电子束辐照对不同成熟度番茄后熟及乙烯生成的影响

Effect of Electron Beam Irradiation on Ripening and Ethylene Production of Tomato Fruits Harvested at Different Mature Stages

为明确电子束辐照对跃变型果蔬采后后熟和保鲜的影响,以不同成熟度番茄为试材,10Me V、10 kW电子直线加速器为射线源,采用不同剂量(0、0.4、1.0 kGy)电子束辐照新鲜采收的番茄果实,测定货架(20±1℃,50%RH,14 d)期间的果皮红色指数、乙烯释放量、ACC合成酶(ACS2)基因和ACC氧化酶(ACO1)基因的表达量及保鲜效果。结果表明,电子束辐照可抑制番茄果实货架期后的变红后熟,剂量越高,抑制程度越大,果皮红色指数越低。电子束辐照对14 d货架期间番茄果实的失重、皱缩、霉变无显著影响。电子束辐照对番茄果实乙烯释放量、ACC合成酶基因和ACC氧化酶基因表达量的影响因番茄果实成熟度不同而异。对成熟度低的绿熟期果实,电子束辐照可抑制其乙烯释放和ACC合成酶基因、ACC氧化酶基因的表达。对成熟度高的红熟期果实,电子束辐照可促进其乙烯释放,但乙烯合成关键酶基因表达量高低因电子束辐照剂量而异,1.0 kGy处理可抑制ACC合成酶基因、ACC氧化酶基因的表达。

The goal was to study the effect of electron beam(e-beam)irradiation on postharvest ripening and storage quality of climacteric fruits.Tomato fruits harvested at green,pink and red stages of ripeness were exposed to 0,0.4,and 1.0 kGy e-beam irradiation by linear accelerator(10 MeV,10 kW),and held as shelf-life storage(20±1℃,50%RH)for 14 days.The red color index of tomato,ethylene production,expression of ACC synthetase(ACS2)gene and ACC oxidase(ACO1)gene,storage quality were measured termly.Our results indicated that:red turning of tomato skin was suppressed by e-beam irradiation in a dose dependent manner.The red color indexes were declined with irradiation dose increase.E-beam irradiation showed no significant effects on weight loss,wrinkling and decay of tomato fruits during shelf-life time of 14 days.The effects of e-beam irradiation on ethylene production,expression of ACS2 gene and ACO1 gene were varied with mature stages of harvested tomato fruits.For tomatoes harvested at green stage,production of ethylene and expression of ACS2 gene and ACO1 gene were inhibited by e-beam irradiation.For tomatoes harvested at red stage,production of ethylene was promoted by e-beam irradiation.But effects of e-beam irradiation on expression of ACS2 gene and ACO1 gene for tomatoes harvested at red stage were varied with irradiation dose,and the tomatoes irradiated by 1.0 kGy e-beam showed lower expression level of ACS2 gene and ACO1 gene.