呈無病毒反應。經檢定結果之無病毒試管苗，切取長度約0.6~0.8 cm 包括一個節之莖，將葉片切除，扦插於改良式MS 培養基，於10~30 天內可生長成一完全之小苗。 Keeping 50mm long terminal growths in growth chamber at 38°-42°C continuously for 30 to 90 days with a daily light peroid of 16 hours at 3300 lux light intensity failed to eliminate a yellow spotting virus from sweet potato cultivar Tainung 63. Neither was the virus eliminated by culturing shoot tips, 5mm in length, in modified Murashige and Skoog’s medium (MS). However, elimination of the virus was achieved by culturing meristem tips, 0.3 to 0.6mm long, taken from virus-infected Tainung 63 which had previously been exposed to 38°-42°C for 28 days. The meristem cultures were grown initially in modified MS medium containing 4-8 ppm 6-benzylaminopurine (BAP) and 1-2 ppm indoleacetic acid (IAA) and were placed under 25 ±1°C for 30 to 50 days at a light intensity of 150 lux or below. Then they were transferred to modified MS with 2 ppm kinetin. A daily light peroid of 16 hours at 3300 lux light intensity and a dark period of 8 hours were provided. The temperatures during the alternative peroids were 28-32°C and 25±1°C, respectively. The excised meristem tissues developed into plantlets within 65 to 120 days. Of 24 such plants, 16 did not cause virus symptoms on I pomoea nil by mechanical transmission and/or grafting. Single-node cuttings of these virus-free test tube plantlets developed into complete plants within 10 to 30 days after subculturing on modified MS medium.